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BOOK OF
ABSTRACTS
7th
International Congress
on the Application of
Raman Spectroscopy
in Art and Archaeology
2-6 September 2013
7 th International Congress on the
Application of Raman Spectroscopy
Book of Abstracts
7th International Congress on the
Application of Raman Spectroscopy
Ljubljana, Slovenia, 2th–6th September 2013
Book of Abstracts
7th International Congress on the Application of Raman Spectroscopy in Art and Archaeology (RAA 2013),
Ljubljana (Slovenia), 2th–6th September 2013
Publisher: Institute for the Protection of Cultural Heritage of Slovenia
Editors: Polonca Ropret, Nadja Ocepek
Editorial Board: Klara Retko, Lea Legan, Tanja Špec, Črtomir Tavzes
Print: Birografika BORI d.o.o.
Copies: 400
Copyright © RAA 2013 and the Authors
All Rights Reserved
Ljubljana 2013
No part of the material protected by this copyright may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any storage or retrieval system, without written permission from the copyright owners.
The publication is published with the financial support of the Ministry of Culture, and is not payable.

REPUBLIC OF S LOVENIA
MINISTRY OF CULTURE
CIP - Kataložni zapis o publikaciji
Narodna in univerzitetna knjižnica, Ljubljana
543.424.3:7(082)
543.424.3:902(082)
INTERNATIONAL Congress on the Application of Raman Spectroscopy in Art and Archaeology (7 ; 2013 ; Ljubljana)
Book of abstracts / 7th International Congress on the Application of Raman Spectroscopy
in Art and Archaeology, Ljubljana (Slovenia), 2th-6th September 2013 ; [editors Polonca Ropret, Nadja Ocepek]. - Ljubljana : Institute for the
Protection of Cultural Heritage of Slovenia, 2013
ISBN 978-961-6902-38-0
1. Ropret, Polonca, kemik
268489728
RAA 2013
6
The use of Raman spectroscopy for identifying and studying the material component of the objects of art and
antiquities has flourished in recent years. The increasing importance of the application of Raman spectroscopy
in art and archaeology is illustrated by an increasing number of research papers published each year, and by the
scientific conferences and sessions that have been dedicated to this research area in the past decade.
The RAA conferences promote Raman spectroscopy and play an important role in the increasing field of its application in Art and Archaeology. The RAA is an established biennial international event. It brings together
studies from diverse areas and represents dedicated work on the use of this technique in connection to the fields
of art-history, history, archaeology, palaeontology, conservation and restoration, museology, etc. Furthermore,
the development of new instrumentation, especially for non-invasive measurements, has received a great attention in the past years. These prominent, international events have a long tradition. Previously they were held in
London (2001), Ghent (2003), Paris (2005), Modena (2007), Bilbao (2009), Parma (2011), and this year (2013)
in Ljubljana.
The RAA 2013 conference received over 100 high quality contributions from different research laboratories all
over the world, and this book of abstracts presents their latest advancements. One of the important topics is
studies of deterioration induced by different environmental factors, such as biodeterioration, pollution, light and
humidity exposure. The outcomes of these studies can give important information for designing safe conservation – restoration treatments and help in creating a better environment for cultural heritage objects, for their
storage and display, all contributing to increasing of its sustainability. A great number of research contributions
are presenting the latest achievements in the characterisation of traditional organic colorants by introducing
new solutions for Surface enhanced Raman spectroscopic studies. This is an important topic that contributes to
understanding not only the composition of the organic colorants, but also their production processes. The advancements in metals characterisation give important information to understanding of their corrosion processes
and/or deliberate patinations by artists, which can give important input in designing further corrosion inhibition
processes. A special topic is dedicated to the archaeometry research, from characterisation of ancient artefacts,
their degradation processes, to finding possible solutions for their preservation. New, presented knowledge on
gemstones characterisation, provenance, authenticity research, and furthermore, forensics applications, all attest
of the wide applicability of Raman spectroscopy. The latest innovations in Raman instrumentation is presented
by well – known companies in the field of Raman instruments, with a special emphasis in the development of
portable, non-invasive instruments. Many research laboratories are taking the advantage of non-invasive instruments in order to keep the full integrity of works of art. However, the interpretation of the results is often challenging, which gives scientific contributions dealing with these questions a special, important place. Finally, the
importance of a comprehensive Raman database is emphasised, and the latest work of the Infrared and Raman
Users Group (IRUG) is presented, a database which we all help creating, and which can help in solving many
questions that we all face.
We wish to thank all of the authors who submitted their latest research results and helped creating the scientific
program of the RAA 2013 conference, as well as this Book of Abstracts.
On behalf of the organizing committee,
Polonca Ropret,
Research Institute, Conservation Centre,
Institute for the Protection of Cultural Heritage of Slovenia
7
Book of Abstracts
Scientific Committee
Dr. Polonca Ropret
Research institute, Conservation Centre,
Dr. Danilo Bersani
Dipartimento di Fisica e Scienze della Terra,
Università degli Studi di Parma, Italy
Prof. Dr. Juan Manuel Madariaga
Department of Analytical Chemistry, Faculty of Science and Technology,
University of the Basque Country, Spain
Prof. Dr. Peter Vandenabeele
Research group in Archaeometry, Department of Archaeology,
Ghent University, Belgium
Prof. Dr. Howell G. M. Edwards
Centre for Astrobiology and Extremophiles Research,
School of Life Sciences, University of Bradford, UK
Prof. Dr. Pietro Baraldi
Department of Chemical and Geological Sciences,
University of Modena and Reggio Emilia, Italy
Dr. Sandrine Pagès-Camagna
Centre de Recherche et de Restauration des Musées de France (C2RMF), France
Dr. Francesca Casadio
The Art Institute of Chicago, USA
RAA 2013
8
Organizing Committee
Janez Kromar
Director of Conservation Centre,
Jernej Hudolin
Head of Restoration Centre,
Conservation Centre,
Dr. Polonca Ropret
Head of Research Institute
Conservation Centre,
Dr. Črtomir Tavzes
Tanja Špec
Lea Legan
Klara Retko
Nadja Ocepek
9
Book of Abstracts
List of accepted works with corresponding authors
PL: Plenary Lecture
OP: Oral Presentation
P: Poster Presentation
Monday, September 2, 2013
ORAL SESSION 1
Deterioration studies and organic materials
Raman Spectroscopy of Extremophilic
Biodeterioration: An Interface between Archaeology
and the Preservation of Cultural Heritage
Howell G. M. Edwards
PL120
Identification of endolithic survival strategies on stone
monuments
Annalaura Casanova Municchia
OP122
FT-Raman analysis of historical cellulosic fibres
infected by fungi
Katja Kavkler
OP224
Combined FT-Raman and Fibre-Optic Reflectance
Spectroscopic Characterisation of Simulated Medieval
Paint Films: a Chemometric Study of the Effects of
Natural and UV-Accelerated Ageing
Anuradha Pallipurath
OP326
Study of malachite degradation in easel (model)
paintings by spectroscopic analysis
Tanja Špec
OP427
Portable and laboratory analysis to diagnose the
formation of efflorescence on walls and wall paintings
of Insula IX, 3 (Pompeii, Italy)
Juan Manuel Madariaga
OP529
Decorated plasterwork in the Alhambra investigated by
Raman spectroscopy: field and laboratory comparative
study
Ayora-Cañada María José
OP631
Multi-technical approach for the study of French
Decorative Arts furniture and luxury objects
Céline Daher
OP733
Deterioration of lead based pigments on a fresco: a
micro-Raman investigation
Ilaria Costantini
P135
Investigation of colour layers in easel (model) paintings
influenced by different ageing processes
Klara Retko
P236
POSTER SESSION 1
RAA 2013
10
Identification of copper azelate in 19th century
Portuguese oil paintings: Characterisation of metal
soaps by Raman Spectroscopy
Vanessa Otero
P338
Raman study of pigment degradation due to acetic acid
vapours
Alessia Coccato
P440
Investigating the sources of degradation in corroded
lead sculptures from Oratory Museum (Museu do
Oratório), Brazil
Thiago Sevilhano Puglieri
P542
Evora Cathedral: Pink! Why not?
Ana Teresa Caldeira
P644
Study of red biopatina composition on sandstone
from a historical war Fort in La Galea (Biscay,
north of Spain) by means of single point focusing
Raman analysis and Raman Imaging combined with
microscopic observation
P746
Raman and non invasive IR analyses of natural
organic coatings: application to historical violin
varnishes
Céline Daher
P848
Characterization of green copper organometallic
pigments and understanding of their degradation
process in European easel paintings
Carlotta Santoro
P950
Optical Microscopy and Micro-Raman studies of The
Hans Memling’s Triptych “The Last Judgment”
Ewa Pięta
P1051
Non-destructive micro-Raman and XRF investigation
on parade saddles of italian renaissance
Pietro Baraldi
P1152
Cecilia Baraldi
P1254
Raman microscopy and X-ray fluorescence for the
rediscovering of polychromy and gilding on classical
statuary in the Galleria degli Uffizi
Pietro Baraldi
P1356
Raman spectroscopic investigation of black pigments
Alessia Coccato
P1458
Kepa Castro
P1560
Mohsen Ghanooni
P1662
Phoenicians preferred red pigments: micro-Raman
investigation on some cosmetics found in Sicily
archaeological sites
Raman Spectroscopy and SEM-EDS Studies Revealing
Treatment History and Pigments of the Government
Palace Tower Clock in Helsinki Empire Senate Square
Feasibility Study of Portable Raman Spectroscopy for
Characterization of Ground Material of Easel Paintings
(Case Study: Sradar As’ad-e Bakhtiary Painting of
Kamal-al Molk)
11
Book of Abstracts
The Sibyls from the church of San Pedro Telmo: a
spectroscopic investigation
Marta S. Maier
P1764
Debbie Lauwers
P1866
Petra Bešlagić
P1968
RENISHAW: New Methods in Raman Spectroscopy –
Combining Other Microscopes for mineral and pigment
analysis
Josef Sedlmeier
OP870
HORIBA JOBIN YVON: Advances in Raman
instrumentation: explore new boundaries in Art and
Archaeology
Romain Bruder
OP972
NORDTEST: A portable 1064 nm Raman spectrometer
for analysis of cultural heritage items
Alessandro Crivelli
OP1073
BAYSPEC: Novel 1064 nm Dispersive Raman
Spectrometer and Raman Microscope for Non-invasive
Pigment Analysis
Lin Chandler
OP1175
Surface-Enhanced Raman Spectroscopy in Art and
Archaeology
Marco Leona
PL278
TLC-SERS of mauve, the first synthetic dye
Maria Vega Cañamares
OP1280
New photoreduced substrate for SERS analysis of
organic colorants
Klara Retko
OP1382
Laser Ablation Surface-enhanced Raman
Microspectroscopy
Pablo S. Londero
OP1484
Pigment identification of illuminated medieval
manuscripts by means of a new, portable Raman
equipment
Micro-Raman identification of pigmentson wall
paintings: characterisation of Langus and Sternen’s
palettes
ORAL SESSION 2
Tuesday, September 3, 2013
ORAL SESSION 3
Surface Enhanced Raman Spectroscopy in Art
and Archaeology
RAA 2013
12
Silver colloidal pastes for the analysis via Surface
Enhanced Raman Scattering of colored historical
textile fibers: some morphological and spectroscopic
considerations
Ambra Idone
OP1586
Surface enhanced Raman spectroscopy for dyes and
pigments – Can non-invasive investigations become a
reality?
Brenda Doherty
OP1688
Surface Enhanced Raman Scattering of organic dyes on
gold substrates prepared by pulsed laser ablation
N. R. Agarwal
OP1790
Combining SERS with chemometrics: a promising
technique to assess historical samples with historically
accurate reconstructions
Rita Castro
OP1892
Characterization and Identification of Asphalts in
Works of Art by SERS complemented by GC-MS, FTIR
and XRF
María Lorena Roldan
OP1994
Study of Raman scattering and luminescence
properties of orchil dye for its nondestructive
identification on artworks
Francesca Rosi
OP2095
Application to historical samples of in situ,
extractionless SERS for dye analysis
Ambra Idone
P2096
Application of surface-enhanced Raman spectroscopy
(SERS) to the analysis of red lakes in French
Impressionist and Post-Impressionist paintings
Federica Pozzi
P2198
Surface-Enhanced Raman Spectroscopy (SERS)
of historical dyes on textile fibers: evaluation of an
extractionless treatment of samples
Chiara Zaffino
P22100
Suitability of Ag-agar gel for the micro-extraction of
organic dyes on different substrates: the case study of
wool, silk, printed cotton and panel painting mock-ups
Elena Platania
P23102
PB15 polymorphic distinction in paint samples
by combining micro-Raman spectroscopy and
chemometrical analysis
Jolien van Pevenage
P24104
POSTER SESSION 2
13
Book of Abstracts
First identification of the painting technique in 18th
Century Transylvanian oil paintings using microRaman and SERS
Oana-Mara Gui
P25106
Organic materials in oil paintings and canvas revealed
by SERS
Oana-Mara Gui
P26108
Characterization of SOPs in acrylic and alkyd paints by
means of µ-Raman spectroscopy
Marta Angehelone
P27110
Synthetic Polymers and Cultural Heritage. Analytical
approach by Raman spectroscopy
Margarita San Andrés
P28112
Raman monitoring of the sol-gel process on OTES/
TEOS hybrid sols for the protection of historical glasses
L. de Ferri
P29114
Possible differentiation with Raman spectroscopy
between synthetic and natural ultramarine blues.
Comparative analysis with the blue pigment of a
painting of R. Casas (1866–1932)
A. R. De Torres
P30116
Raman monitoring of the polymerization reaction of a
hybrid protective for wood and paper
Laura Bergamonti
P31118
Reference Raman data of the artist palette – tool for insitu investigation of J. Matejko (1838–1893) paintings
Iwona Żmuda-Trzebiatowska
P32119
Material analysis of the Manueline Foral Charters of
Lousã and Marvão
António Candeias
P33121
Materials and gilding techniques on plasterwork in the
Alhambra (Granada, Spain)
Domínguez Vidal Ana
P34123
Characterization of gypsum and anhydrite ground
layers on 15th and 16th centuries Portuguese painting
by Raman Spectroscopy, Micro X-ray diffraction and
SEM-EDS
António Candeias
P35125
Identification of deteriorated pigments on wall
paintings from Lutrovska klet, Sevnica, Slovenia,
using Raman spectroscopy and SEM-EDS
Katja Kavkler
P36128
Characterization of middle age mural paintings: in
situ Raman spectroscopy associated with different
techniques
Julene Aramendia
P37130
RAA 2013
14
Raman microspectroscopic identification of pigments
of newly discovered gothic wall paintings from the
Dominican Monastery in Ptuj (Slovenia)
Maja Gutman
P38132
Shot Noise Reduction through Principal Components
Analysis
J. J. González-Vidal
P39134
Raman investigation of artificial patinas on recent
bronze, protected by different azole type inhibitors in
outdoor environment
Tadeja Kosec
OP21135
Micro-Raman Investigation on corrosion of Pb-Based
Alloy Replicas
Giorgia Ghiara
OP22136
Conservation diagnosis of weathering steel sculptures
using a new Raman quantification imaging approach
Julene Aramendia
OP23138
Raman study of the salts attack in archaeological
metallic objects of the Middle Age: The case of
Ereñozar castle (Bizkaia, Spain)
Kepa Castro
OP24140
The Contribution of Archaeometry to Understanding
of the Past Effects and Future Changes in the World
Heritage Site of Pompeii (Italy)
PL3143
Raman spectroscopy applied to the study of Cretaceous
fossils from Araripe Basin, Northeast of Brazil
Paulo T. C. Freire
OP25145
Raman spectroscopic analyses of~75. 000 year old
stone tools from Middle Stone Age deposits in Sibudu
Cave, KZN, South Africa
Linda C. Prinsloo
OP26147
Raman Spectroscopy in Archaeometry: multi-method
approaches and in situ investigations: advantages and
drawbacks
Peter Vandenabeele
OP27149
ORAL SESSION 4
Raman for characterization of metal artefacts
Thursday, September 5, 2013
ORAL SESSION 5
Raman Spectroscopy in Archaeometry
15
Book of Abstracts
Spectroscopic Analysis of Chinese Porcelain Excavated
in Clairefontaine (Belgium): Pigment Identification and
Dating
Jolien van Pevenage
OP28150
Characterization of ancient ceramic using microRaman spectroscopy: the cases of Motya (Italy) and
Khirbetal-Batrawy (Jordan)
Laura Medeghini
OP29152
Hispano-Moresque architectural tiles from the
Monastery of Santa Clara-a-Velha, in Coimbra,
Portugal: a µ-Raman study
Vânia S. F. Muralha
OP30154
The blue colour of glass and glazes in Swabian contexts
(South of Italy): an open question
Maria Cristina Caggiani
OP31155
Spectroscopic characterisation of crusts interstratified
with prehistoric paintings preserved in open-air rock
art shelters
Antonio Hernanz
OP32157
Micro-Raman on Roman glass mosaic tesserae
Claudia Invernizzi
P40159
Raman and IR Spectroscopic Study of Vitreous
Artefacts from the Mycenaean to Roman Period: Glassy
Matrix & Crystalline Pigments
Doris Möncke
P41160
The detection of Copper Resinate pigment in works of
art: contribution from Raman spectroscopy
Irene Aliatis
P42162
Micro-Raman and internal micro-stratigraphic
analysis of the paintings materials in the rockhewn church of the Forty Martyrs in Şahinefendi,
Cappadocia (Turkey)
Clauda Pelosi
P43164
Vibrational characterization of the new gemstone
Pezzottaite
Erica Lambruschi
P44166
FTIR-ATR and ESEM of wall paintings from the tomb
of Amenemonet (TT277), Qurnet Murai necropolis,
Luxor, Egypt
Mohamed Abd El Hady
P45168
Physico-chemical characteristics of Predynastic pottery
objects from Maadi – Egypt
Mohamed Abd El Hady
P46170
POSTER SESSION 4
RAA 2013
16
Raman Database of Corrosion Products as a powerful
tool in art and archaeology
Serena Campodonico
P47171
MicroRaman as a powerful non-destructive technique
to characterize ethonological objects from D’Albertis
Castle Museum of World Cultures in Genova
Serena Campodonico
P48173
Micro ATR-IR study of pollutions affecting radiocarbon
dating of ancient Egyptian mummies
Ludovic Bellot-Gurlet
P49175
Raman Scanning of Biblical Period Ostraca
Arie Shaus
P50176
Analyses of pigments from 4th century B.C. the
Shushmanets tombs in Bulgaria
Cristina Aibéo
P51178
Raman Spectroscopic Study of the Formation of Fossil
Resins Analogs
Margarita San Andrés
P52179
Pigments from Templo Pintado (Pachacamac, Perú)
investigated by Raman Microscopy
Dalva Lúcia Araújo de Faria
P53181
Lithic tools raw materials recognition by Raman
spectroscopy of Palaeolitihic artifacts
Sonia Murcia-Mascaros
P54183
Raman characterization on historical mortar. Crossing
data with XRD and Color Measurements
Dorotea Fontana
P55184
Roman ceramics from Vicofertile (Parma, Italy):
micro-Raman study of the heat diffusion during the
production process
Elisa Adorni
P56185
Raman spectroscopic study on ancient glass
beads found in Thailand archaeological sites
Pisutti Dararutana
P57187
Identification of Neolithic jade found in Switzerland
studied using Raman spectroscopy: Jadeite – vs.
Omphacite – jade
Marie Wörle
P58188
Raman Spectroscopy as useful tools for the
gemmological certification and provenance
determination of sapphires
Simona Raneri
P59190
Authentication of ivory by means of 1064 nm Raman
spectroscopy and X-ray fluorescence spectrometry
Alessandro Crivelli
P60191
17
Book of Abstracts
ORAL SESSION 6
Characterization of Gems and Forensic
Applications
Characterization of emeralds by micro-Raman
spectroscopy
Raman micro spectroscopy of inclusions in gemstones
from a chalice made in 1732
Danilo Bersani
OP33192
Miha Jeršek
OP34194
Spectroscopic investigation: impurities in azurite as
provenance markers
Lucia Burgio
OP35196
Implementation of scientific methods of fine art
authentication into forensics procedures: the case study
of “Bolko II Świdnicki” by J.J Knechtel
Barbara Łydżba-Kopczyńska
OP36198
Raman analysis of multilayer automotive paints in
forensic science: measurement variability and depth
profile
Danny Lambert
OP37200
The Art of non-invasive in situ Raman spectroscopy:
identification of chromate pigments on Van Gogh
paintings
Costanza Miliani
PL4203
Characterisation of a new mobile Raman spectrometer
for in-situ analysis
Debbie Lauwers
OP38205
Martin A. Ziemann
OP39207
Odile Madden
OP40208
Marcello Picollo
PL5210
Friday, September 6, 2013
ORAL SESSION 7
Non-invasive Raman Investigation
On-site high-resolution Raman spectroscopy on
minerals and pigments
Molecular characterization and technical study of
historic aircraft windows and head gear using portable
Raman spectroscopy
ROUND TABLE – Raman
spectral database
The Infrared and Raman Users Group Web-based
Raman Spectral Database
RAA 2013
18
Monday, September 2
PL1
Raman Spectroscopy of Extremophilic Biodeterioration: An
Interface Between Archaeology and the Preservation of Cultural
Heritage
Howell Gwynne M. Edwards1*
1
Centre for Astrobiology and Extremophiles Research, School of Life Sciences,
University of Bradford, West Yorkshire, UK, + 44 1274 233787, [email protected]
The identification of biological colonisation in archaeological artefacts and ancient art works represents
major problems for the preservation of materials and objects of cultural heritage for conservation
scientists and art restorers with the realisation that the deleterious effects of this colonisation can
be ongoing even when the artworks have been prepared for storage. The conservation strategies and
curation of biodegraded objects from archaeological sites are especially difficult to enforce when the
incipient damage has yet to be made evident. Artefacts composed of biological materials are particularly
susceptible to biological degradation especially by extremophilic organisms which have developed
sophisticated chemical protection strategies for survival in extreme environments which prove to
be toxic to other organisms. The application of analytical Raman spectroscopic techniques to the
characterisation of the chemical composition of mineral and synthetic paint pigments, ceramics, resins,
dyes, textiles and human skeletal remains is also now finding much interest in cultural heritage circles;
during these studies it has become apparent that the spectral signatures of biological colonisations that
are responsible for the serious deterioration or degradation of archaeological artefacts are closely similar
to those which one might expect to find with remote robotic Raman spectroscopic instrumentation on
planetary surface and subsurface exploration rover vehicles for the detection of extinct or extant life.
The miniaturisation of Raman spectrometers for the detection of life signatures on planets and their
satellites in our Solar System is exemplified by the forthcoming ESA ExoMars mission to the planet
Mars which will specifically search for extant or extinct life in the Martian subsurface geological record
through a powerful suite of instrumentation that includes a Raman laser spectrometer for the first time.
A database of key Raman spectral signatures of species such as carotenoids, chlorophyll, scytonemin
and other key protective biochemicals produced by terrestrial specimens of cyanobacterial and lichen
extremophiles which exist in stressed hot and cold terrestrial environments such as the Atacama Desert,
Arctic meteorite impact craters, volcanic outcrops in Svalbard and the dry Valleys in Antarctica is being
complied to identify the presence of biological colonisation in suitable rock matrices. The adaptation
of the mineralogy and the host geological matrices by the cyanobacterial colonies and their production
of protective biochemicals is a vital requirement for the survival strategy for biological growth and
evolution. This is also the case for the biological colonisation of archaeological relics excavated from
a depositional environment and a readily available spectral database can hence be assimilated for
the identification and characterisation of areas of biological degradation in ancient artefacts which
may be used to alert conservators to the urgent need for restorative and preservative strategies to
prevent further ongoing specimen deterioration subsequent to superficial cleaning procedures being
undertaken.
The potential afforded by the reduction in size and increased portability of Raman spectrometers
appeals to conservation scientists for the in situ analytical measurements that can be performed on
RAA 2013
20
PL1
objects without the need for destructive sampling, often in inaccessible locations, and an awareness
that the Raman spectral information can reveal the presence of biological agents that could cause
the ongoing deterioration of a cultural object need to be recognised. Also, the unsightly growths of
cyanobacteria and lichen communities on exposed works of art such as wall paintings, statues and
frescoes can be very deleterious and damaging to artistic viewing; in this context, the ability of biological
colonies to attach themselves to mineral pigments which are often very hazardous and highly toxic to
humans, such as compounds of lead, copper, mercury, antimony and arsenic provides an example of
extremophilic behaviour which equally matches the strategies they have adopted to overcome extremes
of temperature, pH, radiation insolation and barometric pressure elsewhere terrestrially.
Hence, in this presentation we shall explore some examples of the occurrence of biological colonisation
of art works and artefacts in which Raman spectroscopy has provided novel information about the
onset of degenerative processes which are often apparent spectroscopically before they are observed
visually; this affords the establishment of analytical Raman spectroscopy as an early warning monitor
of biological degradation in an artefact which may therefore require urgent conservational treatment
to prevent further damage occurring and which will lend support to the apparently unrelated scientific
engagement between Raman spectroscopists working on space missions and in the field of cultural
heritage preservation.
- The examples used to illustrate this approach will be taken from the following cultural heritage
case-studies and scenarios;
- Lichen degradation of wall-paintings;
- Biological colonisation of badly damaged frescoes undergoing restoration;
- Degradation of human mummies from Egyptian Dynastic burials preserved in museum collections;
- Biological invasion of grave sites and contributions to the mineral degradation of human skeletal
remains;
- Definition of biological spectral signatures in archaeological excavations of human and mammoth
remains;
The impact of space mission derived data for key biological signatures on the identification of similar
signatures from biodegraded artefacts from archaeological excavations will inform future Raman
spectrosopic applications for such instruments in archaeological and cultural heritage site work and
the identification of biological and associated mineralogical materials which could advise and inform
future conservation protocols and approaches.
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Book of Abstracts
OP1
Identification of endolithic survival strategies on stone monuments
Annalaura Casanova Municchia,1* Giulia Caneva,1 Maria Antonietta Ricci,1
Armida Sodo1
1
Department of Sciences, University of Roma Tre, Rome, Italy, +39 06 5757336374,
[email protected]
A relevant aspect of stone bio-deterioration is the colonization by endolithic microorganisms that
penetrate some millimetres or even centimetres into the rock. This phenomenon is mainly due to a
strategy of protection from desiccation and high solar radiation.[1–3]
In the literature there are only few studies about the impact of endolithic microorganisms on stone
monuments, and on the ecological conditions favouring this kind of colonization. Additionally most
studies refer to colonization at extreme environmental conditions, such as cold and hot deserts.
Nevertheless, the presence of endolithic microorganisms has been observed in stone monuments
in Temperate and Mediterranean climates, especially in comparably dry environments (e.g. vertical
surfaces of buildings exposed to sunlight).[4–6]
In recent years the study of endolithic organisms in extreme environments has been busted by several
astrobiological studies, aimed at finding a trace of life on Mars, where cold deserts, such as Antarctica
or the Arctic, have been proposed as the closest analogues to Martian on Earth.[7–9] Consequently,
the interest for the development of techniques and protocols for the identification of endolithic
microorganisms on stones is spread over a wide scientific field.
We have used Raman spectroscopy to identify rock alteration and pigments traces produced by endolithic
microorganisms as survival and adaption strategies to adverse conditions on stones monuments.
Notably this technique can easily be implemented (and already is) in space missions.
Endolithic cyanobacteria can produce photo protective accessory pigments, such as scytonemin,
parietin, calycin; they also mobilize some iron oxides to create a mineral screen layer on the rock
surface. In both cases they leave biological or geological traces on rock due to their metabolic activity
or indirect effects.
We have performed the experiment on different rock samples, in order to investigate the impact
of endolithic microorganisms on stone monuments from areas characterized by Temperate and
Mediterranean climates. In detail, the aim is to detect key biomarkers and geomarker providing an
indicator of different adaptation strategies used in adverse condition and identifying the alterations
produced on the substrate.
Figure 1. Microphotographs of cross-section. a.) Sample of Church of Martvili b.) Sample of
Hebrew’s cemetery tombstone c.) Sample of cliff of the Amalfi Coast.
RAA 2013
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Three different case studies were investigated: Marly limestone samples from the outer wall of Church
of the Virgin in Martvili in Georgia that showed a peculiar bio deterioration form, Istrian stone samples
from Hebrew’s cemetery tombstone in Venice, and carbonate samples from calcareous cliff of the
Amalfi Coast.
In this work we report the observations of cross-section by optical microscope (Figure 1) and scanning
electron microscope (SEM) in order to identify the interaction between substrate and microorganisms.
Spectra obtained by Raman spectroscopic investigations, carried out in cross-section, were useful to
determine the organic and inorganic compounds used by microorganisms as protective mechanisms
against stress conditions.
The data obtained from the spectra gave rise to identification of molecular bio and geo-marker.
References
[1] C. K. Gehrmann, W. E. Krumbein, K. Peterson, International Journal of Mycololgy and Lichenology.
1992, 5, 37–48.
[2] O. Salvadori, Characterisation of endolithic communities of stone monuments and natural outcrops.
In: O. Ciferri, P. Tiano, G. Mastromei, Of Microbes and Art. The Role of Microbial Communities in the
Degradation and Protection of Cultural Heritage. 2000, pp. 89–101.
[3] G. Caneva, M. P. Nugari, O. Salvadori, Plant Biology for Cultural Heritage. Biodeterioration and
Conservation. The Getty Conservation Institute, Los Angeles, 2009.
[4] A. Danin, G. Caneva, International Biodeterioration & Biodegradation. 1990, 26, 397–417.
[5] V. Lombardozzi, T. Castrignanò, M. D’Antonio, A. Casanova Municchia, G. Caneva, International
Biodeterioration & Biodegradation. 2012, 73, 8–15.
[6] C. Ascaso, J. Wierzchos, J. Delgado Rodrigues, L. Aires-Barros, F. M. A. Henriques, A. E. Charola,
International Zeirschrift fur Bauinstandsetzen. 1998, 4, 627–640.
[7] H. G. M. Edwards, E. M. Newton, D. L. Dickensheets, D. D. Wynn-Williams, Spectrochimica Acta Part A.
2003, 59, 2277–2290.
[8] S. E. J. Villar, H. G. M. Edwards, C. S. Cockell, Analyst. 2005, 130, 156–162.
[9] S. E. J. Villar, H. G. M. Edwards, Raman spectroscopy in astrobiology. Anal Bioanal Chem. 2006, 384(1),
100–113.
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FT-Raman analysis of historical cellulosic fibres infected by fungi
Katja Kavkler,1* Andrej Demšar2
Restoration Centre, Conservation Centre, Institute for the Protection of Cultural Heritage of Slovenia,
Ljubljana, Slovenia, [email protected]
2
Department of Textiles, University of Ljubljana, Faculty of Natural Sciences and Engineering,
Ljubljana, Slovenia, [email protected]
1
Introduction
Historical textiles can be degraded by different internal and external factors. Fungi are one of the most
severe textiles’ degraders [1], which attack especially pre-degraded materials, since the depolymerisation
and changes in inter- as well as intramolecular bonds facilitate access of fungal enzymes to molecules.
Textile deterioration has been studied previously with different methods [2,3]. This time we decided to
analyse bio-deteriorated as well as non-affected objects by FT-Raman spectroscopy.
Materials and methods
Textile samples
Historical samples were obtained from 14 different historical textile objects originating from different
historical periods since 16th century. The samples were taken off in the form of pieces of fabrics or
single threads, from objects, where stains were observed, for which we suspected to be of fungal origin,
or where mycelium was observed on the surface of the objects.
FT-Raman
The FT-Raman instrument is a Bruker multiRAM with cryo‑cooled Ge detector and a Nd‑YAG laser
with a wavelength of 1064 nm with a line width of ~ 5‑10 cm‑1 and a resolution of 4 cm‑1. The software
used is OPUS Beta version. The laser intensity has been between 30 and 150 mW. The number of scans
has generally been between 100 and 5000. The surface area of analysis is ~ 20 µm in diameter.
Results and discussion
Of all the 14 investigated objects, three were made of cotton, two of mixture of flax and hemp and all
others of pure flax. Half of the investigated objects were infected by different fungal strains, among
them one made of cotton and six made of flax. The infected cotton object was underwear, whereas all
other infected objects were painting canvases.
We observed structural properties using FT-Raman spectroscopy, after the dispersive Raman
spectroscopy proved to be long lasting and not always reliable method [2]. However, the FT-Raman
spectroscopic method caused some problems with luminescent background as well. The spectra of
non-infected cotton specimen, spectra of both samples with mixed fibres as well as two spectra of flax
had strong background with non-visible or barely visible cellulose bands and their structure could not
be interpreted.
To determine structural changes within cellulose fibres we compared spectra from investigated objects
with those from contemporary fibres, processed in old fashioned manner, of natural colour and nonsized. Some differences in spectra can be attributed to different growth and processing conditions, but
others are sings for different intensive structural changes.
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OP2
The inoculated object made of cotton gave spectra with only low background and clear bands. From
the spectrum we concluded, that ageing as well as biodeterioration caused decreased crystallinity of
cellulose and its degradation [4], as seen from the decrease of the bands at 380 cm-1, 437 cm-1, 1096 cm-1
and 1120 cm-1.
Of the investigated objects made of flax, six were inoculated and four not. In one of the non-inoculated
spectra, obtained from the only object made of flax, which was not painting but an embroidered
tablecloth, we could observe opposite changes than usually. The increased bands at 457 cm-1, 520 cm-1
and 1120 cm-1 are signs of increased crystallinity or more ordered cellulose structure [4-6].
In spectra of two of the inoculated samples no bands could be observed due to strong background
emissions, which is probably the consequence of bio-deterioration [5]. In one spectrum only the strongest
bands were visible. Due to deterioration the two bands around 1100 cm-1 joined into a broad band with
peak at 1096 cm-1. In three inoculated specimens bands were clearly visible despite the luminescent
background, and the structural changes could be investigated. The decreased bands at 995 cm-1 and
1480 cm-1 are a sign of deterioration of cellulose in all three investigated spectra, [7] as well as the
decrease of the bands at 1096 cm-1 and 1120 cm-1 [5] in two spectra.
From the results of the FT-Raman analysis of museum objects infected by fungi we can conclude that as
does the dispersive Raman, also the FT-Raman can cause difficulties when analysing historical textiles,
especially when the fibres are severely deteriorated. However, structural changes can be observed in
most of the spectra already after a short acquisition times. In the investigated specimens we observed
that not only biodeterioration, but also other ageing factors can cause changes in cellulose structure.
As seen from our results, the fungi caused more severe decrease in crystallinity than environmental
factors.
The authors would like to thank Ingalill Nystrom and Department for Conservation of the University
of Gothenburg, Sweden, for giving the possibility to use the FT-Raman in their institution. We would
also like to thank Slovene Museum of Christianity, Ptuj Regional Museum and Department for Easel
Paintings of the Restoration Centre of the Institute for the Protection of Cultural Heritage of Slovenia
for providing the sampling objects.
References
[1] A. Seves, M. Romanò, T. Maifreni, S. Sora, O. Ciferri, International Biodeterioration & Biodegradation.
1998, 42, 203.
[2] K. Kavkler, A. Demšar, Spectrochimica Acta. Part A. 2011, 78(2), 740–746.
[3] K. Kavkler, N. Gunde-Cimerman, P. Zalar, A. Demšar, Polymer degradation and stability. 2011, 96(4), 574.
[4] M. Petrou, H. G. M. Edwards, R. C. Janaway, G. B. Thompson, A. S. Wilson, Analytical and Bioanalytical
Chemistry. 2009, 395, 2131.
[5] H. G. M. Edwards, J. M. Chalmers, Raman Spectroscopy in Archaeology and Art History, Royal Society of
Chemistry: Cambridge, Great Britain, 2006, p. 304.
[6] H. G. M. Edwards, N. F. Nikhassan, D. W. Farwell, P. Garside, P. Wyeth, J. of Raman spectrosc. 2006, 37,
1193.
[7] H. G. M. Edwards, E. Ellis, D. W. Farwell, R. C. Janaway, J. of Raman Spectrosc. 1996, 27, 663.
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Combined FT-Raman and Fibre-Optic Reflectance Spectroscopic
Characterisation of Simulated Medieval Paint Films: a Chemometric
Study of the Effects of Natural and UV-Accelerated Ageing
Anuradha Pallipurath,1 Jonathan Skelton,1* Spike Bucklow,2 Stephen R. Elliott1
1
2
Department of Chemistry, University of Cambridge, UK, [email protected]
The Hamilton Kerr Institute, Fitzwilliam Museum, Cambridge, UK
Non-invasive methods for analysing artwork are fast gaining interest due to their facilitating nondestructive and in-situ analyses, without the need for sampling. Raman spectroscopy is one such
technique, and has been widely used for this purpose. Despite being a weak phenomenon, Raman
scattering can give a wealth of information about the chemical functional groups that make up
chromophores, as well as the crystal structures of pigment molecules, from their atomic-vibrational
spectra. This information can not only be used to characterise the materials in, and hence date, artwork,
but can also be used to detect forgeries.
However, during in-situ analyses of artwork, distinguishable Raman scattering from the pigment can
often be reduced, or even completely masked, by fluorescence from the glazing materials or organic
binders used. While a lot of importance has been given to the study of pigments, identifying the organic
binding materials used has never been an easy task. In addition to fluorescing at visible wavelengths,
most binders also have characteristic vibrational-spectroscopy peaks in the same spectral regions, e.g.
corresponding to C-H and carbonyl stretches, making their differentiation challenging. Previously,
we have shown that the use of multiple spectroscopic data sources, e.g. FT-Raman and fibre-optic
reflectance spectra, together with multivariate analysis techniques, not only helps to indentify fatbased binders, but also proteinacious and polysaccharide-based binders, such as gum Arabic and egg,
which are otherwise difficult to differentiate.[1]
In this work, we have extended these techniques to understand the nature of possible interactions
between binders and bound pigments, and to estimate relative concentrations of components in paint
films using FT-Raman spectroscopy. We have also studied naturally and artificially (UV) aged samples
to understand how these interactions change with time. In addition, we have developed chemometric
methods to enable computer-assisted analysis of such spectral data from simulated paint samples, with
a view to working towards an automated identification of paint-binder materials from spectroscopic
data.
Finally, we have also investigated how several different support materials, viz. glass, canvas and
parchment, the latter two of which, like binding media, are organic materials, influence the paint film
spectra and hence the results from our analysis techniques.
References
[1] A. Pallipurath, J. Skelton, P. Ricciardi, S. Bucklow, S. Elliott, J. of Raman Spectrosc. 2013, 44 (6), 866–874.
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OP4
Study of malachite degradation in easel (model) paintings by
spectroscopic analysis
Tanja Špec,1* Klara Retko,1 Polonca Ropret,1,2 Janez Bernard3
Research Institute, Conservation Centre, Institute for the Protection of the Cultural heritage of
Slovenia, +386 1 2343118, (tanja.spec, polona.ropret, klara retko)@rescen.si
2
Museum Conservation Institute, Smithsonian Institution, Suitland, MD, USA
3
Slovenian National Building and Civil Engineering Institute, +386 1 2804204, [email protected]
1
Malachite, copper(II) carbonate [Cu2+2(CO3)(OH)2] is perhaps the oldest green pigment and has been
intensively used in different works of art from Antiquity until late 1800. It has often been proved to be
permanent in oil and tempera paintings, although sometimes brownish hue may appear due to the oil
darkening.[1] The present study describes an interaction between pigment and different binders and an
effect of accelerated aging in easel model paintings which were prepared according to the traditional
Baroque recipes.[2]
Before applied on white gesso ground, colour layers containing malachite, mixed with egg tempera
and/or oil medium were prepared. As finishing protective layers, egg white and mastics were added on
selected areas of the easel painting. The use of different combinations of binders and varnishes enabled
an extended study of different influential factors on pigment degradation. One set of model samples
Figure 1.
a.) A Photomicrograph of the polished cross-section
and location of spot 2 for Raman analysis. b.) A
Photomicrograph of the polished cross section and location
of spot 3 for Raman analysis. c) Raman spectra of Malachite
(1), Copper oxide (2) and Copper oxalate (3).
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OP4
were exposed to the effects of climate parameters variations, such as temperature, relative humidity
and UV-VIS radiation. The other set was left non-aged and it served as the control.
Exposure of model easel paintings to environmental parameters in climate chambers was completed
after two months. On both model paintings, colorimetric measurements were made in order to
determine the differences in colour before and after ageing.
Utilizing Micro-Raman spectroscopy, different green areas of each sample’s cross-section were
analyzed. Supporting analytical methods, such as SEM (Scanning electron microscopy), FT-IR (Fourier
transform infrared spectroscopy) and XRD (X-ray Diffraction) were employed to obtain additional
information on the degradation process of malachite colour layers.
The Raman bands of malachite were determined on all control samples, where the bands are in a
good agreement with literature data.[3] Beside the green particles of malachite, the black particles were
also detected in all of the samples. Nevertheless, much higher proportion of the latter was observed
in the aged samples. Obtained Raman spectra of those particles indicate the presence of a copper
oxide. (Figure 1c, Graph 2).[4] In addition, the scanning electron microscopy (SEM) shows the increased
relative amount of copper on dark particles in respect to green ones. Furthermore, where oil medium
was used as the binder, Raman spectra offered additional results. Beside copper oxide, strong bands
of another compound were recorded at 552, 588, 618 cm-1 (Figure 1b and Figure 1c, Graph 3), which
suggests the presence of a copper oxalate.[5] The formation of oxalates on easel paintings is more likely
to appear in the presence of biochemical activity of lichens, fungi or bacteria[6], which in our study
can be eliminated, due to the known preparation of the model samples and controlled environmental
conditions in climatic chambers. However, some of the previous studies concluded that decomposition
of organic materials, such as proteins, oil, waxes, etc., can also lead towards the formation of oxalic
acid [7], which is most likely the reason for the copper oxalate formation found in the present study. The
presence of oxalate was confirmed also by FT-IR spectroscopy.
References [1] A. Roy (Ed.), Artists’ Pigments. A handbook of their History and Characteristics, vol. 2 Oxford University
Press: New York, 1993, p. 184. [2] R. Hudoklin, Tehnologije materialov, ki se uporabljajo v slikarstvu, vol. 2, Ljubljana, 1958, p. 121.
[3] R. J. H. Clark, P. J. Gibbs, Spectrochim. Acta Part A. 1997, 53, 2159.
[4] L. Debibichi, M. C. Marco de Lucas, J. F. Pierson, P. Küger, J. Phys. Chem. 2012, 116, 10232.
[5] K. Castro, A. Sarmiento, I. Martinez-Arkarazo, J. M. Madariaga, L. A. Fernandez, Anal. Chem, 2008, 80,
4103.
[6] H. G. M Edwards. N. C. Russel, M. R. D Seaward, Spectrochimica Acta Part A. 1999, 53, 99.
[7] N. Mendes, C. Lofrumento, A. Migliori, E. M. Castellucci, J. Raman Spectros. 2008, 39, 289.
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OP5
Portable and laboratory analysis to diagnose the formation of
efflorescence on walls and wall paintings of Insula IX, 3 (Pompeii,
Italy)
Juan Manuel Madariaga,1* Maite Maguregui,2 Silvia Fdez-Ortiz de Vallejuelo,1
Africa Pitarch,1 Ulla Knuutinen,3 Kepa Castro,1 Irantzu Martinez-Arkarazo,1
Anastasia Giakoumaki1
Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque
Country UPV/EHU, Spain, +34946018298, [email protected]
2
Department of Analytical Chemistry, Faculty of Pharmacy, University of the Basque Country UPV
EHU, Spain
3
Department of Art and Culture Studies, University of Jyväskylä, Finland
1
Since the time that any archaeological site is brought to light, it suffers deterioration due in part to rainfall, humidity, water infiltrations, etc., but mainly to environmental stressors. Raman spectroscopy and
other analytical techniques, both portable and laboratory, are increasingly used to identify the deterioration compounds promoted by the reactivity between stressors (acidic gases, microorganisms, etc.)
and original materials that promotes the formation of new compounds (efflorescence or crystallized
salts) like bicarbonates, sulphates and nitrates. In the particular case of the Pompeii site, the impacts
due to the eruption must be added to the others. The APUV expeditions (2010, 2011 and 2012) were
focused on the walls and wall paintings of two houses from Insula IX, 3 (Houses 1,2 and 5,24); some
rooms of greater importance are covered with ceilings but the majority of rooms in both houses are
exposed to the open air. During the expeditions, the nature of the efflorescence in the walls and wall
paintings was evaluated using portable, non-destructive instrumentation. Raman spectroscopy, assisted by diffuse reflectance infrared spectroscopy (DRIFTS) was used to obtain the molecular composition and energy-dispersive X-ray fluorescence (ED-XRF) for the elemental analysis. Some efflorescence
samples were also taken to perform laboratory analysis using the same analytical techniques but also
DRX and SEM/EDX, as well as some mortar samples, detached from the walls, were taken to perform
the soluble salt quantification.
Exposed and protected rooms were measured in spring (May 2010) and summer (September 2011 and
2012), considering different orientations and the walls affected (and not affected) in its back by rainfalls
to observe possible variations in the salts crystallizations. The spring 2010 was with few rainfalls, and
little amount of efflorescence were detected in the walls and practically nothing in the wall paintings of
the protected rooms. The end of August 2011 was rainy and the walls in the protected rooms, especially
those oriented in its back to the main rainfalls, were completely wet; some efflorescence like crystals
were two to five millimeters long. The middle of summer 2012 was also rainy, the walls were not wet
when we performed the measurements, but in this case a notable amount of efflorescence crystals were
evident even in the wallpaintings of the covered rooms.
The CO2 attack on non-protected walls is the greatest decaying phenomena accompanied by rain wash
of the highly soluble metal bicarbonate salts formed after the acid attack (decarbonation of wall paintings and plaster layers till observation of the arriccio mortar). Any bicarbonate salt was measured
in-situ and only calcium, sodium and potassium carbonate (CaCO3, Na2CO3, K2CO3) were identified by
Raman spectroscopy. All of them can be considered original compounds in the mortars; the source for
potassium was found in the own walls, probably coming from the original mortar manufacturing when
using local potassium-bicarbonate type waters.
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In protected wall paintings and walls (rooms covered by roof) higher sulphur contents were observed
(severe sulphation decaying) while a lower amount of sulphur was quantified in exposed walls (partial
dissolution of metallic sulphate salts by rain-washing). Apart from gypsum (CaSO4.2H2O), thenardite
(Na2SO4), mirabillite (Na2SO4.10H2O), aphthitalite (K 3Na(SO4)2) and syngenite (K 2Ca(SO4)2.H2O) were
detected in areas far from the presence of modern mortars and cements used un past restoration processes; sulphates with higher water content were observed in protected rooms where the wall was wet
(2011 expedition), i.e., those having its back in front of the main wind (and rain falls) and belonging to
other rooms without any roofing protection.
Additionally, nitrate salts like lime nitrate (Ca(NO3)2), niter (KNO3) and nitrammite (NH4NO3) were
detected only in protected rooms due to its high solubility. Especially in the expedition of 2011, nearly
pure Raman spectra of niter were collected with the portable instrument, indicating the high concentration of this nitrate in the analysed efflorescence. But the most surprising result was observed in
the 2012 expedition, where niter was in-situ measured in the white efflorescence crystals appearing
through the pigmented layers in wall paintings of several rooms, all of them having well setting roofs.
Chemical modeling and chemometrics were used to explain the results of quantitative concentrations
of ions dissolved from the samples taken to the laboratory. This has resulted in a model that explains
the deterioration process in terms of chemical reactivity, taking into account the orientations of the
walls as well as the covered and not covered situations of the rooms analysed in Insula IX, 3 of the
archaeological city of Pompeii. This model will be presented and discussed.
Acknowledgements
This work was financially supported by the projects DEMBUMIES (ref.BIA2011-28148), funded by the
Spanish MINECO, and Global Change and Heritage (ref. UFI11-26), funded by the University of the
Basque Country (UPV-EHU). The accompanying actions CTQ2010-10810-E (MINECO), AE11-27 (UPVEHU) and AE12-32 (UPV-EHU) supported the expeditions APUV2010, APUV2011 and APUV2012 respectively.
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Decorated plasterwork in the Alhambra investigated by Raman
spectroscopy: field and laboratory comparative study
María José Ayora-Cañada,1* Ana Domínguez-Vidal,1
María José de la Torre López,2 María José Campos Suñol,3
Ramón Rubio Domene4
Department of Physical and Analytical Chemistry, University of Jaén, Spain,
[email protected], [email protected]
2
Department of Geology, University of Jaén, Linares, Spain, [email protected]
3
OTRI, University of Jaén, Spain, [email protected]
4
Conservation Department, Council of The Alhambra and Generalife, Granada, Spain,
[email protected]
1
This work presents the results of the Raman micro-spectroscopic study of decorated plasterworks,
situated on the vaults of the Hall of the Kings in the Lions Palace, at the Alhambra in Granada, Spain.
The Alhambra was built and decorated during the Nasrid period in the XIII-XVth centuries and then
adapted during the first period of Christian domination (XVIth cent). Throughout its history, it has
experienced many transformations, with the most important and generalized restorations taking place
in XIXth century.
The decorated plasterwork under study are the mocarabes or stalactites vaults of the Hall of the Kings.
These are self-supporting domes built up with gypsum. Vertical gypsum prisms applied one over another are joined in multiple different arrays resembling stalactites of a cave. These mocarabes are
decorated with a wide range of colors mainly red, blue, green, golden and black.
Our study has been initiated with a totally non-invasive investigation on the field using a fiber-optic
portable Raman microspectrometer. The works were conducted on scaffolding platforms at a height of
ca. 12 m above the ground level coinciding with conservation works. The portable Raman microspectrometer (B&W Tek InnoRam) was equipped with a 785-nm laser and an optical probe head attached to
a videomicroscope which was mounted on a tripod motorised in the X–Y–Z axes with remote control.
Good quality Raman spectra were obtained during this survey despite working under non-laboratory
conditions (e.g. dust, scaffolding, vibrations, daylight, temperature differences). The main practical
problems encountered had been related to lack of space for probe positioning due to the typical stalactite like disposition of the mocarabes and vibrations of the scaffolding.
The best results of the field investigations were obtained from red decorations where cinnabar and
minium were clearly identified. The position of cinnabar could indicate that this pigment was originally
used by Nasrid artists although it was also used in restorations. On the contrary, minium seems not
to correspond to original decorations. In many areas red colors appeared altered due to degradation
products some of which were identified in situ (like anglesite and calomel).
Furthermore, black decorations showed always the Raman signature of carbon and natural Afghan
lapis lazuli was identified in most of the blue decorated motifs. Synthetic ultramarine blue was detected only in one of the vaults revealing a recent restoration. However, we did not succeed in obtaining
good spectra from green and pale blue-greenish decorations. This is because the laser power had to be
extremely low to prevent photodecomposition due to the strong absorption of the 785 nm laser light by
green pigments and the scaffolding vibrations made difficult the use of measurement times longer than
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a few minutes.
These field studies have been complemented with laboratory studies on microsamples. Microsamples
were carefully taken with a scalped taking into account the information provided by the in situ measurements. They were studied directly by means of a Renishaw (in Via Reflex) Raman microspectrometer coupled to a Leika microscope. The best compacted samples were selected to prepare thin cross
sections by embbeding with epoxy resin. With this approach the stratigraphy of the decorations can
be also investigated. In this way, we could confirm our previous hypothesis: in several samples a first
pictorial layer of cinnabar applied over the gypsum substrate appeared covered by a second pictorial
layer of minium. Furthermore, using a 514 nm laser the pale-blue pigment was identified as azurite.
Degradation products like calcium oxalates probably formed through microbial degradation of the organic materials employed as binders.
In conclusion, the complementary information provided by field measurements with the portable spectrometer and laboratory measurements especially on thin cross sections has allowed a good understanding of the pigments and other materials employed for the decoration of the plasterwork in this
Hall of the Alhambra as well as the several degradation phenomena that are taking place.
Figure 1. Detail of the Raman probe head with the
microscope during measure
Acknowledgements
This work was financed by the research project CTQ2009-09555 from the Ministry of Science and
Innovation. The Council of the Alhambra and Generalife, PAIDI Research Groups FQM 363 and RMN
325 are also acknowledged for supporting this project.
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Multi-technical approach for the study of French Decorative Arts
furniture and luxury objects
Céline Daher,1 Ludovic Bellot-Gurlet,2 Céline Paris,2 Juliette Langlois,1
Yannick Vandenberghe,1 Jean Bleton,3 Anne Forray-Carlier,4
Anne-Solenn Le Hô1 *
Centre de Recherche et de Restauration des Musées de France (C2RMF), Palais du Louvre – Porte
des Lions, Paris, France, +33 1 40 20 24 22, [email protected], [email protected]
2
Laboratoire de Dynamique, Interactions et Réactivité (LADIR), UMR7075, UPMC-CNRS, Paris,
France
3
Laboratoire d'Études des Techniques et Instruments d'Analyse Moléculaire (LETIAM), IUT d'Orsay,
Orsay, France
4
Musée des Arts Décoratifs, Les Arts Décoratifs, Paris, France
1
During the eighteenth century in Europe, a trend in the furniture field was to imitate the Asian lacquers,[1] known as exceptional for their great aesthetic beauty and gloss (Figure 1), and the delicate and
fine ornaments. Four brothers, “les frères Martin” were considered as the most famous painters, gilders
and varnishes in Paris, and used to work, followed by their descendents, at the royal court of Louis XV.
Their work was dedicated to different types of objects, such as household furniture, small boxes for
perfumes or make-up, wooden wall paneling, or even sledges and coaches. Their art of imitating Japanese and Chinese lacquers required the development of different painting and varnishing techniques,
based on European familiar material, and became famous for its high and fine quality.
The Martin’s particularity was to apply a specific varnish “Vernis Martin” [2] on multilayered painted
background, on wooden, papier mâché or metallic artifacts. The composition of the varnishes and
paints, the different used materials (resins, pigments, dyes, etc.), and in a larger point of view, the
Martin’s painting and varnishing techniques, have not been studied yet. These varnishes, or to a larger
extent, European lacquers are complex systems made of a colored background, covered with a number
of transparent layers.[3,4] Then, colored or gilded ornaments are applied, representing different characters, flowers, or landscapes. The aim of this project was to improve the varnishing techniques knowledge in the Decorative Arts field during the 18th century to enrich the history of art and techniques,
and to have a better conservation strategy of such fancy objects.
Figure 1. Photography of a French imitation
of Japanese artwork. Inv57965, Musée des Arts
Décoratifs, Paris.
In order to reveal this unfamiliar complex system and the Martin’s specific technique, and to characterize the employed materials, a combination of analytical techniques was set up. Among these techniques, some were non-destructive such as Raman, FT-Raman and infrared in reflectance mode,[5]
used to identify the varnish composition and the dyes employed for the painted areas directly on the
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object, or on micro-samples taken from lacunar areas of the artifacts. Other methods were employed to
complete the organic analyses (GC/MS, py-GC/MS) or to characterize the mineral compounds (SEM,
micro-diffraction).
The presented results are mainly the vibrational analyses ones, on which specific spectral treatments
[6]
were applied in order to extract detailed information and a better molecular identification thanks
to these vibrational signatures. A synthetic overview of the whole obtained data is given, showing the
singularity of these complex European preparations not or poorly studied.
Acknowledgements
The authors would like to thanks the different museums which collaborated to this project, giving
access to all the studied objects: musée des Arts Décoratifs (Paris), musée du Louvre (Paris), and Le
Château de Versailles. This work has been financially supported by the foundation “Sciences du Patrimoine” and Labex “Patrima”.
References
[1]A.-S. Le Hô, M. Regert, O. Marescot, O., C. Duhamel, J. Langlois, T. Miyakoshi, C. Genty, M. Sablier, Anal.
Chim. Acta. 2012, 710, 9.
[2]J. F. Watin, L’art de faire ou d’employer les vernis, ou l’art du vernisseur, Quillau, Paris, 1772.
[3]A.-S. Le Hô, E. Ravaud, J. Langlois, A. Mathieu-Daudé, E. Laval, A. Jacquin, I. Chochod, M. Bégué, J.
Mertens, M.-L. Deschamps, A. Forray-Carlier, ICOM Committe for Conservation: 16th Triennial Meeting,
Lisbon, Portugal,19-23 September, 2011, Preprints, electronic format 2011 (CD-ROM).
[4]A. Rizzo, Anal. Bioanal. Chem. 2011, 392, 47.
[5]W. Vetter and M. Schreiner, e-Preservation Science. 2011, 8, 10.
[6]C. Daher, PhD thesis, Université Pierre et Marie Curie (UPMC), 2012, available online: http://tel.archives-ouvertes.fr/tel-00742851/
RAA 2013
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P1
Deterioration of lead based pigments on a fresco: a micro-Raman
investigation
Ilaria Costantini,1 Antonella Casoli,1 Daniele Pontiroli,2 Danilo Bersani,2
Pier Paolo Lottici 2*
Chemistry Department, University of Parma, Italy,
+39 0521 905425, [email protected]
2
Physics and Earth Sciences Department, University of Parma, Italy,
+39 0521905238, [email protected]
1
Micro-Raman spectroscopy analyses were carried out on some pictorial fragments taken from a portion
of the fresco in the Chapel of St. Stephen, situated in Montani (BZ), Val Venosta, Italy, and painted
around 1430. Within this building, especially on the apse and on the vault, an alteration of lead based
pigments is clearly visible, as a dark coating. The lead pigment was presumably mainly white lead, used
to create highlights and light and dark effects. Samples were taken from altered blackened areas and
from areas cleaned according to the traditional method of conversion of white lead, using a solution
of acetic acid and hydrogen peroxide in cellulose pulp. The “cleaned” samples appear in their original
colors, yellow and green. The samples taken from cleaned areas show characteristic spectra of leadtin yellow pigments, both type I and type II, identified predominantly from green samples. Goethite,
hematite, celadonite green earth, and lapis lazuli
have also been found.
The Raman spectra have been taken at very low (< 0.1 mW) laser
power due to the complex behaviour of lead oxides for photothermal effects induced by the laser excitation (here 632.8 nm).
[1]
The micro-Raman spectra from blackened degraded samples
give no evidence of white lead but show always a structured wide
band centered at about 515-520 cm-1 which can be attributed to
the presence of plattnerite (PbO2), well known alteration product
of lead based pigments, especially in presence of moisture and
in strongly alkaline environment. The Raman spectra are nearly
insensitive of the laser power and very often show PbO (litharge/
Figure 1. Raman spectrum of the black
massicot) features of varying intensities. Other features at about
-1
-1
degradation material a.) compared with
230 cm and 600 cm cannot be attributed to lead oxide phases,
that of plattnerite b.). c.) and d.) are Raman
litharge or massicot (Figure 1). On the other hand, starting from
spectra (massicot and litharge, respectively)
synthetic plattnerite, lead oxides (red lead Pb3O4, litharge and
obtained by laser photo-degradation of
massicot) are obtained at increasing laser power (Figure 1).
plattnerite.
The nature of the dark degradation material is discussed on the
basis of Raman and XRD results and on degradation tests on
white lead, with different binders.
References
[1] L. Burgio, R. J. H. Clark, S. Firth, Analyst, 2001, 126, 222–227.
35
Book of Abstracts
P2
Investigation of colour layers in easel (model) paintings influenced
by different ageing process
Klara Retko,1* Tanja Špec,1 Polonca Ropret,2
Research Institute, Conservation Centre, Institute for the Protection of Cultural Heritage of
Slovenia, Ljubljana, Slovenia, +386 1 2343118, [email protected], [email protected]
2
1
Investigation of deterioration and material degradation on works of art has a great impact in designing
better conservation and preservation procedures. Colour layers stability depends to a great extent on
the individual stability of a pigment and binder, and possible pigment-binder interactions. Influential
factors such us UV-VIS radiation, pollutants exposure, and humidity and temperature oscillation may
also accelerate degradation processes.
In this study, changes of physical and chemical properties of different colour layers as a consequence
of degradation are presented. For that purpose several easel (model paintings), containing different
colour layers were prepared in which all materials selected for the preparation of model samples corresponded to the materials used in the Baroque period.[1] Therefore pigments such as lead white, lead tin
yellow (type I), prussian blue, smalt, azurite and vermilion were employed. Each pigment was mixed
with egg tempera or oil medium and applied on a gesso ground.
Model samples were then exposed to artificial accelerated ageing process for a period of two months,
using well-controlled climatic chambers. One set of model easel paintings was exposed in the climatic
chamber where oscillations of temperature and relative humidity were performed, while the other set
of samples was exposed to the UV-VIS radiation. The last set of model samples was left non-aged and
served as control.
Figure 1. Raman spectra of non-aged azurite colour layer (AZ_
B2_REF) and azurite colour layers after T,RH (AZ_B2_T,RH)
and UV-VIS exposure (AZ_B2_UV-VIS). In all presented
samples, linseed oil (B2) was selected as the binder.
Utilizing Micro-Raman spectroscopy all colour
layers were examined. The main differences in
Raman spectra of aged and non-aged samples
that indicate possible degradation process were
observed in azurite and lead white containing
colour layers.
After completed accelerated aging process of
blue azurite colour layers, greenish hue has
been observed. According to literature data, conversion of blue pigment azurite (Cu3(CO3)2(OH)2) to the
green pigment malachite (Cu2(CO3)2(OH)2) is possible, although mechanism is not well understood.[2]
The Raman bands at ~ 153, 180, 220, 269, 354, 432, 1055, 1091 and 1491 cm-1 revealed the presence
of malachite[3] (Figure 1), interestingly, only in colour layers prepared in oil medium, and after both
exposures (UV-VIS and T, RH). It is possible that the presence of malachite stems from azurite converRAA 2013
36
P2
sion, which appears to be less stable in the medium with higher amount of fatty acids. In cases, when
azurite was mixed with lead tin yellow and lead white, it showed a lower stability in the egg tempera
after exposed to UV-VIS radiation. To acquire additional knowledge on mechanism of reactions further
research is necessary.
In lead white colour layers, which were prepared with both binders and exposed to UV-VIS radiation
changes in Raman spectra were observed The additional band at 967cm-1 (Figure 2) can be assigned to
ν(SO42-). It is possible that the lead white interacted with a sulphate containing compound.[4]
While the easel painting have not been exposed to air pollutants, such as SOx, which could initiate
the formation of sulphates, the source of sulphates is possibly contributed to gypsum (CaSO4·2H2O),
present in the ground layer. Interestingly, the effect was observed only after UV-VIS exposure and not
under humid conditions. However, additional research needs to be carried out.
Figure 2. Raman spectra of non aged lead white colour
layers prepared with egg yolk (LW_B1_REF) and linseed oil
(LW_B2_REF) and after UV-VIS exposure (LW_B1_UV-VIS,
LW_B2_UV-VIS).
References
[1] R. Hudoklin, Tehnologije materialov, ki se uporabljajo v slikarstvu, vol. 2. Ljubljana, 1958, p. 121.
[2] A. Lluveras, S. Boularand, A. Andreotti, M. Vendrell-Saz, Applied Physics A. 2010, 99, 363.
[3] R. J. H. Clark, P. J. Gibbs, Spectrochimica Acta Part A. 1997, 53, 2159.
[4] E. Kotulanová , P. Bezdička, D. Hradil, J. Hradilová, S. Švarcová, T. Grygar, J. Cult. Her. 2009. 10, 367.
37
Book of Abstracts
P3
Identification of copper azelate in 19th century Portuguese oil
paintings: Characterisation of metal soaps by Raman Spectroscopy
Vanessa Otero,1,2 Diogo Sanches,1, 2 Cristina Montagner,1, 2 Márcia Vilarigues,1, 3
Leslie Carlyle,1, 2 Maria J. Melo1, 2*
Departamento de Conservação e Restauro, Faculdade de Ciências e Tecnologia, Universidade Nova
de Lisboa, Portugal, [email protected]
2
REQUIMTE-CQFB, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal
3
VICARTE, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal
1
Several 19th century oil paintings by the artist Tomás da Anunciação (1821-1879) who is considered
a prominent figure of Portuguese romanticism were studied. The identification of the green pigment
used in the trees and foliage was not straightforward. The presence of copper in cross-sections was
confirmed by micro-Energy Dispersive X-ray Fluorescence (µ-EDXRF) and Scanning Electron Microscopy coupled with an Energy Dispersive X-ray Spectrometer (SEM-EDS). The green particles were then
characterised by micro-Fourier Transform Infrared Spectroscopy (µ-FTIR) and Raman Microscopy
(µ-Raman). The infrared fingerprint does not match a copper resinate, but it was possible to detect a
band at 1586 cm-1 attributed to the asymmetric COO - stretching of copper carboxylates [1,2]. The detection of these compounds was also confirmed by µ-Raman through the identification of bands at 1440
cm-1 and 1296 cm-1 assigned to CH2 bending. This indicates a reaction between the copper pigment with
the surrounding oil binding media [2,3].
Based on these findings, it was decided to test a new set of metal soaps synthesised in the laboratory.
The synthesis method was adapted from Robinet and Mazzeo [1, 4]. Metal salts of lead, zinc, calcium,
cadmium, copper and manganeseII were used and the carboxylic acids chosen were palmitic, stearic,
azelaic and oleic acids. Characterisation was performed by µ-FTIR, µ-Raman and X-ray Diffraction
(XRD) and it is anticipated that these results will be of great value for in situ detection of metal soaps
by µ-Raman.
The distinction between the saturated carboxylates, copper
palmitate and stearate, is not straightforward. The application of a chemometrics approach based on µ-Raman data, for
the discrimination of the type of carboxylate, was tested and
will be discussed.
In contrast, copper azelate and oleate show distinct spectra
by µ-Raman as well as by µ-FTIR. Copper azelate shows a different Raman CH2 bending profile and different characteristic bands for C-C stretching and bending. As may be seen in
figure 2, the green degradation product detected on Tomás
da Anunciação oil paintings matches the copper azelate
µ-Raman spectrum. Its identification was also confirmed by
µ-FTIR on a very small green micro-sample, free from lead
white. It was possible to identify both the asymmetric and
symmetric COO - stretching of copper azelate at 1586 cm-1 and
RAA 2013
38
Figure 1. Oil painting on canvas entitled Paisagem
e Animais (1851) from Tomás da Anunciação.
P3
1417 cm-1, respectively.
Acknowledgements
This work has been financially supported by national funds through FCT- Fundação para a Ciência e
a Tecnologia under the project PTDC/EAT-EAT/113612/2009. We also thank FCT-MCTES for Vanessa
Otero’s PhD grant SFRH/BD/74574/2010, Cristina Montagner’s PhD grant SFRH/BD/66488/2009 and
Diogo Sanches’s PhD grant, SFRH / BD / 65690 / 2009. We would also like to thank the curator of The
Museu Nacional de Arte Contemporânea – Museu do Chiado, Maria de Aires, for her collaboration.
Figure 2. Raman spectra of a.) green area of a cross-section taken
from Paisagem e Animais oil painting of Tomás da Anunciação,
b.) copper azelate and c.) copper palmitate.
References
[1] L. Robinet, M. Corbeil, Sudies in Conservation. 2003, 48, 23–40.
[2] M. Gunn, G. Chottard, E. Rivière, J. Girerd, J. Chottard, J. Studies in Conservation. 2002, 47, 12–23.
[3] J. J. Boon, F. Hoogland, K. Keune, AIC paintings specialty group postprints: papers presented at the 34th
annual meeting of the AIC of Historic & Artistic Works providence, Rhode Island, 16–19 June, 2006. AIC:
H. M. Parkin, Washington, 2007, pp. 16–23.
[4] R. Mazzeo, S. Prati, M. Quaranta, E. Joseph, E. Kendix, M. Galeotti, Anal. Bional. Chem. 2008, 392, 65–
76.
39
Book of Abstracts
P4
Raman study of pigment degradation due to acetic acid vapours
Alessia Coccato,1* Nathalie De Laet,2 Sylvia Lycke,1,2 Jolien Van Pevenage,2
Luc Moens,2 Peter Vandenabeele1
1
2
Department of Archaeology, Ghent University, Belgium, [email protected], [email protected]
Department of Analytical Chemistry, Ghent University, Belgium
The conservation of works of art that consist of different materials is complicated as the component
materials are not equally sensitive to the same environmental conditions. Humidity, light exposure
and temperature are known to be dangerous to cultural heritage objects, favouring their degradation
through physical, chemical and biological processes. These factors can be easily controlled, especially
when the work of art is placed at display in a museum, with limited air circulation, controlled humidity,
and temperature.
Nevertheless, display cases with wooden parts may cause further damage to their content, because
of the release of acetic and formic acid.[1] This evidence has been highlighted by many studies,[2-4] and
proved to be itself sensitive to humidity and temperature conditions.
For conservative purposes, it is necessary to study also the contribution of acid organic pollutants to
the degradation of the materials present in a work of art. Studies are currently performed on pigments,
varnishes, leather, parchment, paper and textiles, in the frame of the European FP-7 project MEMORI.
Our research is focused on pigment degradation and on the development of a passive air sampler
coupled to a dosimeter reader, which is the MEMORI-dosimeter, to monitor the combined effects of all
the conditions to which the art object is exposed (climate, organic and inorganic vapours).
The pigment selected for this study are malachite (Cu2(CO3)(OH)2), lead white (Pb2(CO3)(OH)2), red lead
(Pb3O4), lead-tin yellow type I (Pb2SnO4) and pigment orange 36 (C17H13ClN6O5). Different acetic acid
atmospheres were produced to simulate the release of organic pollutants from wood in closed cases.
Five samples of each pigment were kept in the closed vessels and monitored over 5 weeks.
The evaluation of the effects of acetic acid were checked both as a change in colour, and with Raman
spectroscopy. Samples were analysed with a Kaiser Hololab 500R spectrometer (λ=785 nm) or a
Bruker Senterra spectrometer (λ=532 nm). To take sample inhomogeneity into account, 100 spectra
were recorded for each sample, and the results were averaged. Here we present some results for leadtin yellow (type I). The spectrum of the original pigment is in good agreement with literature (top
spectra in Figure 1 and Figure 2) is in good agreement with literature,[5] while it is possible to notice
the appearance of new bands (652, 924, 1337, 1422, 2940 cm-1) and sometimes the decrease in intensity
of some bands (452 cm-1) in relation with increasing dose (time x concentration), as can be seen in
Figure 1. No shifts in the band positions were noticed. The newly formed bands can be ascribed to the
formation of acetate salts of lead (II). It seems that acetic acid does not affect the ν(Sn-O) vibration at
194 cm-1, while the ν(Pb-O) stretching band at 452 cm-1 decreases in intensity, suggesting the formation
of lead acetate and tin dioxide. The white colour of lead acetate is responsible for the lightening of
the yellow tint. The studied pigments showed a different sensitivity towards the aggressive acetic acid
atmosphere, some of them being reactive but showing no change in colour (lead acetate is white, as
well as basic lead carbonate[6]), some showing strong colour changes (lead-tin yellow type I becomes
paler,[7] malachite turns to a bluish-green shade because of the formation of verdigris,[7] red lead darkens
probably in relation to the formation of the black lead(IV) oxide plattnerite [8]), finally pigment orange
36 showed no changes in colour nor in the vibrational spectrum.
Raman spectroscopy demonstrated once more its effectiveness in the characterization of pigments
and their degradation products, in this case in combination with digital photography and RGB
measurements.
RAA 2013
40
P4
Acknowledgements
The authors wish to acknowledge the MEMORI project for their financial support and for the
interesting discussions with the colleagues. The MEMORI, ‘Measurement, Effect Assessment and
Mitigation of Pollutant Impact on Movable Cultural Assets. Innovative Research for Market Transfer‘,
project is supported through the 7 Framework Programme of the European Commission (http://www.
memori‑project.eu/memori.html).
Figure 1. Left: Effect of time on lead tin yellow type I exposed to 33% acetic acid vapours. From top to bottom: pure
pigment, after one, three and five weeks of exposure. Right: Effect of increasing concentration of acetic acid on lead tin
yellow type I, after four weeks of exposure. From top to bottom: pure pigment, 9%, 20% and 33% acetic acid atmosphere
References
[1] W. Hopwood, T. Padfield, D. Erhardt, Science and Technology in the Service of Conservation. 1982, 24–
27.
[2] T. Baird, N. H. Tennent, Studies in Conservation. 1985, 30, 73–85.
[3] C. Laine, Structures of Hemicelluloses and Pectins in Wood and Pulp. University of Technology: Helsinki,
Espoo, Finland, 2005.
[4] L. T. Gibson, Corrosion Science. 2010, 52, 172–178.
[5] I. M. Bell, R. J. H. Clark, P. J. Gibbs, Spectrochimica Acta Part A. 1997, 53(12), 2159–2179.
[6] J. E. Svensson, A. Niklasson, L.G. Johansson, Corrosion Science. 2008, 50, 3031–3037.
[7] G. Calvarin, N. Q. Dao, J. P. Vigouroux, E. Husson, Spectrochimica Acta Part A. 1982, 38, 393–398.
[8] D. A. Scott, T. D. Chaplin, R. J. H. Clark, J. of Raman Spectroscopy. 2006, 37, 223–229.
[9] L. Burgio, R. J. H. Clark, S. Firth. The Analyst. 2001, 126, 222–227.
41
Book of Abstracts
P5
Investigating the sources of degradation in corroded lead sculptures
from Oratory Museum (Museu do Oratório), Brazil
Thiago Sevilhano Puglieri,1 Dalva Lúcia Araújo de Faria,1*
Luiz Antônio Cruz Souza2
1
2
Instituto de Química, Universidade de São Paulo, Brazil, +55 11 30913853, [email protected]
Lacicor – Laboratório de Ciência da Conservação – Escola de Belas Artes, Universidade Federal de
Minas Gerais, Belo Horizonte, MG, Brazil
The presence of acetic and formic acids and formaldehyde, combined with inadequate environmental
conditions, as high relative humidity (RH) and temperature, constitute a very threatening scenario for
the integrity of materials such as metals [1-3]. Wood is a common source of such volatile organic compounds and its use in showcases should be avoided. However, Pb sculptures from Oratory Museum
(Museu do Oratório) at Ouro Preto, in the Brazilian state of Minas Gerais, exposed inside glass showcases presented an increasing degradation (Figure 1) and the corrosion sources were to be identified to
stop further damage.
Small fragments of the corrosion products, a whitish hair-like material, were collected and analyzed by
Raman microscopy, stereomicroscopy, SEM-EDX, FTIR and XRD. Raman spectroscopy was also used
to test possible sources of pollutants.
Stereomicroscopy confirmed the formation of crystals, excluding the possibility of a fungi attach, while
SEM-EDX also revealed the presence of Pb, C and O. XRD detected basic lead carbonate and Raman
microscopy showed the formation of Pb carbonates and formates (Figure 2).
The glass showcases were mounted on a painted steel baseplate and, thus, the considered formate
sources were the paint used and glass cleaning products. Formaldehyde was widely used as preservative in house-keeping products and, although in Brazil this practice is prohibited since 2008, its use in
Figure 1. Corroded polychrome lead
Figure 2. Raman spectra (632.8 nm) from different
sculptures of Museu do Oratório.
areas of samples collected from the analyzed polychrome
lead sculpture.
RAA 2013
42
P5
informal market products is common. An investigation was then carried out on the effects of the paint
and glass cleaning products used in the Museum on Pb coupons under controlled conditions (100% RH
and 23 ± 2 ˚C).
When Pb coupons were exposed to environments containing the fresh paint at 100% RH only carbonates were detected in the corrosion layer, while the coupons exposed together with the cured paint
showed the presence of carbonates and formates. Only carbonates were found on the Pb coupons when
commercial glass cleaning products were tested (Veja Vidrex® and Cif®) but with a street marketed
cleaning product, formates were produced on the metal surface.
The results here reported highlight the importance of a careful evaluation of commercial products,
particularly cleaning products and paints, aimed to be used inside museums or other institutions that
keep artworks or cultural heritage items, considering the potential risk of harmful volatile compounds
release that can cause significant damage in the artworks and objects in general.
References
[1] A. Niklasson, L. G. Johansson, J. E. Svensson, Journal of the Electrochemical Society. 2007, 154, C618.
[2] J. Tetreault, E. Cano, B. M. Van, D. Scott, M. Dennis, M. G. Barthes-Labrousse, L. Minel, L. Robbiola, Studies in Conservation. 2003, 48, 237.
[3] D. L. A. de Faria, A. Cavicchioli, T. S. Puglieri, Vibrational Spectroscopy. 2010, 54, 159.
43
Book of Abstracts
P6
Evora Cathedral: Pink! Why not?
Tânia Rosado,1 Andreia Reis,1 António Candeias,1 José Mirão,2
Peter Vandenabeele,3 Ana Teresa Caldeira1*
HERCULES Laboratory and Evora Chemistry Centre, Évora University, Portugal, +351 266745300,
[email protected], [email protected], [email protected]
2
HERCULES Laboratory and Evora Geophysics Centre, Évora University, Portugal, +351 266745300,
[email protected]
3
Gent University, Department of Archaeology, Gent, Belgium, +09 264 47 17,
[email protected]
1
Evora Cathedral or Santa Maria Church is one of the most emblematic monuments in Evora, a Southern
Portugal monumental town classified by UNESCO as World Heritage. This monument is the biggest
Portuguese Cathedral and has a Romanic-Gothic style, or Gothic with Cistercian and Medicant
influences. Its construction dates back to the 13th century and was inspired in the model of Lisbon’s
Cathedral and other foreign cathedrals.
This monument has suffered several conservation and restoration interventions through the ages,
without, however, any type of previous knowledge about the type of mortars and materials used.
Recent works [1,2] focused on the material characterization of the renders, have shown that the inner
walls of the Cathedral are composed of dolomitic aerial lime mortars with siliceous aggregates similar
in composition to the granodiorites of Evora’s region with crushed ceramics as additives which can
be dated back to a 16th century documented rehabilitation intervention. These works, however, were
unable to detect any pigment and hence to explain the pink colour that covers the majority of the inner
walls surface. The present work reports our search to explain the pink colour of Evora Cathedral inner
walls. An integrated approach was envisaged to explore the anthropic or natural sources of the walls
pink colour by combining the material characterization of the surface layers with its microbiological
study.
Several micro-samples of the surface layer were collected with a small chisel for material characterization
by scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS),
micro-Raman spectrometry and micro X-ray diffraction.
For the microbiological assays, samples were aseptically collected in pink areas of the walls, followed
inoculation in selective media for microorganisms development. The identification of the microbial
isolates was performed based on the macroscopic and microscopic features. Microfragments of mortars
were further analised by SEM-EDS and micro-Raman spectrometry[3–5] to understand the proliferation
of the microorganisms and to characterise the chromatic and microstructural alterations observed in
the walls.
As expected, the material characterization showed no presence of inorganic chromophores and
therefore the use of pigments in the mortars.
The microbiological study, however, allowed the identification of several bacterial strains (eg Gram+
cocci/bacilli), 3 yeast strains in particular one of the genera Rhodotorula and filamentous fungi, 5
strains of the genera Penicillium, one strain of the genera Cladosporium, mycelium and sterile micelia
were also isolated.
Particularly relevant was the fact that, the predominant isolated microrganism colonies, Rhodotorula
sp yeast, exhibited a strong pink / dark orange colour that was further investigated to establish the
RAA 2013
44
P6
effect of its growth on the mortars by different sets of experiments:
- Innoculation of Rhodotorula sp yeast on mortar test specimens for microorganisms proliferation
evaluation,
- Insertion of original historical mortar on sterilized liquid culture media under controlled conditions
for detection of metabolic compounds,
- Liquid cultures of isolated Rhodotorula sp yeast for production of metabolic compounds.
A)
C)
B)
Figure 1. a.) Detail of the inner wall of the Évora Cathedral with the SEM
micrograph of the mortar with the yeast b.) Isolated yeast culture c.) Raman
spectrum of mortar microsample biological contaminated with carotenoids peaks
evidenced (carbon-carbon single-bond stretch vibration (1159 cm−1) and carboncarbon double-bond stretch vibration (1525 cm−1) of the molecule’s backbone).
The envisaged spectroscopic approach on historical and test specimens, and particularly the microRaman spectrometry, allowed evaluating the micro flora proliferation, the presence of oxalates in the
mortars, due to the metabolic activity of the microorganisms and carotenoids detection that can be
attributed to the development of the Rhodotorula sp yeast.
Therefore, the perceived pink color of the Cathedral is due to nature’s process rather than to Human
intention.
Acknowledgements
This work has been financially supported by the Portuguese Science and Technology Foundation (FCT)
through SFRH/BD/65747/2009 PhD grant and contract PEst-OE/QUI/UI0619/2011.
References [1] A. S. Silva, P. Adriano, A. Magalhães, J. Pires, A. Carvalho, A. J. Cruz, J. Mirão, A. Candeias, Int. J. Arch.
Heritage, 2010, 4, 1.
[2] P. Adriano, A. Santos Silva, R. Veiga, J. Mirão, A. E. Candeias, Materials Characterization, 2009, 60, 610.
[3] J. R. Goodwin, L. M. Hafner, P. M. Fredericks, J. Raman Spectrosc. 2006, 37, 932.
[4] S. E. J. Villar, H. G. M. Edwards, M. R. D. Seaward, Spectrochimica Acta Part A. 2004, 60, 1229.
[5] H. G. M. Edwards, E. M. Newton, J. Russ, J. Molec. Struct. 2000, 245, 550.
45
Book of Abstracts
P7
Study of red biopatina composition on sandstone from a historical
War Fort in La Galea (Biscay, north of Spain) by means of single
point focusing Raman analysis and Raman Imaging combined with
microscopic observations
Héctor Morillas,1 Maite Maguregui,2 Josu Trebolazabala,1
Isabel Salcedo,3 Juan Manuel Madariaga1*
Country UPV/EHU, Bilbao, Basque Country, Spain, +349 46018298, [email protected]
2
Department of Analytical Chemistry, Faculty of Pharmacy, University of the Basque Country UPV/
EHU, Vitoria-Gasteiz, Basque Country, Spain
3
Department of Vegetable Biology and Ecology, Faculty of Science and Technology, University of the
Basque Country UPV/EHU, Bilbao, Basque Country, Spain
1
For many years, historical buildings have suffered the aesthetical and structural changes caused
by cyanobacteria, algae, etc. colonization. Among building materials used in historical buildings
sandstone is one of the most used materials together with stone, bricks and mortars. This material
can suffer biological colonization and consequently colored biofilms can be formed on its surface,
giving as a result the pathology called biodeterioration. In the literature many authors pointed out
that the biodeterioration process can promote physical and mechanical stress, chemical changes in the
composition of porous building materials, etc. To understand this deterioration process it is important
to study the composition of the newly formed biopatina.
In this work, the characterization of the nature of main carotenoids and their distribution on red
biopatinas formed over the sandstones that constitute the tower in the Fort of Galea, located in Getxo
(Basque Country, North of Spain) was carried out. For that purpose, single point focusing Raman
analysis and Raman imaging was carried out. This spectroscopic technique was also useful to perform
the mineralogical characterization of the sandstone. In order to obtain preliminary results, a portable
Raman instrument was also moved to the place where the fort is located, in order to obtain on site
Raman spectra of the colonized areas. In the laboratory, and additionally to the Raman analysis, the
nature of the main colonizer of the sandstone in the Fort of Galea (see Figure 1-A) was approached
using scanning electron microscopy and phase contrast microscopy.
On site analysis performed over red biopatinas (see Figure 1-B) with the portable Raman instrument
showed the main bands of carotenoids (1526, 1158 and 1006 cm-1). This observation indicate that the
main colonizer of the sandstone is able to excrete carotenoids or it is an organic pigment constituent of
its structure.
Raman analysis performed on the laboratory showed that the main components of the sandstone, which
acts as the support for the colonization, are quartz, iron (III) oxides or oxihydroxides such as hematite,
limonite and lepidocrocite, aluminosilicates such as adularia, ortoclasa, carbon etc. In order to extract
more information about the nature of the main colonizer, samples were observed under phase contrast
optical microscopy and scanning electron microscopy (see Figure 1-C and D).
According to the SEM and optical microphotographs, it can be concluded that an algae is the main
colonizer of the red biopatina that belongs to a genus of filamentous green chlorophyte algae, specifically
in the family of Trentepohliaceae.
Trentepohlia algae can provide a very efficient biological system for harvesting solar energy for the
production of organic compounds through the photosynthetic process. Concretely, the identification
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of β-carotene crystals (see Figure 1-C, D and E) in the pigment globules suggests that the algae have
developed a defense system against photooxidative and oxidative damages. Apart from β-carotene,
scytonemin (see Figure 1-F) was also identified in some areas of the red biopatina. This yellow-brown
pigment is usually present in the extracellular sheaths of cyanobacteria. The presence of this organic
pigment could suggest a combined presence of Trentepohlia and cyanobacteria.
To understand better the distribution of β-carotene and scytonemin over the Trentepohlia, Raman
imaging on β-carotene crystals and scytonemin was carried out.
Figure 1. a.) The Tower of Fort of Galea. b.) A detail of the red colonization on the sandstone of the fort.
c.) Microphotography obtained with the phase contrast microscope showing Trentepohlia alga and its β-carotene crystals in the
pigment globules. d.) SEM microphography showing β-carotene crystal. e.) Raman spectrum of β-carotene and f.) Raman spectrum of
Scytonemin.
Acknowledgements
This work was financially supported by DEMBUMIES (ref.BIA2011-28148) funded by (MINECO).
H.Morillas is grateful to the University of the Basque Country (UPV-EHU) and mainly to the action
UFI 11-26 Global Change and Heritage, who funded his pre-doctoral fellowship.
47
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P8
Raman and non invasive IR analyses of natural organic coatings:
application to historical violin varnishes
Céline Daher,1,3* Ludovic Bellot-Gurlet,1 Stéphane Vaiedelich,2
Jean-Philippe Echard2
Laboratoire de Dynamique, Interactions et Réactivité (LADIR), UMR7075, UPMC-CNRS, Paris, France
Laboratoire de Recherche et de Restauration, Musée de la Musique, Cité de la Musique, Paris, France
3
Centre de Rechercheet de Restauration des Musées de France (C2RMF), Palais du Louvre, Paris,
France, +33 1 40 20 24 22, [email protected]
1
2
During the eighteenth century in Europe, musical instruments’ varnishes have been essentially made
with an oil base (linseed oil, in most cases) to which terpenic resins have been added, such as colophony,
Venice turpentine, mastic, etc [1]. Moreover, these varnishes were sometimes slightly pigmented for
a light red color. The most used approaches determining the composition of ancient varnishes were
based on destructive analyses of micro samples, mainly gas chromatography methods coupled to mass
spectrometry.[2,3] Other analytical approaches, non-destructive and even non-invasive ones, have been
investigated. Indeed, previous studies [4–6] show that Raman and Infrared spectroscopies can identify
and discriminate between natural organic media. The pigments inclusions can also be identify using
vibrational spectroscopies whether for mineral pigments or organic ones.
A first aspect of this study is to characterize historical varnishes by using a totally non-invasive
technique, IR spectroscopy in a specular reflection mode for the varnish analyses.[7] However, using this
unusual mode can present difficulties for the spectra interpretation; the bands have often a derivative
shape,[8] and no databases of such spectra are available yet. In order to get a better understanding
of the obtained spectra and to be able to characterize the vibrational features, the Kramers Kronig
transformation (KKT) has to be applied. In order to validate this new approach, model experimental
varnishes were analyzed both in specular reflection mode then KKT-corrected, and in conventional
absorbance mode, showing that the spectral features were similar.
The studied stringed instruments, kept in the Musée de la Musique in Paris, are from the 18th and early
19th centuries and from different European violin makers: Antonio Stradivari and Giuseppe Guarneri
‘del Gesù’ (Italy), Gabriel Buchstetter and Leopold Widhalm (Germany) and Nicolas Lupot (France).
In situ IR spectroscopy in reflectance mode appeared to be the most suitable non-invasive and nondestructive technique to date to allow the characterization of their organic coatings. The presented
results show the influence of the instrument’s surface aspect (conservation state) on the reflectance
spectra: The more smooth and reflective the object surface is, the better is the signal, which is however
difficult to meet on ancient objects. Nevertheless, it has been possible to positively characterize the
nature of the upper varnish layer, but also the chemical nature of the underlayer, visible on lacunar or
erosion areas.
The second aspect is to characterize the colored red grains by Raman spectroscopy. Tests by portable
785 nm Raman were unfortunately not successful; the fluorescence of the varnish hampered the Raman
signal. Therefore, micro-samples were taken from three instruments by A. Stradivary were analyzed
using a bench top instrument working at 458 nm [9]. The red particles appeared to be a mix between
an anthraquinonic organic pigment (possibly carminic acid) and inorganic iron oxide (hematite).This
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study is a first example of non-invasive analyses of natural organic compounds using IR spectroscopy.
Moreover, post treatments could be applied on the resulting spectra such as spectral decomposition,
in order to get more detailed information of the varnish composition, for instance the different
compounds present in mixtures. On the other hand, we attested the presence of a fine dispersion of
various pigments by Raman spectroscopy, documenting the varnishes coloring techniques. Finally,
the next step of this study would be to try in situ Raman analyses under a micro-spectrometer of the
varnish instrument knowing that the difficulty is actually the moving of these prestigious historical
instruments out of the museum.
References
[1] J.-P. Echard and B. Lavedrine, J. Cult. Herit. 2008, 9, 420.
[2] J.-P. Echard, C. Benoit, J. Peris-Vicente, V. Malecki, J. V. Gimeno-Adelanto, S. Vaiedelich, Anal. Chim. Acta.
2007, 584, 172.
[3] G. Chiavari, S. Montalbani and V. Otero, Rapid Commun. Mass Sp. 2008, 22, 3711.
[4] P. Vandenabeele, B. Wheling, L. Moens, H. Edwards, M. De Reu, G. Van Hooydonk, Anal. Chim. Acta
2001, 407, 261.
[5] C. Daher, C. Paris, A.-S. Le Hô, L. Bellot-Gurlet, J.-P. Echard, J. Raman Spectrosc. 2010, 41, 1204.
[6] L. Bertrand, L. Robinet, S. X. Cohen, C. Sandt, A.-S. Le Hô, B. Soulier, A. Lattuati-Derieux and J.-P.
Echard, Anal. Bioanal. Chem. 2011, 399, 3025.
[7] W. Vetter and M. Schreiner, e-Preservation Science. 2011, 8, 10.
[8] C. Miliani, F. Rosi, A. Daveri, B. G. Brunetti, Applied Physics A. 2012, 106, 295.
[9] J.-P. Echard, L. Bertrand, A. von Bohlen, A.-S. Le Hô, C. Paris, L. Bellot-Gurlet, B. Soulier, A. LattuatiDerieux, S. Thao, L. Robinet, B. Lavédrine, S. Vaiedelich, Angew. Chem. Int. Edit., 2010, 49, 197.
49
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Optical Microscopy and Micro-Raman studies of The Hans
Memling’s Triptych “The Last Judgment
Ewa Pięta,1* Justyna Olszewska-Świetlik,2 Edyta Proniewicz3
Faculty of Chemistry, Jagiellonian University, Kraków, Poland, +48 12 663 22 55,
[email protected]
2
Department of Painting Technologies and Techniques, The Institute for the Study, Restoration and
Conservation of Cultural Heritage, Nicolaus Copernicus University in Toruń, Poland,
+48 056 611 38 22, [email protected]
3
Faculty of Chemistry, Jagiellonian University, Kraków, Poland,
+48 012-663 2077, [email protected]
1
The general aim of this work, that combines chemical and historical knowledge, was Optical Microscopy
and Raman analysis of four multilayered samples taken from four different painting’s parts (three from
the central panel and one from the right wing) of the Hans Memling’s Triptych “The Last Judgment”
(Figure 1). “The Last Judgment” (1467–1471) by Hans Memling is one of the most precious works of
Polish art collections. This outstanding masterpiece belongs to the collection of National Museum in
Gdańsk and has been classified as the netherlandish painting.
The Raman spectra of the painting’s cross-sections taken from
these samples possess a unique set of bands corresponding to
the individual layers [1]. Therefore, these spectra allowed us to
determine the chemical composition of each layer in the crosssection of samples. The following pigments were detected: lead
white, lead tin yellow type I, cinnabar, red ochre, and carbon black.
In all of the cases chalk was used as a ground layer. These results
are precious source of information about main features of school
of painting presented by Hans Memling. Additionally, our results
allow art historians to characterize the influence of different
cultures on the Memling’s artistic work and to plan conservation,
restoration, and preservation procedures of his paintings.
Figure 1. Hans Memling, “The Last
Judgment”, Netherlands school, National
Museum in Gdańsk (photo A. Skowroński).
References
[1] E. Pięta, E. Proniewicz, J. Olszewska-Świetlik, Raman spectroscopy for the identification of pigments,
dyes, and binding media from the Hans Memling Triptych The Last Judgment, in: On the border of
Chemistry and Biology, vol. 29, UAM Press: Poznań, 2012, p. 343.
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Characterization of green copper organometallic pigments and
understanding of their degradation process in European easel
paintings
Carlotta Santoro,1,2* Anne-Solenn Le Hô,2 Sigrid Mirabaud,3
François Mirambet,2 Sandrine Pagès-Camagna,2 Pascal Griesmar,4
Nadège Lubin-Germain,1 Michel Menu2
Le laboratoire de Synthèse Organique Sélective et de Chimie bioOrganique (SOSCO, EA 4505),
CNRS, Université de Cergy-Pontoise, France, +33134257384, [email protected]
2
Centre de Recherche et Restauration des Musées de France (C2RMF), Paris, France
3
Institut National du Patrimoine (INP), France
4
Laboratoire Système de l’Application des Technologies de l’Information et de l’Energie (SATIE), UMR
8029 CNRS, ENS, Université de Cergy-Pontoise, France
1
Verdigris and copper resinate are organometallic complexes of Cu(II). They were widely use as pigments
in XVth and XVIth centuries for their transparency in glazes. These compounds are often subject to
changes with time. There are numerous cases of ageing and darkening, which have caused chromatic
alterations in the appearance and tonality of the paintings.[1]
The understanding of the alteration mechanism, indispensable to orientate the conservation protocols,
is not yet fully elucidate despite several studies.[2,3]
In order to clarify the discoloration process it is necessary to get information on the geometry of the
copper cluster and the nature of the copper-ligand bonds. The observed discoloration of these pigments
has led to the research into the effect of environmental conditions surrounding works of art (light
exposure, T) thanks to natural and accelerated ageing.
With this aim, a multi analytical methodology has been developed coupling the characterization of
real ancient painting samples and model systems (made by various proportion of different pigments
and binding media). Model samples were investigated by a set of analytical techniques before and after
thermic and light ageing: SEM-EDS, IRTF, Raman, UV-Visible, GC-MS, XAS, EPR. The data collected
were compared with those obtained from real samples.
Preliminary results show that copper concentration is constant between alterated and non alterated
zone, and that the darkening seems not influenced by others metals and elements (like calcium, chloride
or sulfur).
The darkening is related to reaction between copper and bi/tri unsaturated fatty acids, while saturated
and monounsaturated compounds are stable.
The alteration is not correlated with hydration of the organometallic complexes but is possibly related
to reorganization of the metallic cluster.
References
[1] C. Altavilla, E. Ciliberto. Appl. Phys. A. 2006, 83, 699-703.
[2] M. Gunn, G. Chottard, E. Rivière, J. J. Girerd, J.C. Chottard, Studies in Conservation. 2002, 47(1), 12-23.
[3] L. Cartechini, C. Miliani, B. G. Brunetti, A. Sgamellotti, C. Altavilla, F. Ciliberto, F. D’Acapito, Appl. Phys.
A. 2008, 92, 243-250.
51
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Non-destructive micro-Raman and XRF investigation
on parade saddles of the Italian renaissance
Pietro Baraldi,1 Davide Gasparotto,2 Claudia Pelosi,3 Paolo Zannini1
Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Italy,
+390592055087, [email protected]
2
Galleria Estense, Superintendence BSAE Modena and Reggio Emilia, Modena, Italy
3
Department of Cultural Heritage Sciences, University of Tuscia, Viterbo, Italy
1
Some parade saddles are preserved in Italian Museums and Institutions with typological and
structural differences on their decorations. Two saddles are observable in the Museum of the Bargello
in Florence and preserve pigments and gildings on their ivory plaques, but enough obscured by the
time patina. One of them is similar to the one in the Estense Gallery: it is one of these special saddles
that is chronologically placed in the time of Hercules’ Dukedom in Ferrara (1471-1505). The aim of
this research was to identify the materials and techniques used in the Renaissance times to prepare
the structure of this kind of saddle, to work the tusks for obtaining the plaques to be carved, to place
the plaques on the structure and to decorate them with pigments, dyes and metal sheets. For the time
elapsed and the exposition in a case in the Estense Gallery, some parts of these aerodynamic structure
may have undergone degradation and alterations and the pigments may have changed they hues as a
consequence of their molecular changes. Therefore, all the structure was examined and an analytical
procedure was prepared so as to take into consideration many materials on the wooden structure.
The surface of the ivory plaques, covering all the surface of the saddle, is almost all well preserved, as
can be observed by carefully inspecting all the details and covered areas, where polychrome survivals
could be present. This visual inspection with a digital microscope led to the identification of small
pigmented areas with bright colours: red, yellow, green blue and black. Some gilding on Hercules’ hair
and on the lion mane can be appreciated.
XRF measurements (Bruker instrument) were taken on all the colours ascertained and on the wood
structure, the parchment intermediate leaves, the white ivory and each coloured small fragments.
Infrared spectra were obtained using a Jasco 4200 Fourier transform spectrometer. The spectral range
was 4000 to 400 cm-1 in ATR mode with 16 scans and a resolution of 4 cm-1.
The micro-Raman spectrometer used in this case was a HE633 transportable from the Jobin YvonHoriba with a spatial resolution of 5 µm and with quick detection ability as a result of the CCD detector
1024x256 pixels cooled to -70 °C by the Peltier effect. The spectral resolution was 10 cm-1. The exciting
wavelength was the 632.8 nm red line of a He-Ne laser. A long distance 50x objective was used.
The different ivory plaques of the Hercules of Este saddle exhibit traces of pigments underlining the
particular detail. The vegetable parts of the carvings are described by a green composed of a copper salt
and an organic part rarely found in artworks. Red is frequently obtained with vermilion, black in the
gothic-like writings is in carbon, but in some points there was also indigotine. Both the mane of the lion
and of Hercules’s hair are obtained with a gold foil perhaps obtained with the usual gold of the florins
of that time. Microscopic details showed the deposition of the gold foil on a whitish preparation with
white lead [2]. Blue areas are obtained with a lightly ground azurite, mainly abraded or fallen from those
surfaces. In the emblem of the Este that contained blue and yellow, only microscopic areas can still be
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seen. Lead white in many small areas was partly transformed into grey plattnerite.
The nails were realized with a copper alloy covered with silver.
The ensemble of techniques applied enabled the series of materials and particularly pigments of the
Hercules’ saddle to be identified. The most difficult one to be identified was the green jelly pigments, an
elaboration of verdigris. This kind of artifact is very attractive and other items should be investigated
in order to find similarities and differences and supposing, also on the basis of artistic and historical
sources, their possible origin.
Acknowledgements
The research could not have been carried out without the permission by the Superintendant BSAE of
the Provinces of Modena and Reggio Emilia, dr. Stefano Casciu.
References
[1] T. Tuohy, Herculean Ferrara, Cambridge University Press: Cambridge, 2009, pp. 187-200.
[2] P. A. Andreuccetti, The polychromy of stone sculptures in Tuscany between the XIII and XV century,
Polistampa Ed., 2008.
53
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P12
Phoenicians preferred red pigments: micro-Raman investigation
on some cosmetics found in Sicily archaeological sites
Cecilia Baraldi,1,* Giada Freguglia,1 Elsa Van Elslande,2 Pamela Toti,3
Pietro Baraldi,4 Maria Cristina Gamberini,1 Claudia Pelosi5
Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy,
2
UPMC - Laboratoire d’Archéologie Moléculaire et Structurale UMR 8220, Paris, France,
[email protected]
3
“Giuseppe Whitaker” Foundation, Palermo, Italy, [email protected]
4
Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia,
Modena, Italy, +390592055087, [email protected]
5
Department of Cultural Heritage Sciences, University of Tuscia, Viterbo, Italy,
1
This research was undertaken in the aim of identifying and getting deeper knoowledge into materials
and pigments used in cosmestics concerning the contest of the phoenician settlements in Sicilian
territory. In fact, about the typologies of cosmetics in use among the Phoenicians, little is known. On
this subject, generally references come from bibliographic latin sources: in antiquity, women preferred
to paint white their face, red lips and cheeks, yellowish eyes and black to sorround their look (Pliny
the Elder, Naturalis Historia; Ovidius, De medicamine faciei feminae). An interesting aspect of this
research is that just one paper is known on Punic cosmetics.[1]
In the Museo Archeologico Regionale “Antonino Salinas” (Palermo, Sicily) an important collection
of unguentaries coming from the town of Selinunte is preserved. Some of them, finely crafted, come
from the sanctuary of Demetra Malophoros, some unguentaries come from the acropolis and some
more from the necropolis (dating from the 6th to the 5th century b. C). The sacred area, excavated by
Cavallari (1818) and Salinas (1903-1905), have provided a great amount of archaeological materials.
In the area where once the acropolis rose, the remains show a mixed village, Phoenician and Greek.
In this study, the findings from Salinas were considered, as well as some others from the Museum
Conte Agostino Pepoli (Trapani), from the Museum Baglio Anselmi (Marsala) and from the museum
of Mozia. The number of glass and fictile unguentaries, pyxis and alabastra examined were large: 142
items from Salinas, 210 from Mozia, 14 from Pepoli and 117 from Baglio Anselmi.
This research has completed the one carried out on 210 samples from the Museum of Whitaker
Foundation from Mozia, a merely phoenician –punic settlement.[2,3]
The samples were analyzed by spectroscopic techniques.
The IR spectra were acquired with a spectrophotometer VERTEX 70 (Bruker) FT-IR, equipped with a
detector deuterium triglycine sulphate (DTGS). The setting parameters were: resolution 4 cm-1, spectral
range 4000-600 cm-1, number of scans 32. ATR spectra were recorded using an Elmer Golden-Gate
accessory.
The micro-Raman spectrometer used in this case was a Labram Model from the Jobin Yvon-Horiba with
a spatial resolution of 1 µm and with quick detection ability as a result of the CCD detector 1024x256
pixels cooled to -70°C by the Peltier effect. The spectral resolution was 1 cm-1. The exciting wavelength
was the 632.8 nm red line of a He-Ne laser.
Generally the samples were presented as inorganic powders of different colors: white, black, blue and
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red. Though the samples came from different museums, they were considered togheter, since they
belonged all to the Phoenician culture and coming from Trapani archaeological sites.
The white samples were of two types. The first one was mainly composed of gypsum and anhydrite
mixtures (e.g. Inv No 1680, 1663, 1753); the other type (e.g. pyxes Inv N° 1393, 1451) was composed of
fully carbonated cerussite, gypsum and litharge. The second kind of cosmetic corresponded to the most
famous Greek cosmetic, called psymition, used by women to white the skin. The first type suggested
that, for the same use, alternative materials, cheaper and most readily available, could be employed in
the past.
The black powders, usually used to outline the eyes, were mostly given by carbon obtained from
vegetable combustion (e.g. Inv. N° 1566, 2314, 4313) or, sometimes, from bone combustion (animal
charcoal) as for the samples Inv. N° 3140, 1761.
A single blue powder (Inv N° 42259) was consisted by the famous Egyptian blue (CaCuSi4O10).
The love for the red color by Phoenician is evident from the great number of powders of this
color, probably used to give color to the cheeks or lips. A wide variety of red minerals was
found. In many cases the presence of hematite (e.g. Inv N° 2309, 2689, 4269) was detected.
A large number of pink and red powders containing cinnabar (unguentaries Inv N° 1393, 6480-1,
34396) was observed. No frequent and very interesting is in fact the HgS finding powder into alabastra
(e.g. Inv. N° 7317/7, 1255), a holder typically used to contain ointments.
Another red pigment was identified as red lead (e.g. Inv N° 1606). Finally, a singular discovery was
the presence of red lead chromates chrocoite and phoenicochroite, two very rare minerals (e.g. sample
Inv. N° 805, 1-98-2, 4386). In fact, they have never been previously attested for cosmetic use, and also
rarely attested in paintings before the end of the 18th century when it began to be produced industrially.
[4]
The high number of Phoenicians samples taken into examination has allowed to understand the
typology of raw materials used by the Phoenicians settled in Sicilian contexts.
In this study affects the materials heterogeneity used for the make-up, even for example in comparison
to the Roman culture, for which there has come a greater number of samples (sites such as Pompeii,
Herculaneum and Oplontis were analyzed by our research group),[5-7] but which revealed a palette less
extensive and less refined. In particular, this study identified the use of many kind of red pigments, also
very rareof mineral origin.
Acknowledgement.
The project couldn’t have been carried out without the kind permission granted by the Superintendence
of Cultural Heritage (Palermo), Museo Archeologico Regionale “Antonino Salinas” (Palermo), Museo
Regionale Pepoli (Trapani), Museo Archeologico Regionale Baglio Anselmi (Marsala).
References
[1] Huqet al., Combined, Appl. Phys. A, 2006, 83, 253–256.
[2] G. Freguglia, C. Baraldi, M. C. Gamberini, P. Toti, P. Baraldi, PRIN07- Colors and balms in antiquity:
from the chemical study to the knowledge of technologies in cosmetics, painting and medicine. Aboca,
Sansepolcro (Arezzo, Italy), 2-3th December 2010, p. 50-51.
[3] Baraldi, G. Freguglia, M.C. Gamberini, P. Baraldi, 5-8th September 2011, RAA2011, Parma, 2011, p. 103104.
[4] R. J. H. Clark. Chimie, 2002, 5, 7–20.
[5] P. Baraldi, C. Fagnano, C. Baraldi, M.C. Gamberini, Automata. 2006, 1, 49.
[6] M. C. Gamberini, C. Baraldi, F. Palazzoli, E. Ribechini, P. Baraldi, Vib. Spectrosc. 2008, 47/2, 82.
[7] E. Van Elslande, M. C. Gamberini, C. Baraldi and P. Walter, An overview of the Raman studies on cosmetic
powders from Pompeii, 14-18th September 2009. RAA2009, Bilbao, 2009.
55
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Raman microscopy and X-ray fluorescence for the rediscovering of
polychromy and gilding on classical statuary in the Galleria degli
Uffizi
Pietro Baraldi,1 Paolo Bensi,2 Alessandro Muscillo,3 Fabrizio Paolucci,3
Andrea Rossi,4 Paolo Zannini1
Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Italy,
+39 0592055087, [email protected].
2
Department of Sciences for Architecture, University of Genua, Italy
3
Ministry for Cultural Heritage, Uffizi Gallery, Florence, Italy
4
Center for Multispectral Analyses, Modena, Italy
1
The Uffizi Gallery in Florence is mainly known for its patrimony of Gothic and Renaissance painting,
but it has also a considerable collection of Greek and Roman statues. The collection is one of the oldest
in Europe and derives from the Medici personal collection and from acquirements during the centuries
and donation from noble families.
Great part of the statuary is not exposed in the Gallery, and in the aim of showing to the public a greater
number of them, the new Museum of Villa Corsini on the hills of Florence was open last year.
All the statue have a long stay in the Gallery and/or in the depositories, so that many need a control
for their present conservation state. Therefore, a research program was set up in order to control the
statues that in turn will be reconsidered for an exhibition or a re-proposal. The items will be studied
firstly as they are, nextly as they will be under cleaning and after cleaning, in such a way to follow
every detail of the surface and to put in evidence the survivals of polychromy, of metal laminas, the
encrustations, the corrosion signs and the biological trace of attack by vegetables.
This program is now in progress and till present the procedure has been applied to some famous
masterpieces placed in the Tribuna. Some of them showed survival of interesting materials that offer
new points for discussion of chronology of art materials and techniques.
Research of this kind is now applied in European Museums and devoted to Greek and Roman statuary.
[1-7]
Figure 1. XRF (left) of the preparation for gilding and
Raman spectra (right) of the yellow layer with Lead tin
yellow type I.
A careful observation of the artwork surface with a digital microscope enabled to identify the points
where microscopic traces of pigment or metal foil were still present. Some portable instrumentation
were used to identify the materials, when their surface was enough large for a specific technique. In
some cases, a microsample was taken and placed in a vial for the analysis in the laboratory. For the
research in progress many analytical techniques were used, especially those that were n-destructive.
The techniques employed were mainly: Raman microscopy, FT-IR spectrometry and microscopy,
X-ray fluorescence spectrometry, Visible induced luminescence (VIL) and multispectral analyses. In
comparing the results obtained from the different techniques care must be taken for the apparent
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inconsistency of some results. Beyond the spectral resolution, spatial resolution must be included. This
comparison could be helpful, for an accurate investigation, by putting in evidence traces of materials
that in other techniques could give only low level signals.
For the Raman spectra portable Jobin Yvon HE633 instrumentation was used, with a 633 nm red laser,
a CCD with 256 x 1024 pixels cooled to -70°C by the Peltier effect. Laser power was at most 5 mW, but
frequently it was reduced to 1/10, and accumulation time was from some few seconds to some minutes.
As a first example, we recall the presence of Lead Tin yellow type I that was identified on the Venere
Medici’s head. It was known that in the 18th century, during the Grand Tour to Italy, the statue exhibited
still a golden hair, subsequently not more observable. Some fragments are still observable, but giallolino
is a new finding for the Roman chronology.
Other interesting founds are traces of lazurite on some sarcophagus, that were neither repainted nor
restored previously, only having been plastered for making the surface uniform and having been
integrated with marble fragments in some parts.
Other interesting findings on sarcophagus were spots of lazurite alternating with aegyptian blue ones clearly
observable con with VIL technique of investigation. Rarely it was also found cinnabar, often on a preparation
with glue and lead white. Multispectral investigation showed details of previous works on the surfaces.
In view of the data here reported, it seems advisable to carry out more investigations on the classical statues
preserved in the Italian Museums. In fact, though their heavy past restoration processes are identifiable, some
survived polychromy can be ascertained with careful inspection and analyses. The combination of the techniques
examined is important since it could supply information on both polychromy and metal foils. The materials used
in the past for gilding can give information on their chronology.
Acknowledgements
This work has been financially aided by the group of »Friends of the Florentine Museums«.
References [1] H. Bankel, P. Liverani, I colori del bianco. Policromia nella scultura antica (The colors of white,
Polychromy in ancient sculpture), De Luca Editori d'Arte: Roma, 2004.
[2] P. Bensi, Recovering the ancient art techniques between the end of Eighteenth and the first decades of
Ninenteenth Centuries, Actes of 3rd seminary “Decennio francese” (1806-1815), Santa Maria Capua Vetere,
10-12 october 2007, Napoli, 2010, p. 101-116.
[3] V. Brinkmann, Die Polychromie der archaischen und frühklassischen Skulptur, Biering & Brinkmann:
Monaco, 2003.
[4] V. Brinkmann, O. Primavesi, M. Hollein, Looking for colour on Greek and Roman Sculpture„ Circumlithio:
polychromy of antique and medieval sculpture“, J. of Art Historiography, 2011, 5.
[5] P. Jockey, B. Bourgeois, La dorure des marbres grecs. Nouvelle enquête sur la sculpture hellénistique de
Délos, J. des savants. 2005, N°2, 253–316.
[6] Ny Carlsberg Glyptotek the Copenhagen Polychromy Network, Tracking colours, The Polychromy of greek
and roman sculpture in the Ny Carlsberg Glyptotek, Preliminary report 1, 2009; Preliminary report 2,
2010; Preliminary report 3, 2011.
[7] R. Panzanelli, The color of life. Polychromy in sculpture from antiquity to present. The J. Paul Getty
Museum – The Getty Research Institute: Los Angeles, 2008.
57
Book of Abstracts
P14
Raman spectroscopic investigation of black pigments
Alessia Coccato,1* Peter Vandenabeele,1 Luc Moens2
Department of Archaeology, Ghent University, Belgium,
2
Department of Analytical Chemistry, Ghent University, Belgium
1
A variety of black pigments were selected for a detailed study by means of Raman spectroscopy. The
well-established and appreciated advantages of this technique for the study of cultural heritage objects,
in the case of black pigments investigation, are mitigated by some difficulties, as the weak scattering
produced by some pigments, and their high absorption of visible light.
The selected pigments cover a wide range of carbonaceous materials, of metal oxides and other materials
(i.e. sepia black, tourmaline), already identified in cultural heritage objects by means of other techniques
(X ray diffraction [1], colorimetry [2], FTIR and SEM-EDS [3]. Old painting treatises provide detailed
receipts for preparing pigments, but ambiguity and misunderstandings in the naming may occur when
matching different authors [4]. Furthermore, just a few studies dedicated to Raman spectroscopy of
carbon black pigments have been published [5], while the study of carbonaceous material of geological
and industrial interest are quite common [6], [7]. The common practice is to use the term “carbon black”
for all the pigments showing two broad bands centred around 1580 and 1300 cm-1, with few exceptions
(e.g. bone/ivory black can be identified if phosphates stretching is present at ~960 cm-1). For metal
oxides, some reference spectra are published in the specific field of archaeometallurgy [8]. For sepia
melanin black pigment only SERS Raman spectra were available for comparison [9], [10]. Tourmaline
black is studied as a mineral and a gem. The aim of our study is to provide an overview of the Raman
spectra of different black artists’ materials and to propose a nomenclature.
Figure 2. Raman spectra of selected black pigments, from top to
bottom: powdered ivory black, ivory black in pieces and spinel black.
Raman spectra were collected using a Bruker Senterra spectrometer, equipped with two excitation lines
(532 and 785 nm). As expected, the spectra of carbon blacks are all quite similar to each other, with
two broad bands centred at 1580 and 1320 cm-1, but some differences may be highlighted. Obviously, a
single crystal of graphite gives a recognizable spectrum, with narrow an well separated bands; but as
the disorder in the solid phase increases, bands shift and new ones arise, in addition to the G (1580 cm1
) and D1 (1350 cm‑1) bands [7], so the deconvolution process for estimating the band position and width
has to take this into account. Moreover, some pigments had additional bands in their spectra. In some
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cases these were helpful in identifying particular types of carbon black, as carbonates in Black Earth
from Andalusia, which is supposed to be a mixture of carbonaceous materials with quartz and calcite,
or as in the case of the phosphate vibrations, that indicates a black derived from bones calcination
(Ivory black). But in some other cases some unexpected bands showed up, revealing the presence of
contaminants in specific carbon black pigments. Specifically, it was possible to identify Spinel Black
bands together with others, as in Black Chalk, whose composition is not well defined, and also in Sepia,
Ivory black and in Graphite powder (Figure 1). For these latter samples, the presence of such materials
is highly unexpected.
As regards to metal oxide black pigments (iron and manganese, mainly), it has been noted that high
laser power (1,4 mW for 532 nm line, 7,4 mW for 785 nm line) induces a red coloration of the Mars Black
Iron Oxide 318 pigment, and burns Manganese black. Good quality spectra were generally obtained
with green excitation, at its lowest possible power, with long measurement times.
The first results of this research confirm the effectiveness of Raman spectroscopy in the study of dark
pigments, as the possibility of identifying many black pigments through a non-destructive technique
and of distinguishing among different carbon blacks.
References
[1] N. Buzgar, A. I. Apopei, A. Buzatu, J. of Archaeological Science. 2013, 40(4), 2128–2135.
[2] T. Gatta, L. Campanella, C. Coluzza, V. Mambro, P. Postorino, M. Tomassetti, G. Visco. Chemistry Central
J. 2012, 6 Suppl 2(2), S2.
[3] E. P. Tomasini, G. Siracusano, M. S. Maier, Microchemical J. 2012, 102, 28–37.
[4] Butterworth-Heinemann (ed.), Pigment Compendium: A Dictionary of Historical Pigments, Elsevier
Butterworth-Heinemann: Burlington, Massachussets, 2005.
[5] E. P. Tomasini, E. B. Halac, M. Reinoso, E. J. Di Liscia, M. S. Maier, J. of Raman Spectrosc. 2012, 43(11),
1671–1675.
[6] O. Beyssac, B. Goffé, J.-P- Petitet, E. Froigneux, M. Moreau, J.-N. Rouzaud, Spectrochimica Acta Part A.
2003, 59(10), 2267–2276.
[7] J. Jehlička, O. Urban, J. Pokorný, Spectrochimica Acta Part A. 2003, 59(10), 2341–2352.
[8] M. Bouchard, D. C. Smith, Spectrochimica Acta Part A. 2003, 59(10), 2247–2266.
[9] A. Samokhvalov, Y. Liu, J. D. Simon, Photochemistry and Photobiology. 2007, 80(1), 84–88.
[10]S. A. Centeno, J. Shamir, J. of Molecular Structure. 2008, 873 (1-3), 149–159.
59
Book of Abstracts
P15
Raman Spectroscopy and SEM-EDS Studies Revealing Treatment
History and Pigments of the Government Palace Tower Clock in
Helsinki Empire Senate Square
Kepa Castro,1* Maite Maguregui,1 Silvia Fdez- Ortiz de Vallejuelo,1 Raili Laakso,2
Ulla Knuutinen,3 Juan Manuel Madariaga1
Department of Analytical Chemistry, University of the Basque Country (UPV/EHU), Bilbao, Spain,
2
Helsinki Metropolia University of Applied Sciences, Finland
3
Department of Art and Culture Studies, University of Jyväskylä, Finland
1
Combined restoration and material research of the tower clock of the Government Palace (originally
the Senate) in Helsinki has been a remarkable cultural heritage project. The Government Palace is a
typical Empire palace in Empire center of Helsinki, where buildings around the Senate Square are
internationally significant example of the neoclassical style. The German-born architect Carl Ludwig
Engel (1778-1840) designed The Government Palace, the Cathedral, the main building of the University
of Helsinki and the Helsinki University Library. The first building to be completed in 1822 was the
Senate. The tower clock of the Senate is Finnish origin and made by the famous watchmaker family
Könni. The clock has two faces: one towards the Senate Square and the other facing the courtyard. The
clock faces are nearly 1,5 meters in diameter. Architect Engel had drawn detailed instructions for the
machinery of the clocks at the desired characteristics.
Worn parts of the machinery of this 190 years old clock have been replaced as needed over the decade
and the plates have been in their original place until 2010. The colour of the clock faces has been
altered several times. Under the light blue coating there were found several other color layers. For the
restoration, it was needed to identify the first black layer, because the clock was decided to restore with
its original color. The other paint layers were important, because they provided information and dating
about treatment history and pigments used in Finland after 1822. In the 19th century a wide range of
new industrial pigments were replacing old traditional pigments in Europe. However, there are only
few case studies about the use of these new pigments in Finland.[1]
Material research of the clock faces was prepared in two steps. First, preliminary elemental analyses
with portable, non-invasive InnovX, EDXRF were carried out and microphotographs from paint layers
cross-sections were also acquired. Then, the studies continued with Raman and SEM-EDS. Raman
analyses were carried out by means of inVia Renishaw confocal microRaman spectrometer coupled
to a DMLM Leica microscope provided with 5x, 20x, 50x, 50x (long distance) and 100x lenses using a
514 and a 785 nm excitation lasers. Lasers were set at low power (not more than 1mW at the sample)
in order to avoid thermal photodecomposition. Spectra were acquired between 150 and 3200 cm-1 (1
cm-1 spectral resolution) and several scans were accumulated for each spectrum in order to improve the
signal-to-noise ratio. In order to obtain Raman chemical images, StreamLine technology was employed.
The inVia’s motorised microscope stage moves the sample beneath the lens so that the line is rastered
across the region of interest. Data are swept synchronously across the detector as the line moves across
the sample, and are read out continuously. The spectral imaging was carried out with the 514nm laser
and 785nm laser. The quality of measurements was assured by means of an internal calibration and
a diary calibration with a silicon chip. The collected Raman spectra were compared with standard
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spectra databases [2] and databases available online such as RRUFF.[3] When necessary, single Raman
spectra were also acquired. In addition, SEM-EDS measurements were carried out to determine the
elemental distribution images in the cross-section of the samples. The measurements were performed
using an EVO40 scanning electron microscope (Carl Zeiss) coupled to an X-Max energy-dispersive
X-ray spectrometer (Oxford Instruments). EDS analysis was carried out using a working distance of
8-10 mm, an I Probe of 180 pA, an acceleration potential of 30 kV and 10 scans.
The samples from the clock were analysed as cross-sections in order to identify all restorations that had
taken place all along the life of the clock, as well as to determine what its original colour was. Thanks
to the analytical methodology carried out, it was possible to determine the presence of the pigments
in the different layers of the cross-sections. The original colour seems to be black, that, as time went
by, was covered by a red layer, then by a grey layer, then by a blue layer, then by a yellow layer and
finally by a blue layer. Pigments such as red lead, hematite, Prussian blue, zinc chromate, massicot,
phthalocyanine blue, rutile and carbon black were determined in the different layers. Raman analyses
were corroborated by the chemical images provided by SEM-EDS analysis carried out with the same
cross-section samples.
Figure 1. Raman spectra of two layer from cross-section; Ma
(masssicot), ZY (zinc chromate), PR (Prussian blue) and PH
(phthalocyanine blue)
Acknowledgements
This work has been partially supported by Global Change and Heritage project (UFI11/26) funded by
the University of the Basque Country (UPV/EHU). The authors are grateful for technical and human
support provided by the Raman-LASPEA Laboratory of the SGIker (UPV/EHU, MICINN, GV/EJ,
ERDF and ESF).
References
[1] K. Castro, U. Knuutinen, S. Fdez-Ortiz de Vallejuelo, M. Irazola, J. M. Madariaga, Spectrochimica Acta
Part A. 2013, 106, 104–109.
[2] K. Castro, M. Pérez-Alonso, M. D. Rodríguez-Laso, L. A. Fernández, J. M. Madariaga, Analytical and
Bioanalytical Chemistry. 2005, 382, 248.
[3] R. T. Downs, Program and Abstracts of the 19th General Meeting of the International Mineralogical
Association in Kobe, Japan, 2006, O03–13.
61
Book of Abstracts
P16
Feasibility Study of Portable Raman Spectroscopy for
Characterization of Ground Material of Easel Paintings
(Case Study: Sradar As’ad-e Bakhtiary Painting of Kamal-al Molk)
Mohsen Ghanooni,1*, Hamid Motahari,2 Rasoul Malekfar,2 Ehsan Talebian2
Department of conservation, Parliament Library & Museum of Iran, Tehran,
2
Department of Physics, Tarbiat Modares University, Iran, Tehran
1
One of the most important approaches for conservators is the exact characterization of art work
components. This is important especially for conservation of paintings. Also analysis methods are
useful for identification of ground and paint layer components in treatment process. These analysis
methods can be divided to nondestructive and destructive methods. However, the first one is far better
than the second one for conservators. In order to study the nondestructive methods for conservation
of paintings, we have tried to investigate the feasibility study of using a portable nondestructive
characterization system. This feasibility study has been used for characterization of painting ground
by means of portable back-scattering micro-Raman spectroscopy. The obtained results have been
compared with the data obtained from another main systems, Almega Thermo Nicolet Raman
scattering spectrometer and FT-IR spectroscopy. Our primary question that is: “Can we rely on the
portable Raman data for characterization of the painting ground? Fir this purposes we have analyzed
the »Sradar As’ad-e Bakhtiary painting« which was composed by Kamal-al Molk. Kamal-al Molk was
the well-known painter of the 19th and 20th centuries of Iran. This tool shows a reliable result but in
such cases, we can check the data with a second method such as FT-IR spectroscopy. The recorded
spectra from the portable Raman spectrometer shows high agreement when compared with the FTIR
spectroscopy results. In addition some difficulties appear, i. e. some ambiguity, from qualitative and
quantitative point of view, in analyzing the recorded spectra can arise. However, these can be resolved
by using other techniques especially for calibration purposes of the used tools. It is obvious from Figs. 1
of the recorded Raman spectra that a series of peaks observed from 890 cm-1 to 1800 cm-1 as the main
fingerprint bases of the origin of the materials used in the painting These peaks are related to Arabic
Figure 1. The Raman spectra of Sample No RP15
belong to ground materials of Sardar As'ad Painting
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gum and Bees wax and Gelatin. Also there are some other peaks in the range around 2700 to 3000
cm-1in full spectra that are evidence for using of egg white and yolk in this painting.
Finally, from these evaluations we obtain that the portable Raman instrument results are so useful
for getting information within superior historical paintings as a main nondestructive test and without
any damaging on it. Also the results are consistent with the recorded FTIR spectroscopy results
which is located at the laboratory whereas Raman portable system can be carried out to the situation
of the painting. The final consistency and agreement between the data obtained from the portable
Raman and the FTIR spectrometers appear that the recorded data are completely convincing but the
Raman portable system is very simple and can be applied for every painting and regardless of its place.
Therefore we can claim that the Raman portable system can be considered as the ideal tool for the
analysis purposes of historical paintings.
References
[1] K. Castro, M. D. Rodrigues-Laso, L. A. Fernandez, Madariaga, J. Raman Spectros. 2001, 33, 17–25.
[2] L. Burgio, R. J. H. Clark, Spectrochim. Acta Part A. 2001, 57, 1491–1521.
[3] Z. E. Papliaka, K. S. Andrikopoulos, E. A. Varella, J. of Cultural heritage. 2010, 11, 381–391.
[4] A. Duran, M. L. Franquelo, M. A. Centeno, T. Espejoc, J. L. Perez-Rodriguez, J. Raman Spectrosc. 2011,
42, 48–55.
[5] T. Aguayo, E. Clavijo, F. Eisner, C. Ossa-Izquierdo, M. M. Campos-Vallette, J. Raman Spectrosc. 2011, 42
2143–2148.
[6] G. Simsek, Ph. Colomban, V. Milande, J. Raman Spectrosc. 41 (2010) 529–536.
[7] T. R. Ravindran, A. K. Arora, S. Ramya, R. V. Subba Raob, B. Raj, J. Raman Spectrosc. 2011, 42, 803–807.
[8] C. Miguel, A. Claro, A. P. Goncalves, V. S. F. Muralha, M. J. Melo, J. Raman Spectrosc. 2009, 40, 1966–
1973.
63
Book of Abstracts
P17
The Sibyls from the church of San Pedro Telmo: a spectroscopic
investigation
Marta S. Maier,1* Fernando Marte,2 Valeria P. Careaga,1 Dalva L. A. de Faria3
UMYMFOR - Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales,
Universidad de
Buenos Aires, CABA, Argentina, [email protected], [email protected]
2
CEIRCAB-Tarea, Universidad Nacional de San Martín, CABA, Argentina, [email protected]
3
Instituto de Química, Universidade de São Paulo, Butantã, São Paulo, SP, Brazil,
1
The series of the Sibyls from the church of San Pedro Telmo in Buenos Aires is one of the most important groups of paintings of argentine colonial art.[1] These twelve paintings depict the Sibyls prophesying on episodes of the life of Christ (Figure 1). Ten of them were performed in the 18th century while
those correspond ing to the Delphic and Tiburtine Sibyls were painted in 1864 during the first restoration of the series in order to replace the originals due to their poor state of conservation.
Figure 1. Sibyl Samia, 18th century (left) and Delphic Sibyl (1864) (right)
There are two attributions regarding the origin of these paintings, one points to a Spanish origin while
the other one suggests that they were painted in a workshop of the Cuzco region. During a restoration of
the series in 2005 several microsamples were extracted from original and repainted areas of the twelve
paintings and analyzed by Raman microscopy and scanning electron microscopy coupled with energy
dispersive X-ray spectroscopy (SEM/EDS). High performance liquid chromatography (HPLC) was applied to confirm the presence of organic pigments. The aim of our work was to establish if there were
differences in the color palette of the 18th and 19th centuries Sibyls and if it was possible to contribute
to the elucidation of the origin of the series based on the materiality of the paintings.
Light microscopy examination of the cross-sections of the samples revealed a thin pigment layer and
a grayish preparation layer. In those samples taken from repainted areas, two pigment layers were observed. Raman microscopy revealed the presence of vermilion in the intense red areas as well as mixed
with basic lead carbonate in the carnations. Lazurite (main bands at 546 and 1091 cm-1) was identified
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in a green sample taken from a repainted area in admixture with a yellow component, presumably an
organic colorant. The blue pigments were identified as indigo in the 18th century Sibyls and Prussian
blue in the Delphic and Tiburtine Sibyls. Both blue pigments have been used in Europe and in South
American colonial art in the XVIII century.[2] The faded red lake from the Samia robe was identified
as alizarin. This is the main anthraquinone colorant of madder, which comes from the roots of Rubia
tinctorum.[3] Identification of this pigment suggests a Spanish origin of the series in accordance with
historical data. Although red lakes have been used in colonial South American art, only carmine, the
red lake obtained from cochineal has been identified in paintings from the Andean region.[4]
Acknowledgements
This work has been financially supported by the National Research Council of Argentina (CONICET),
the University of Buenos Aires, and the National Scientific Agency of Argentina (ANPCyT).
References
[1] A. Rodríguez Romero, J. E. Burucúas, Las 12 Sibilas de la Parroquia San Pedro G. Telmo. Un trabajo de
conservación y de crítica histórica, UNSAM: Buenos Aires, 2005, p. 26.
[2] A. Seldes, L. E. Burucúa, M. S. Maier, G. Abad, A. Jáuregui, G. Siracusano, J. A. I. C. S. 1999, 38, 100.
[3] H. Schweppe, J. Winter, Artists’ Pigments. A handbook of their History and Characteristics, vol. 3, National Gallery of Art: Washington, 1997, p. 109.
[4] A. Seldes, J. E. Burucúa, G. Siracusano, M.S. Maier, G. Abad, J. A. I. C. S. 2002, 42, 225.
65
Book of Abstracts
P18
Pigment identification of illuminated medieval manuscripts by
means of a new, portable Raman equipment
Debbie Lauwers,1* Vincent Cattersel,2 Annabel Van Eester,2
Ine Craenhals,2 Jitske Van Groenland,2 Luc Moens,1 Peter Vandenabeele3
Department of Analytical Chemistry, Research Group Raman Spectroscopy, Ghent University, Belgium,
+32 (0)9 264 47 19, [email protected], [email protected]
2
Artesis university College of Antwerp, Belgium, [email protected]
3
Department of Archaeology, Archaeometry research group, Ghent University, Belgium,
+32 (0)9 264 47 17, +32 (0)9 331 01 66, [email protected]
1
Direct identification of pigments in medieval illuminated manuscripts was one of the first applications of
Raman spectroscopy in art and archaeology.[1] In previous in-situ analysis of handwritings the equipment
was typically provided with only one excitation source.[2-4] In this work a new mobile Raman spectrometer,
EZRAMAN-I-DUAL Raman system (Enwave Optonics, Irvine CA, USA) is introduced to characterise the
pigments used in different medieval manuscripts from the library in Bruges (Civitate Dei (Ms.106), Chronicles
of Flanders (Ms.437), Cistercian manuscripts (Ms.27, 35, 140 and 142)). This Raman spectrometer has the
advantage to interchange between two laser wavelengths (785nm and 532nm).
The investigated manuscripts originate from the collection of the abbey ‘Ten Duinen’ (Koksijde, Belgium) and
are preserved in the city library of heritage in Bruges, Biekorf. Civitate Dei (Ms.106) was written during the
second half of the 15th century by Aurelius Augustine (~ St Augustine) and consists of 22 parts with a total of
262 folios. On folio 22r a miniature, attributed to Willem Vrelant, a decorated initial, a fleuronnée initial, and
a colourful frame were examined.[5] Chronicles of Flanders (Ms. 437, 15th century) was written by Antonius
the Roovere, one of the famous authors during the 15th century. Research focussed on illuminations on the
historical events during the reign of Mary of Burgundy (e.g. The accolade of Maximilian of Austria during
the chapter of ‘the Golden Fleece’ in Bruges in 1478).[6] The third series of manuscripts that were examined,
were Cistercian manuscripts (Ms. 27, 35, 140 and 142). These four manuscripts date from the 12th century
and are probably produced in their own scriptorium.[7] Despite their sober illumination, interesting green,
blue and red areas were characterised .
As mentioned, the Raman analysis was performed by a new mobile instrument, EZRAMAN-I-DUAL
Raman system. The fiber-optic-based device is equipped with two type of lasers, a red diode laser (785
nm) and a green Nd:YAG laser (532 nm) and has three interchangeable lenses: a standard lens (STD), a
long working distance lens (LWD) and a high numerical aperture lens (HiNA). The Raman spectrometer
also consist of an adjustable power controller for each laser and a CCD detection system. When comparing
this instrument to other portable spectrometers, several practical advantages can be observed. Besides the
advantage that one can interchange between the lasers, the instrument can work both on battery (live time
of 6h 30min) or external power supply. This increases the on-site working possibilities.
When performing direct analysis, good quality positioning (i.e. focussing) of the equipment is of utmost
importance to obtain high quality results.[8] It is required to have a stable equipment and the way the
instrument is mounted must be save. Apart from the requirement for stable positioning equipment,
it should also allow for easy macro and micro-positioning. Figure 1 represents the set-up used for correct
positioning of the instrument for direct Raman analysis of the manuscripts, by means of an articulating
arm.
By using this approach different pigments were examined. In spite of a strong fluorescence background,
some preliminary results could be made: pigments such as lead white (2PbCO3·Pb(OH)2), lead–tin yellow
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type I (Pb2SnO4), massicot (PbO), vermilion (HgS), red lead (Pb3O4) and azurite Cu3(CO3)2(OH)2 could be
identified. These pigments were often used in medieval artworks,objects which indicate the authenticity of
the manuscripts.
Conclusion. It can be concluded that the new mobile Raman spectrometer, EZRAMAN-I-DUAL Raman
system, is a very good device for the identification of pigments. The investigation of the medieval manuscripts
(Civitate Dei, Chronicles of Flanders, Cistercian manuscripts) results in the identification of , amongst
others, lead white (2PbCO3·Pb(OH)2), lea-tin yellow type I (Pb2SnO4), massicot (PbO), vermilion (HgS), red
lead (Pb3O4) and azurite (Cu3(CO3)2(OH )2), – which is in agreement with the medieval artists’ palette.
Figure 1. Image of the way of positioning the spectrometer a.); Overview of the total set-up b.).
Acknowledgements
We would like to thank the library of Heritage, more specifically Dr. Ludo Vandamme for the disposal of
the medieval manuscripts. The research is financially supported by the European Commission, through the
FP-7 MEMORI project ‘Measurement, Effect Assessment and Mitigation of Pollutant Impact on Movable
Cultural Assets. Innovative Research for Market Transfer‘ (http://www.memori-project.eu/memori.html).
References
[1] P. Dhamelincourt, P. Bisson, Microsc. Acta. 1977, 79, 267–276.
[2] A. Deneckere, M. Leeflang, M. Bloem, C. A. Chavannes-Mazel, B. Vekemans, L. Vincze, P. Vandenabeele, L.
Moens, Spectrochimica Acta Part A. 2011, 83, 194–199.
[3] D. Bersani, P. Lottici, F. Vignali G. Zanichelli, J. Raman Spectrosc. 2006, 37, 1012–1018.
[4] P. Vitek, E. Ali, H.G.M. Edwards, J. Jehlicka, R. Cox, K. Page, Spectrochimica Acta Part A, 2012, 86, 320-327.
[5] R. Vercruysse, Drie Vlaamse Cisterciënzer abdijen en hun bibliotheken, OKV: Belgium, 2002; 2.
[6] J. Oosterman. Tijdschrift voor Nederlandse Taal en Letterkunde, 2002, 118, 22–37.
[7] W. Le Loup, Vlaamse kunst op perkament: handschriften en miniaturen te Brugge van de 12de tot de 16de
eeuw, Brugge: Stadsbestuur, 1981, 81–82.
[8] P. Vandenabeele, K. Castro, M. Hargraeves, L. Moens, J.M. Madariaga, H. G. M. Edwards, Analytica Chimica
Acta. 2007, 588, 108–116.
67
Book of Abstracts
P19
Micro-Raman identification of pigments on wall paintings:
characterisation of Langus and Sternen’s palettes
Petra Bešlagić,1* Martina Lesar Kikelj1
1
Restoration Centre, Conservation Centre, Institute for the Protection of the Cultural Heritage of
Slovenia, Slovenia, +386 1 2343 120, [email protected]
The conservation and restoration of wall paintings in six side chapels in Franciscan Church of the
Annunciation, Ljubljana, Slovenia were carried out between 2006 and 2012.
Paintings were painted in fresco and secco techniques between 1845 and 1855 by Matevž Langus (17921855), who was in his time one of the most esteemed Slovenian painter. A few decades later, in 1882
Janez Wolf partly preserved, and in some places overpainted or newly painted one of the chapels, St.
Francis chapel. After the earthquake in 1895 all chapels were partly restored by two Viennese painters,
Klainert and Kastner. A large number of restoration works in the past changed the appearance to
such an extent that in some places the original image area and plaster were gone. Because of that, the
biggest intervention in the chapels was carried out in between 1925 and 1933 by Matej Sternen (18701949), impressionist painter and restorer, who applied new plaster and paint layers. Sternen also newly
painted the vaulted nave and presbytery between 1935 and 1936.[1,2]
In 2006 wall paintings in the chapels were severely deteriorated due to poor technology and quality
of plaster, pollution of the urban environment, the problems of moisture, salt crystallization and
inappropriate choice of consolidants in past restoration interventions.
During the restoration process of some areas of the painting, it was not completely clear which areas
of paintings are the work of Langus or Sternen. Because of that, the aim of our work was to identify
pigments that those two painters used for the execution of wall paintings.
Samples taken from chapels were analysed and pigments were identified. We also analysed several
samples of paint layers taken from Sternen’s painting of vaulted presbytery ceiling in Franciscan
Church of the Annunciation for the characterization of his palette. For the characterisation of Langus’s
palette we analysed paint samples taken from painted vault of large dome in Church of the Mother of
God, Šmarna gora, Ljubljana.
Samples of paint layers were taken from different colour areas of paintings and prepared as crosssections, having been embedded in polyester resin and polished. Cross-sections were examined by
using optical microscope as well as micro-Raman spectrometer. Raman spectra of paint layers were
obtained by using 633 and 785 nm laser excitation line with a Horiba Jobin Yvonne LabRAM HR800
Raman spectrometer equipped with Olympus BXFM optical microscope, a grating with 600 grooves
per mm and an air-cooled CCD detector. Some of the samples were also analysed with SEM/EDS and
micro-FTIR.
The results showed that Langus and Sternen palettes are very similar: differences may be found in
the green and red pigments. Size of used pigments and also combination of pigments was different in
Langus and Sternen’s palettes. Samples taken from the chapels were evaluated and in some cases, but
not in all (because of the similarities in their palettes), we could determine if paint layer was work of
Langus or Sternen’s.
The present micro-Raman study of pigments used by Langus and Sternen provide important information
on used pigments and their palettes. Results can be used for future conservation and restoration
purposes and also as a help for future investigations on Langus and Sternen’s wall paintings.
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References [1] F. Stele, Kronika slovenskih mest. 1935, 2(3), 221–226.
[2] J. Dostal, Dom in svet. 1937/1938, 50(7), 332–338.
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New Methods in Raman Spectroscopy – Combining Other Microscopes for mineral and pigment analysis
Josef Sedlmeier,1* Alan Brooker,2 Kenneth Williams3
Renishaw s.r.o., Brno, Czech Repubblic, +420 548 428 725, [email protected]
Renishaw Plc., Glos, United Kingdom, +44 0 1453 524 524, [email protected]
3
Renishaw Plc., Glos, United Kingdom, +44 0 1453 524 524, [email protected]
1
2
Introduction. The advantages of using an optical microscope coupled to a Raman spectrometer have
been well documented over the last three decades. The advances in filter technology made it possible to
develop the “bench top” Raman microscope systems that have dominated the market place for the last
ten years. The ease of use which has accompanied these advances in instrumentation has led to a rapid
expansion in the use of the Raman technology over many diverse fields, such as materials research,
chemical catalysis, biochemical and biomedical, through to art restoration and gemmology. Given the
level of interest and the diversity of applications, new demands are now being made by researchers to
move away from using traditional optical microscopy to visualise their samples. The purpose of this
presentation is to detail the very recent advances that have been made in combining a variety of alternative microscopes to identify the sample area of interest on which a Raman analysis can be performed. We have been working with Smiths Industries to combine the Renishaw Raman microscope with
their infrared (FT-IR) system, to produce a combined Raman/infrared microscope capable of integrated vibrational analysis. In addition we have worked with a selection of scanning electron microscope
manufacturers to provide Raman analysis from materials inside the SEM.
Results and Discussions
The combined analysis by Raman and infrared spectroscopes offers a real benefit for “same spot” investigation, together with the obvious advantages of acquiring a complete vibrational picture of the
sample. The technology employed is relatively simple but utilises a conventional Raman microscope
which can allow an infrared beam to pass down unobstructed to the sample. The objective lens used is
a diamond AFR cell, the diamond of which is transparent to the incident Raman laser beam.
The SEM structural and chemical analyser (SEM-SCA) combines both SEM and Raman techniques
into one system, so that users can take full advantage of the high spatial resolution afforded by the
SEM, and the chemical information revealed by Raman. This unique combination enables SEM manufacturers to supply a SEM-Raman system that enables the spectrometer to »see« the same area as the
SEM - a micrometer-scale laser spot is projected onto the surface of a sample visible in the SEM image.
The SEM-SCA hardware can be fitted to most SEMs without compromising the SEM performance in
any way. The nature of Raman spectroscopy means that its performance is unaffected by the SEM environment - high vacuum (HV), low vacuum (LV), environmental (ESEM), and high or low (cryogenic)
temperatures. The advantages of this method are from the SEM view that SEM overcomes the limitations of optical microscopy with respect to: (a) depth of field - the SEM retains good depth of field even at
high magnifications. (b) contrast - SEM contrast mechanisms can easily distinguish optically identical
or similar materials. (c) spatial resolution - SEM spatial resolution is typically 3-4 orders of magnitude
better than optical microscopy.
Raman spectroscopy meets unfulfilled SEM/EDS analytical requirements: (a) EDS yields elemental
information only whilst Raman provides structural, chemical, and physical information. (b) EDS is
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poor for analysing light elements whilst Raman is sensitive to light element chemistry.
The instrument can also perform photoluminescence (PL) and cathodoluminescence (CL) studies as
the SEM-SCA collection optics are fully compatible with both PL and CL spectroscopes. The former
uses a laser as the excitation source, the latter the electron beam. Each technique can reveal both electronic and physical information about the sample, with CL being sensitive to very subtle changes in
composition and residual strain.
Examples will be presented from topical areas including pigment and minerals analysis and forensic
science applications.
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Horiba Jobin Yvon advances in Raman instrumentation: explore
new boundaries in art and archaeology
Romain Bruder1*
1
HORIBA Scientific, Research Division, HORIBA Jobin Yvon S. A. S., Palaiseau – France,
[email protected]
Horiba Jobin Yvon is a world leader in Raman spectroscopy. As such, Horiba Jobin Yvon continuously
innovates to meet evolving requirements in the different application fields of Raman spectroscopy.
This presentation aims at introducing the latest developments carried out by Horiba Jobin Yvon in
terms of Raman microscopes and instrumentation.
From analytical instruments, with the new XploRA ONE microscope, rugged and designed for microRaman routine analysis, towards high-end systems such as the new LabRam HR Evolution, Horiba
Jobin Yvon proposes a range of micro-Raman spectrometers well suited to the needs of art and
archaeology studies. May it be to simply identify pigments or to study in depth corrosion mechanisms
and products, newly designed options and accessories, enabling fast mapping, database identification
or transmission Raman, bring valuable information to cultural heritage specialists.
Figure 1. XploRA OneTM –
Figure 2. LabRam HR EvolutionTM – Horiba Jobin Yvon
Horiba Jobin Yvon
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OP10
A portable 1064 nm Raman spectrometer for analysis of cultural
heritage items
Alessandro Crivelli,1* Maurizio Aceto,2 Pietro Baraldi,2 Maurizio Bruni,1
Angelo Agostino,4 Gaia Fenoglio4
Nordtest s.r.l., Italy, +39 0143 62422, [email protected].
Dipartimento di Scienze e Innovazione Tecnologica (DISIT), Università degli Studi del Piemonte
Orientale, Italy; Centro Interdisciplinare per lo Studio e la Conservazione dei Beni Culturali
(CenISCo), Università degli Studi del Piemonte Orientale, Italy
3
Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia,
Modena, Italy
4
Dipartimento di Chimica, Università degli Studi di Torino, Torino, Italy; Nanostructured Interfaces
and Surfaces Center of Excellence (NIS), Torino, Italy
1
2
The most common drawback when performing Raman analysis is the occurrence of fluorescence
emission in the spectra. In several cases, fluorescence is so high that the spectral features of the
compounds of interest can hardly, if ever, be identified. Since fluorescence emission is proportional
to the energy of the laser source, this phenomenon is particularly effective when UV-visible laser
sources are used, such as 244, 488, 514, 532 or 633 nm. NIR sources such as 785 nm lasers are suitable
to address this drawback, but an even more suitable solution is that yielded by the availability of a
1064 nm laser source. Raman analysis of several organic substances gives no results when UV-visible
sources are used, while it can result in high quality spectra when a 1064 nm source is used. This is a
characteristic behaviour of many organic materials of interest in the field of cultural heritage such as
parchment [1], paper [2], ivory [3], etc.
Figure 1. Raman spectra of a natural pearl a.) and of a garnet b.) on
an XI century manuscript binding from Italy.
1064 nm laser sources are typically used on Fourier Transform Raman spectrometers, usually
equipped with liquid nitrogen-cooled detectors. This makes very difficult to design portable Raman
systems allowing to perform in situ analysis with 1064 nm source. Only recently instruments equipped
with Thermoelectrically cooled detectors have been made available, allowing to reduce the overall
dimensions of the systems.
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The Rigaku XantusTM-1064 Handheld Raman Analyzer is a very compact Raman spectrometer,
equipped with a 500 mW laser and a Peltier-cooled high sensitivity array. The spectral resolution is 10
cm-1 calculated as Full Width at Half Maximum (FWHM), while the spectral range is 200-2200 cm-1.
It can work with a rechargeable Li ion battery (up to 4 working hours per charge) and its weight is 2.3
kg. All these features make XantusTM-1064 spectrometer highly suitable for in situ measurements, with
particular reference to analysis of cultural heritage items which cannot be sampled nor moved outside
their natural locations, i.e. museums, libraries, churches or other cultural institutions.
Some applications of Raman analysis with XantusTM-1064 spectrometer on artworks will be illustrated
in this presentation. Particular concern will be given to gemological analysis (identification of different
gemstones, see an example in Figure 1), to analysis of materials of organic or partially organic nature
such as parchment or ivory and to analysis of painted artworks such as illuminated manuscripts.
Acknowledgements
This work has been financially supported by Nordtest s.r.l.
References
[1] H. G. M. Edwards, D. W. Farwell, E. M. Newton, F. Rull Perez, S. Jorge Villar, Spectrochimica Acta A. 2001,
57, 1223.
[2] H. G. M. Edwards, D. W. Farwell, D. Webster, Spectrochim. Acta A. 1997, 53, 2383.
[3] H. G. M. Edwards, D, W. Farwell, Spectrochimica Acta A. 1995, 51, 2073.
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Novel 1064 nm Dispersive Raman Spectrometer and Raman Microscope for Non-invasive Pigment Analysis
Lin Chandler,1*Jack Qian,1 Owen Wu,1 Daniel Thomas2
1
2
BaySpec, Inc., San Jose, USA, +1 (408)512-5928, [email protected]
Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian
Institution, Washington, DC, USA
Identifying pigments in both art and archeological samples often demands a versatile analytical technique with high specificity and high accuracy, the capacity for direct measurement without sample contact or destruction, and minimal need for sample preparation[1,2]. Raman spectroscopy proves to be by
far the most suitable analytical tool that can satisfy these essential criteria, and has proven useful for
identifying falsification in, and monitoring the repair of, ancient artwork. Coupled with a microscope,
Raman spectrosopy is capable of identifying trace forensic evidence at micron scales [3].
With recent advances in diode lasers and fast array detectors, Raman spectroscopy has improved dramatically with regards to ease of operation and analysis time, all at steadily lowering costs. These
advances have led to widespread use in many fields, including material identification, process control,
nanomaterial research and biological sciences. However, high fluorescence backgrounds encountered
in colorful samples have limited the use of Raman spectroscopy in pigment analysis. FT-Raman has
been the traditional solution for suppressing fluorescent interferences; however, FT-Raman is relatively cumbersome with constant moving parts and long acquisition times. This paper will introduce
a new class of 1064 nm dispersive Raman spectrometer with a highly efficient patented VPG grating,
fast optics, and a deep-cooled InGaAs detector. The unique three wavelength confocal Raman microscope (532, 785 1064 nm) will be highlighted. Without any moving parts, these compact 1064 Raman
spectrometers feature high sensitivity, high spectral resolution, and stability. The built-in battery, remote control via WiFi, and flexible fiber probe accessories make this instrument extremely suitable for
field applications. Ultimately, the 1064 Dispersive Raman is the solution for the most complex pigment
analysis, and is particularly useful for samples that fluoresce under visible light excitation. This paper
Figure 1. Comparison of 785nm (left) and 1064nm (right) Raman spectra of oil paints in
different colors. Superior flurescence avoidence at 1064nm enhanced the Raman features. The
spectra were taken by BaySpec’s NomadicTM multi-excitation Raman microscope.
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will present experimental results obtained from archaeological materials, such as brightly pigmented
feathers, and will demonstrate the utility of 1064 nm Raman spectra for material identification.
Acknowledgements
DBT is funded by a Peter Buck postdoctoral fellowship from the National Museum of Natural History,
Smithsonian Institution.
References
[1] P. Vandenabeele, H.G.M. Edwards, L. Moens, Chem Rev. 2007, 107(3), 675–686.
[2] A. M. Correia, R. J. H. Clark, M. I. M. Ribeir, M. L. R. Duate, J. Raman Spectrosc. 2007, 38(11), 1390–1405.
[3] G. D. Smith, R. J. H. Clark, Studies in Conservation. 2001, supplement 1, 92–106.
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PL2
Surface-enhanced Raman spectroscopy in Art and Archaeology
Marco Leona1*
1
Department of Scientific Research, The Metropolitan Museum of Art, New York, USA,
1-212-396-5476, [email protected]
Surface-enhanced Raman scattering (SERS) has been the subject of considerable study and substantial
application in the field of cultural heritage analysis in the last ten years. The giant enhancement of
Raman scattering at atomically rough silver surfaces was first observed – but not recognized as such –
in 19741. The surface-enhanced Raman scattering effect was recognized in 1977 [2,3] and ten years after,
the technique found its first application in the cultural heritage field4. It took another fifteen years,
the introduction of CCD equipped Raman microscopes, and a switch to silver colloids, for SERS to be
used again in the analysis of materials of archaeological and artistic interest [5-7], this time with a lasting
impact. It could be argued that with the exception of immuno-SERS biomedical assays, the analysis of
organic colorants and dyes in cultural heritage material is the principal practical application of SERS
today.
Figure 1. Objects investigated with SERS at the Metropolitan Museum
of Art: among them archaeological and medieval polychrome sculpture,
textiles, drawings and paintings.
Several groups are currently active in SERS research on cultural heritage, and considerable progress
has been made in the study of natural dyes, in the development of plasmonic substrates and analytical
protocols, and in the application of SERS to actual samples from works of art. A number of misconceived
notions have however slowed down the diffusion of SERS: chief among them are the supposed lack
of reproducibility of the technique, the difficulty in preparing reliable and stable supports, and the
perceived difficulty in searching SERS spectra against a library.
While dyes differ widely in their SERS efficiency (a term used here to include both differences in SERS
cross-section and the affinity of a dye for a given plasmonic substrate), thus complicating quantitative
estimations of dyestuff components and sometimes making it impossible to detect the target analyte
over matrix interferences, it can be shown that SERS is otherwise reliable and reproducible, and that
SERS spectra can easily be compared with appropriate library references.
At the Metropolitan Museum of Art, SERS has been used to identify organic dyes in samples from over
one hundred works of art, ranging in dates from 2000 BC to the present. The range of dyes studied and
identified in works of art includes madder, kermes, lac, cochineal, methyl violet, nile blue and eosine,
from Ancient Egypt to the Impressionists and to Contemporary Art. In addition, almost all natural dyes
have been characterized by SERS, although some important classes, such as the flavonoids, remain
difficult to identify in micro-samples from ancient objects.
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While several plasmonic substrates and sample treatment approaches have been employed in the study
of dyes and colorants, we have found the use of resonant excitation, a stable and highly efficient silver
colloid [8], and a two-step measurement approach (analysis of the sample as-is, followed by recovery of
the sample and a second analysis after a lossless non-extractive hydrolysis sample treatment) [9] to give
the best results. Spectra thus obtained can be reliably compared with reference spectra, and searched
against a SERS spectral library containing over one hundred spectra representing different dyes
measured in different conditions, using the Correlation Coefficient approach or Principal Component
Analysis.
Microwave assisted reduction of silver sulfate in the presence of glucose and sodium citrate results in a
stable mono-disperse colloid. (Figure 2, left panel).
Figure 2. Left panel: optical absorption spectra of aliquots of the same Ag colloid,
sampled n days after synthesis. Right panel: a.) SERS spectrum of reference madder
lake upon HF treatment compared to those of a red glaze from Cézanne’s The card
players b.) on Ag microwave colloid upon HF treatment and c.) on 5x Ag microwave
colloid without hydrolysis. Marked with * are spurious bands due to the colloid.
Sample treatment prior to analysis adds versatility to SERS. HF vapor hydrolysis for textile and glaze
samples enhances sensitivity to the point where samples down to 20 µm can be analyzed. EDTA/DMF
treatment coupled with gel mediated solid phase micro-extraction can be used for quasi non-invasive
analysis.
References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
M. P. Fleischmann, J. Hendra, A. J. McQuillan, Chem. Phys. Lett. 1974, 26, 163–166.
D. L. L. Jeanmaire, R. P. Van Duyne, J. Electroanal. Chem. Interfacial Electrochem. 1977, 84, 1–20.
M. G. Albrecht, J. A. Creighton, J. Am. Chem. Soc. 1977, 99, 5215–5217.
B. Guineau, V. Guichard, ICOM Committee for Conservation: 8th triennial meeting, Sydney, Australia,
6–11 September, 1987. Preprints, The Getty Conservation Institute: Marina del Rey, Sydney, Australia,
1987, 2, 659-666.
I. T. Shadi, B. Z. Chowdhry, M. J. Snowden, R. Withnall, J. Raman Spectrosc. 2004, 35, 800-807.
M. V. Cañamares, J. V. Garcia-Ramos, C. Domingo, S. Sanchez-Cortes, J. Raman Spectrosc. 2004, 35,
921–927.
M. Leona, 6th IRUG Meeting, Florence, March 29–April 1, 2004. Proceedings, Il Prato, Padova, 2005,
105–112.
M. Leona, PNAS. 2009, 106 (35), 14757.
F. Pozzi, J. R. Lombardi, S. Bruni, M. Leona, Anal. Chem. 2012, 84 (8), 3751.
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OP12
TLC-SERS of mauve, the first synthetic dye
Maria Vega Cañamares,1,3* David A. Reagan,2 Marco Leona3
Instituto de Estructura de la Materia, IEM-CSIC, Madrid, Spain,
2
Southern Connecticut State University, New Haven, Connecticut, [email protected]
3
Metropolitan Museum of Art, New York, +12123965476, [email protected]
1
Mauveine was the first synthetic organic dyestuff to be manufactured industrially. William Henry Perkin discovered this purple dye by chance when trying to synthesize quinine, the only known remedy for
malaria. He obtained a purple solution which he then used to colour silk. Up to then, most dyes were
natural compounds extracted from plants and animals. Perkin’s synthesis of mauve and the establishment of a factory to in 1862 to produce it commercially mark the beginnings of the modern dye industry.[1] The main components of mauveine are mauveine A and B; other components such as mauveine B2
and C were also discovered in 2007.[2]
In this study we endeavoured to synthesize mauveine and to obtain its Raman spectrum, using ordinary dispersive Raman spectroscopy, Fourier-Transfrom Raman, and Surface-enhanced Raman Scattering (SERS). These techniques are all well established for the analysis of artists’ pigments and dyes.[3]
In addition to measurements on the dye as synthesized we also attempted measurements on fractions
separated by Thin Layer Chroamtography (TLC).
The coupling of Thin Layer Chromatography (TLC) with Raman/SERS spectroscopy represents an interesting technique for the Raman analysis of mixtures. Coupling of TLC and SERS was first reported
by Henzel in 1977.[4] However, the use of this technique for the study of dyes is quite recent.[5,6] Here we
demonstrate its utility in the case of a highly fluorescent complex synthetic dye.
The synthesis of the dye was performed following Perkins’ original recipe as modified by Scaccia.[7] The
separation process was carried out by thin layer chromatography (TLC) utilizing a solution of isobutanol, acetic acid, and ethyl acetate. The samples were deposited onto a silica gel TLC plate and eluted in
a glass developing chamber. Dispersive Raman and SERS spectra were recorded in a Bruker Senterra
Raman spectrometer equipped with a long working distance microscope objective and a charge-coupled device detector. The 633 and 785 nm laser lines were employed to register the ordinary Raman
spectra. FT-Raman spectra were acquired with a Bruker RamII Vertex 70 spectrometer equipped with
a liquid nitrogen cooled Ge detector. The 1064-nm line provided by a Nd:YAG laser was used for excitation. Ag nanoparticles prepared by reduction with trisodium citrate[8] were used as SERS substrates.
Different aggregating agents were tested. For the TLC-SERS analysis, the samples were prepared by
placing a small amount of aggregated silver nanoparticles directly on the spot of separated each component.
No satisfactory ordinary Raman or FT-Raman spectra of mauve were obtained. This was due in the
case of ordinary dispersive Raman to the high fluorescence of the dye, and in the case of FT-Raman
to its high absorption of the Near IR radiation, leading to thermal damage before a spectrum could be
obtained. SERS however gave excellent spectra: the most intense SERS spectra were registered under
excitation at 633 nm and acidic conditions.
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Five different components of mauveine were separated by TLC: a light red spot at R f = 0.32 and four
purple spots at R f values of 0.56, 0.63, 0.70, and 0.78. No spectrum was obtained by direct Raman
analysis due to the low concentration of the dye in each analysed spot. On the contrary, intense SERS
spectra of each component were obtained. No interfering fluorescence was observed in the spectra of
the four purple spots (Figure 1). Band positions between the spectra only differed slightly from each
other, with only a few bands being unique for each component. Most bands also had similar intensities. The spectra for spots at R f = 0.70 and 0.78 were particularly related, both having, for instance, intense bands around 1017 cm-1. Spots at R f = 0.56 and 0.63 were also closely related, the bands around
1017 cm-1 being less intense than the corresponding bands in the other two spots.
To conclude, satisfactory Raman spectra of mauveine and its different components could be only
obtained by the application of SERS spectroscopy. The main difficulty in the analysis of mauve by
ordinary Raman spectroscopy was the intense fluorescent emission of the sample. By using SERS
however we were successful not only in recording a spectrum of the complex dye, but also in obtaining
spectra of each individual component of the dye mixture directly on a TLC plate.
Figure 1. SERS spectra of the four purple
compounds separated by TLC.
References
[1] P. Ball, Nature. 2006, 440, 429.
[2] J. S. De Melo, S. Takato, M. Sousa, M. J. Melo, A. J. Parola. Chemical Communications. 2007, 2624–2626.
[3] M. V. Cañamares, M. Leona, M. Bouchard, C. M. Grzywacz, J. Wouters, K. Trentelman, J. of Raman
Spectrosc. 2010, 41, 391–397.
[4] U. B. Henzel, C. Zeis, J. of Chromatography Library. 1977, 9, 147–188.
[5] C. L. Brosseau, A. Gambardella, F. Casadio, C. M. Grzywacz, J. Wouters, R. P. Van Duyne. Analytical
Chemistry. 2009, 81, 3056-3062.
[6] F. Pozzi, N. Shibayama, M. Leona, J. R. Lombardi. J. of Raman Spectrosc. 2013, 44, 102–107.
[7] R. L. Scaccia, D. Coughlin, D. W. Ball, J. of Chemical Education. 1998, 75, 769.
[8] P. C. Lee, D. Meisel, J. of Physical Chemistry. 1982, 86, 3391–3395.
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New photoreduced substrate for SERS analysis of organic colorants
Klara Retko,1* Polonca Ropret,1,2 Romana Cerc Korošec3
Research Institute, Conservation Centre, Institute for the Protection of Cultural Heritage of Slovenia,
Ljubljana, Slovenia, +38612343118, [email protected], [email protected]
2
Museum Conservation Institute, Smithsonian Institution, Suitland, Maryland, USA
3
University of Ljubljana, Faculty of Chemistry and Chemical Technology, Ljubljana, Slovenia,
1
In the last decades, the interest has emerged for the development of sensitive and selective techniques
that are effective for the detection of organic dyestuffs used as artists’ materials. One of the prospective
techniques is also Surface Enhanced Raman Spectroscopy (SERS), as it overcomes the weak Raman
activity of the organic pigments and dyes, in addition to fluorescence quenching.[1–3]
The signal enhancement depends strongly on the quality of the SERS-active substrate[4], with its
reproducibility being the main challenge of the technique. For that purpose, the described research
focused towards the synthesis of a stable and reproducible substrate of high viscosity. New UVphotoreduced substrate, using hydroxypropyl cellulose as the stabiliser and silver nitrate as the initial
substance, is suggested.
Substrates’ characteristics were examined by absorption spectroscopy (UV-Vis), electron microscopy
(FE-SEM) and Raman spectroscopy. It was established that the substrate stayed stable for several
months and that the aggregation of silver nanoparticles is induced spontaneously with no need of
adding any aggregation agent. Moreover, substrate alone shows a weak Raman activity, causing less
interference in spectra for further interpretation. The properties of the new substrate were compared
among some other known substrates and also tested with alizarin as a model substance (Figure 1). The
obtained Raman band positions of alizarin were in a good agreement with previously reported data.[5]
Figure 1. Comparison of a.) Raman spectrum and b.) SERS spectrum of alizarin. UV-photoreduced substrate was employed for
the SERS analysis, the bands typical of alizarin were determined. In the latter spectrum, the Raman signal is amplified above the
fluorescence signal.
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Furthermore, the substrate enabled the detection of organic colorants in colour layers. Although they
were prepared with different organic binders (also potential source of SERS signal), it was almost
exclusively the organic colorants which exhibited higher signal enhancements. It is possible to conclude,
that other organic components in binders have a weaker affinity to silver nanoparticles in the substrate,
thus producing insufficient signal for possible overlapping with the Raman bands of interest. It is worth
mentioning that no pre-treatment of the samples was needed prior to the analysis.
The research was extended to the examination of a glaze made of organic dye on a cross section taken
from a mock panel. Owing to the increased viscosity of the substrate, it was possible to exert a better
control of the application, compared to other tested substrates of lower viscosity. A capillary (application
under the microscope, drop diameter approximately 200 µm) was used to focus the substrate above a
specific layer (the area of interest) (Figure 2a), and the spectrum was recorded (Figure 2b) from the
interface between the substrate drop and the paint layer of interest. Therefore, the precipitation of the
silver onto the larger part of the sample (contamination) was avoided. Despite the low thickness (below
10 mm) of the investigated layer and low concentration of the organic dye, the detection was successful.
On the basis of this study, the advantages of the new photoreduced substrate are attributed especially
to SERS-activity, stability and viscosity.
Figure 2. a) A photomicrograph of a cross section presenting glaze containing an organic dye (marked with an arrow). b) SERS
spectrum obtained on the glaze layer, identifying organic dye Alizarin Carmine (Alizarin Red S).
References
[1] M. Leona, J. Stenger, E. Ferloni, J. Raman. Spectrosc. 2006, 37, 981.
[2] C.L. Brosseau, K.S. Rayner, F. Casadio, C. M. Grzywacz, R. P. Van Duyne, Anal. Chem. 2009, 81, 7443.
[3] F. Casadio, M. Leona, J. R. Lombardi, R. P. Van Duyne, Acc. Chem. Res. 2010, 43, 782.
[4] M. V. Cañamares, J. V. Garcia-Ramos, J. D. Gomez-Varga, C. Domingo, S. Sanchez-Cortes, Langmuir 2005,
21, 8546.
[5] M. V. Cañamares, J. V. Garcia-Ramos, C. Domingo, S. Sanchez-Cortes, J. Raman. Spectrosc. 2004, 35, 921.
83
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OP14
Laser Ablation Surface-enhanced Raman Microspectroscopy
Pablo S. Londero,1* John R. Lombardi,2 and Marco Leona3
Department of Scientific Research, The Metropolitan Museum of Art, New York,
[email protected]
2
Department of Chemistry, The City College of New York, New York
3
Department of Scientific Research, The Metropolitan Museum of Art, New York
1
While Surface-enhanced Raman scattering (SERS) has proved to be a valuable technique for the analysis
of art objects,[1–3] a number of factor have limited the breadth of its applicability. Arguably two of the
greatest are robust methods for adsorbing the analyte onto the SERS-active substrate, and for achieving
microscopic spatial resolution. One technique that is capable of achieving such resolution is tip-enhanced
Raman spectroscopy,[4] but here also the breadth of applications has been limited by the specific sample
preparation required for optimal performance. What is needed, then, is a robust method for SERS
analysis with a high degree of spatial specificity. Here we demonstrate a sample-independent approach
to SERS analysis that requires no solvent, has sensitivity approaching that of mass spectrometry, and
also has spatial resolution as low as 5 _m. By integrating laser ablation micro-sampling with efficient
close-proximity collection of the ablated molecules on an optimized SERS-active surface, we show that
vibrational information can be easily acquired with microscopic spatial resolution and with detection
limits approaching that of mass spectrometry.
The instrument and procedure are illustrated in Figure 1. The Raman microspectrometer, equipped with
a tunable Optical Parametric Oscillator (OPO) source, has been previously described in the literature.[5]
The sample is placed in a small vacuum chamber, on a vertically translating platform. The quartz window
on the top of the chamber is coated on the vacuum side with a 10 nm thick layer of silver nanoislands
that functions as the SERS-active substrate. The window is placed silver-side down, 300 μm from the
sample surface. The chamber is sealed a turbo pump is used to lower the internal pressure to less than
10-4 mTorr. To perform a measurement, the OPO is tuned to the choromophore resonance and a single
7 ns pulse with an energy of 1-100 μJ is typical. Molecules ablated onto the nanoisland film are then
optically excited using a continuous 488 nm ‘read’ laser, typically with a 20X objective at powers of 0.1
mW. The SERS spectrum is collected in the backward propagating direction by the same objective, and
directed into the spectrometer.
This approach, with significant room for improvement, achieves benchmarks approaching those of some
mass-spectrometry techniques with the addition of vibrational information: we’ve observed spatial
resolution of a few micrometers and sub-picogram sensitivity. As a demonstration of the robusteness,
sensitivity and spatial resolution achievable, we performed
ablation-SERS on a film of the water/alcohol-insoluble
pigment copper phthalocyanine (CuPc). Several other
pigment samples have also been tested. The CuPc sample
was evaporated onto a glass coverslip. The prominent 1526
cm-1 B1g mode11 was chosen as the marker for the compound
(see Fig. 2a). An ablated crater of diameter of ~5 μm, shown
in Fig. 2a, deposited sample over a diameter of 310 μm on
the Ag nanoisland film, as measured by the FWHM of the
signal intensity. The crater contour was characterized by Figure 1. Apparatus and measurement sequence for
atomic force microscopy, and corresponds to 42 pg of ablated ablation-based SERS.
material.
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The SERS signal of CuPc was detected using 0.3 mW of laser power with an integration time of 30s and a
1/e2 spot size of 4 μm. The results are shown in Fig. 2b. After ablation, several characteristic sharp peaks
were observed. Using a high-pass Fourier filter to remove broad background we observed a spectral
signature with a signal-to noise ratio (SNR) of 5:1. One can, however, integrate signal for much longer
periods of time from the same ablated sample. In practice we find that linear photodamage from the
488 nm laser is the ultimate limitation to the counting time. In the case of CuPc the signal decays a SNR
of 1:1 in 600 minutes, which results in an instrument limit-of-detection of only 70 fg or 120 attomoles,
approaching that of some mass-spectrometry instrumentation.[4,5] A number of straightforward future
improvements could raise sensitivity by more than 100X, such as increasing the detection laser spot size
on the Ag nanoisland film or applying a more sensitive SERS-active film.
Figure 2. a.) Fourier-filtered SERS spectrum of CuPc film
resulting from a 5 μm ablation spot. b.) SERS spectrum
from ablated sample of dyed ancient Egyptian leather, with
matching reference spectrum for Madder Lake.
As a direct application, we have used ablation-SERS to characterize the colorant in a fragment of dyed
leather from the trappings of an ancient Egyptian chariot. As the colorant was thought to be a complex
of an anthraquinone dye with a polyvalent cation (most likely aluminium), a microscopic sample was
removed, and briefly exposed to hydrofluoric acid vapors in a microchamber. This step has the effect
of hydrolyzing the colorant producing the free anthraquinone, a more volatile species, thus increasing
sensitivity.[8] Without the hydrolizing treatment, no spectrum was observed. The results are shown in
Figure 2c. A strong signal of the dye madder was detected, as can be seen by comparison to the reference
sample. This example clearly shows the applicability of ablation SERS to real-world, complex samples.
This technique has the potential to significantly increase our ability to study modern and ancient complex
samples by SERS. It is a robust and highly sensitive tool for the detection of small-molecule analytes that
can be applied regardless of solubility with excellent spatial resolution and sensitivity comparable to
mass spectrometry techniques.
Acknowledgements
We are indebted to the National Science Foundation (CHE-1041832) for funding of this project.
References
[1]
[2]
[3]
[4]
[5]
[6]
M. Cañamares, J. Garcia-Ramos, C. Domingo, S. Sanchez-Cortes, J. Raman Spectrosc. 2004, 35: 921.
M. Leona, J. Stenger, E. Ferloni, J. Raman Spec. 2006, 37: 981-992.
K. Wustholz, C. Brosseau, F. Casadio, R. Van Duyne, Phys. Chem. Chem. Phys. 2009, 11: 7350-7359.
R. M. Stockle, Y. D. Suh, V. Deckert, R. Zenobi, Chem. Phys. Lett. 2000, 318: 131-136.
P. Londero, M. Leona, J. R. Lombardi, DOI: 10.1002/jrs.4150. Published online: Aug 8, 2012.
T. Sikanen, S. Tuomikoski, R. A. Ketola, R. Kostiainen, S. Franssila, T. Kotiaho, Anal. Chem. 2009; 79:
9134–9144.
[7] L. Alder, K. Greulich, G. Kempe, B. Vieth, Mass. Spec. Rev. 2006, 25: 838-865.
[8] F. Pozzi, J. R. Lombardi, S. Bruni, M. Leona, Anal. Chem. 2012, 84: 3751-3757.
85
Book of Abstracts
OP15
Silver colloidal pastes for the analysis via Surface Enhanced Raman
Scattering of colored historical textile fibers: some morphological
and spectroscopic considerations
Ambra Idone,1,2* Monica Gulmini,3 Francesca Casadio,4 Lisa Backus,4
Lauren Chang,4 Lorenzo Appolonia,2 Richard P. Van Duyne,5 Nilam Shah5
Università degli Studi del Piemonte Orientale “A. Avogadro”, Dipartimento di Scienze e Innovazione
Tecnologica, Italy, +39 0131 360265, [email protected]
2
Regione Autonoma Valle d’Aosta, Direzione Ricerca e Progetti Cofinanziati, Laboratorio Analisi
Scientifiche, Villair di Quart (AO), Italy, +39 0165771700, [email protected]
3
Università degli Studi di Torino, Dipartimento di Chimica, Torino, Italy,
4
The Art Institute of Chicago, Illinois, US, +1 312 8577647, [email protected]
5
Department of Chemistry, Northwestern University, Evanston, Illinois, USA,
1
In recent years Surface Enhanced Raman Spectroscopy (SERS) has become a valid tool to investigate
organic colorants in samples of historical and artistic significance and offers now new analytical strategies
for scientific investigation in the field of art history and conservation.[1] The noble metal substrate
effectively overcomes problems affecting normal Raman spectroscopy, such as high fluorescence due
to the complex chemical environment and lack of signal due to very low concentrations of the molecules
under investigation. The main challenge in performing dye analysis with SERS is the feasibility of
delivering suitable SERS substrates directly on the sample, in order to avoid further treatments of the
sample itself and to minimize down to a micro-scale the fragments that have to be detached from the
artwork.
A variety of SERS substrates have been proposed for art analysis including metal films over nanospheres
(FONs),[2,3] concentrated silver colloids[4] and nanoparticles obtained by in-situ photo-reduction[5]
or laser ablation.[6] Among them, chemically reduced silver colloids are presently the most popular
substrates for SERS in art analysis.
The present work reports the results of a thorough investigation of silver colloids[7] that are concentrated
according to Brosseau et al.[4] (henceforth SC pastes) for analysis of different types of natural fibers
dyed red with brazilwood or cochineal. The morphological, physical and optical characteristics of the
SC paste are investigated and discussed.
Specifically, the SC paste is tested on modern wool and silk dyed with cochineal or brazilwood, as well
as on cotton and flax tinted with brazilwood, at various concentrations. Moreover, historical textiles
from an important collection of Mariano Fortuny (1871–1949) textiles at the Art Institute of Chicago are
examined, in order to test the efficacy of the SC paste on aged samples, and to shed light on whether it
is true that, at a time when the chemical industries were flooding the market with bright and attractive
new industrial products, Fortuny did not use synthetic dyes.
Scanning electron microscopy is employed to highlight the morphological characteristics of the paste
itself and to image the coatings that develop when the paste is spread on the various fibers. Spherical
nanoparticles (30 to 100 nanometers in diameter) with a minority of rod-shaped particles (50 to 200
nm in length) are observed.
SEM images show that the hydrophobic nature of the wool fiber’s surface limits the coverage of the
silver coating, whereas the highly hydrophilic vegetal fibers are almost completely covered. Despite the
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different extent of coverage of the silver coating, areas with a homogenous layer of nanoparticles that is
SERS active were observed in all the considered reference samples.
The SC paste was effective in enhancing the signals of the dyeing molecules of cochineal and brazilwood,
although finding SERS activity was somewhat harder when analyzing wool fibers with respect to
other fibers. Besides the presence of spurious signals from the SC paste itself, the spectra obtained
from reference samples did not show additional peaks that can be attributed to the proteinaceous or
glycosidic fibers.
Regarding the historical samples, the use of natural colorants was confirmed in the Fortuny fiber
samples that were analyzed. Cochineal and brazilwood were found in both the silk velvets and cotton
fibers examined, testifying that a skillful combination of such dyes (here identified simultaneously on
the same fiber with direct extractionless SERS with SC pastes) was put in place to obtain a variety of
different hues contributing to the enduring allure of such beautiful textiles.
Acknowledgements
This work was carried out with the contribution of European Union, of the Regione Autonoma Valle
d’Aosta and of the Italian Ministry of Labour and Social Policy. Support from the Andrew W. Mellon
Foundation and the National Science Foundation through grants CHE-0414554, CHE-0911145,
and DMR-1121262 is also gratefully acknowledged. The RET program at Northwestern University,
sponsored by the Materials Research Science and Engineering Center under NSF grant DMR 0520513,
and its director, Prof. Monica Olvera de la Cruz are also gratefully acknowledged. The SEM work was
performed in the EPIC and facility of NUANCE Center at Northwestern University. NUANCE Center
is supported by NSF-NSEC,NSF-MRSEC, Keck Foundation, the State of Illinois, and Northwestern
University. Anne-Isabelle Henry is thanked for SEM imaging.
References
[1] F. Casadio, M. Leona, J. R. Lombardi, R. Van Duyne, Accounts Chem. Res. 2010, 43, 782.
[2] A. V. Whitney, F. Casadio, R. P. Van Duyne, Appl. Spectrosc. 2007, 61, 994.
[3] N.G. Greeneltch, A. S. Davis, N. A. Valley, F. Casadio, G. C. Schatz, R. P. Van Duyne, N. C. Shah, J. Phys.
Chem. A 2012, 116, 11863.
[4] C. L. Brosseau, A. Gambardella, F. Casadio, C. M. Grzywacz, J. Wouters, R. P. Van Duyne, Anal. Chem.
2009, 81, 3056.
[5] Z. Jurasekova, C. Domingo, J. V. Garcia-Ramos, S. Sanchez-Cortes, J. Raman Spectrosc. 2008, 39, 1309.
[6] M.V. Cañamares, J. V. Garcia-Ramos, S. Sanchez-Cortes, M. Castillejo, M. Oujja, J. Colloid Interf. Sci.
2008. 326, 103.
[7] P. C. Lee, D. Meisel, J. Phys. Chem. 1982, 86, 3391.
87
Book of Abstracts
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Surface enhanced Raman spectroscopy for dyes and pigments –
Can non-invasive investigations become a reality?
Brenda Doherty,1* Brunetto Giovanni Brunetti, 2,3 Antonio Sgamellotti, 2,3
1
Costanza Miliani
1
Istituto CNR di Scienze e Tecnologie Molecolari (ISTM), Dipartimento di Chimica, Università degli
Studi di Perugia, Italy, +39 075 5855638, [email protected], [email protected]
2
SMAArt c/o Dipartimento di Chimica, Università degli Studi di Perugia, Italy
3
Università degli Studi di Perugia, Italy
Surface enhanced Raman spectroscopy in the cultural heritage field is still a relatively new technique
that is progressing in its application for the sensitive and selective detection of natural and synthetic
organic dyes and pigments. Proposed working methods and protocols by leading groups in this field
differ in both active surface preparation and sample pre-treatments. The most commonly adapted
SERS active substrate preparations range from solid state substrates, and variably reduced and stabilized silver colloids [1]. Sample preparations instead range from no preparation whatsoever, to various
extraction and hydrolysis methods often employed to liberate the dye from its pigment complex. All
of the highlighted procedures however, have a common important aim, that is, to identify and characterize the organic colorant/pigment according to accurately compiled in-house databases through
the simultaneous amplification of Raman scattering and fluorescence quenching accounted for by the
electromagnetic and chemical mechanisms. Furthermore, all usable methods are increasingly tailored
towards the many heterogeneous and complex matrices where the dyes and pigments are collocated
including paint films, textiles and paper so as maximise the efficiency and ease of implementation of
the SERS protocol for a practical, systematic and reliable use.
Research conducted in the early 2000s introduced the idea of disposable SERS films by employing a
hydrophilic polymer gel [2]. Regarding dyes and pigments in the cultural heritage field in tapestries and
Japanese prints [3], implemented a cross linked hydroxyacrylate gel combined with a solvent and chelating agent for minimum extraction directly from the artwork followed by SERS analyses. Research in
our laboratory 2011 evidenced a silver colloid doping of methylcellulose for a removable SERS active gel
following measurements on painting lakes [4]. Since then, work by [5], has suggested a doped agar SERS
active matrix to be applied to textiles. Figure 1. SERS spectra of nanocomposite methylcellulose in
function with gel viscosity on a triarylmethane standard.
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This contribution focalizes principally on the optimization of the proposed nanocomposite methylcellulose gel for its use in a non-invasive capacity. It is shown that glucose reduced silver colloids doped
into different viscous grades of methylcellulose permits for an improvement of achieved SERS enhancement as well as a contemporary mechanical improvement enabling a more even gel removal rendering this an adapt SERS substrate as tested by standard synthetic dyes (Figure 1).
Regarding the investigation of pigment lakes, the additional effects of hydrolysis have been approached
so as to evaluate the compromised non-invasive nature over relative enhancements afforded by the
gel so as to arrive to a protocol for its effective use. Furthermore, it is shown that the same colloid has
shown promise when doped into a further natural gel for the creation of a removable film for use on a
paper matrix (Figure 2). All studies have been effectuated utilizing a bench top Raman spectrophotometer and portable Raman instrumentation for movement towards in-situ applications.
Figure 2. Image of a.) a 1mm diameter doped gel on a synthetic dye
on paper and b.) the same gel following SERS measurements and
subsequent total removal.
References
[1]
[2]
[3]
[4]
[5]
F. Casadio, M. Leona, J. R. Lombardi, R. V. Duyne, Accounts of Chemical Research. 2010, 43, 782–791.
S. E. J. Bell, S. J. Spence, Analyst. 2001, 126, 1–3.
M. Leona, U.S. Patent No. 7, 362,431 (9 August 2006).
B. Doherty, B. G. Brunetti, A. Sgamellotti, C. Miliani, J. of Raman Spectrosc. 2011. 42, 1932–1938.
C. Lofrumento, M. Ricci, E. Platania, M. Becucci, E. Castellucci, J. of Raman Spectrosc. 2013. 44, 47–54.
89
Book of Abstracts
OP17
Surface Enhanced Raman Scattering of organic dyes on noble metal
substrates prepared by pulsed laser ablation
N. R. Agarwal,1,2* M. Tommasini,2 P. M. Ossi,3 E. Fazio,4 F. Neri,4
S. Trusso,5 R.C. Ponterio5
Nanostructures, Istituto Italiano di Tecnologia, Genova, Italy, [email protected]
Dipartimento di Chimica, Materiali e Ingegneria Chimica ‘Giulio Natta’, Politecnico di Milano,
Milan, Italy.
3
Dipartimento di Energia and Centre for Nano Engineered Materials and Surfaces, NEMAS,
Politecnico di Milano, Milan, Italy
4
Dipartimento di Fisica e di Scienze della Terra, Università di Messina,V.le Ferdinando Stagno
d’Alcontres 31, 98166, Messina, Italy
5
CNR-IPCF, Istituto per i Processi Chimico-Fisici, Messina, Italy
1
2
Raman spectroscopy is a valuable technique for detecting and characterizing dyes used in ancient
times and helps to assess the geographic origin or dating of artworks. Yet, the Raman spectra of
most of such dyes present a strong fluorescence background or a very low Raman scattering cross
section that prevent the acquisition of well-resolved data, which could be useful as a fingerprint for dye
identification. Surface-enhanced Raman scattering (SERS) can be used to overcome such drawbacks,
in fact, Raman cross sections of molecules adsorbed on artificially roughened noble metal surfaces show
dramatic enhancements as a consequence of the strong amplification of the incident field produced by
the excitation of the localized plasmon resonance modes corresponding to the metallic nanostructure.
Nevertheless, caution should be taken in the identification of SERS spectra of substances. Their
interaction with the metal substrate can result in a drastic modification of the Raman spectrum: Raman
inactive modes can become active, relative intensities between different modes can be altered and also
measurable frequency shift of some vibration modes can be observed. Furthermore, some analytes can
undergo chemical reactions at the metal surface also resulting in drastic changes of the Raman spectra.
Here, we present a study of the SERS behaviour of two dyes of interest in the cultural heritage field:
alizarin and purpurin adsorbed on noble metal nanostructured substrates. Their molecular structures
differ by the presence of an additional hydroxy group in purpurin. Normal Raman measurements
allow distinguishing the two molecules in the high concentration regime, which is a rare condition for
application in artwork analysis. However, identification from SERS measurements may not be easy due
to adsorption mechanism on the substrate together with the presence of different chemical isomers
that can play a role in SERS. In order to investigate this point we performed both SERS measurements
and DFT calculations. Active Ag and Au nanostructured thin films were grown by pulsed laser ablation
in a controlled argon atmosphere. The growth mechanism was studied in detail in previous works.
[1–3]
The control of the surface morphology was achieved by changing the argon pressure and the laser
shots number. All the other relevant deposition parameters like fluence, target to substrates distance
and substrates temperature were kept fixed. This allowed the optimization of the SERS activity as
evidenced by measurements performed using Rhodamine 6G as a test molecule.[4] Au films were grown
in presence of 70 Pa of Ar, at the laser fluence of 1.8 Jcm-2 and with 10000 laser shots.
Surface morphologies (Fig.1) were studied by scanning electron microscopy (SEM). The surface is
characterized by the presence of irregularly shaped islands built by nanoparticles grown during the
plasma expansion as a consequence of the collisions between the plasma and the gas species. Substrates
were soaked into water solutions of pure alizarin and purpurin at different concentration levels
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(between 10–3 and 10–5 M). Micro Raman measurements were carried out using 1064 nm and 632.8 nm
wavelength. SERS spectra were acquired after soaking the gold substrates into the solutions for 1h then
rinsed with deionized water and left to dry in air. Clear spectra of both molecules were recorded on
the substrates. Moreover, the homogeneity of the substrates was checked by performing measurements
on surface area of about 60x60 _m2. DFT calculations were performed on different chemical isomers
of alizarin and purpurin due to the effect of tautomerism. The simulated Raman spectra for these
tautomers are different from each other due to the transfer of a proton from one part of the molecule
to the other which affects the π conjugation within the molecule core. None of the computed Raman
spectra correctly define the experimental Raman spectra since all the tautomers play equivalent role
for obtaining Raman. Statistical analysis on mapping of more than 100 SERS spectra was carried out
to extract useful information and compare it with DFT calculations in order to establish the role of
different tautomeric forms.
Figure 1. SEM image of the surface morphology of
SERS active gold substrate grown by PLD.
References
[1]
[2]
[3]
[4]
P. M. Ossi, A. Bailini, Appl. Phys. A, 2008, 93, 645.
E. Fazio, F. Neri, P. M. Ossi, N. Santo, S. Trusso, Appl. Surf. Sci. 2009, 255, 9676.
C. D’Andrea, F. Neri, P. M. Ossi, N. Santo, S. Trusso, Nanotechnology 20, 2009, 245–606.
N. R. Agarwal, F. Neri, S. Trusso, A. Lucotti, P. M. Ossi, Appl. Surf. Sci. 2012, 258, 9148.
91
Book of Abstracts
OP18
Combining SERS with chemometrics: a promising technique to
assess historical samples with historically accurate reconstructions
Rita Castro,1,2* Maria J. Melo,1,2 Federica Pozzi,3 Marco Leona,3 João Lopes4
Departamento de Conservação e Restauro, Faculdade de Ciências e Tecnologia, Universidade Nova
de Lisboa, Campus Caparica, Portugal, [email protected]
2
REQUIMTE-CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade
Nova de Lisboa, Campus Caparica, Portugal
3
Department of Scientific Research, The Metropolitan Museum of Art, New York, USA
4
REQUIMTE, Laboratório de Química Analítica e Físico-Química, Departamento de Ciências
Químicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
1
In this work a multi-analytical approach was conducted to characterize several dark red organic
microsamples removed from illuminations of 9 manuscripts from three of the most important
monasteries in Portugal: Lorvão, Alcobaça and Santa Cruz, dating from the 12th and 13th centuries.
[1]
In order to achieve a full characterisation, the samples were analysed by micro X-ray fluorescence
(μ-EDXRF), infrared spectroscopy (μ-FTIR), Raman spectroscopy, microspectrofluorimetry[2] and
ultimately Surface-Enhanced Raman spectroscopy (SERS) with chemometrics.
After having identified lac dye by μ-FTIR in selected micro-samples, several lac dye recipes from medieval
treatises were reproduced. The recipes used for these historically accurate reconstructions were taken
from the following sources: Ibn Bādīs ms. (an Arabic manuscript from ca. 1025), Mappae Clavicula
(8-12th centuries), O libro de komo se fazen as kores (a Portuguese treatise from the 15th century),
Bolognese ms. (15th century) and Strassburg ms. (15th century). Two main preparation methods are
distinguished in these treatises: the ones that are prepared without a metal cation (i.e. mordant); and
the ones that formulate an organo-metallic complex, to form a lake pigment. These reproductions were
also fully characterized by infrared spectroscopy and microspectrofluorimetry. The latter revealed to
be promising and the results obtained for the original samples were further confirmed by SERS.
SERS is becoming a valuable procedure for the identification of dyes in microscopic samples. The
experimental procedure was applied to the historical samples and the reconstructions with Ag colloid
obtained by microwave supported reduction of silver sulfate[3] The spectra were obtained with or
without hydrofluoric acid (HF) hydrolysis, for non-complexed dyes and dye-metal complex, respectively.
In the case of historical samples a two-step procedure was conducted (since the type of sample was
unknown), by analyzing the sample first without hydrolysis, and then, after washing the sample, upon
HF treatment[4]
By using this technique it was possible to confirm that the dark red used in Portuguese Romanesque
illuminations was based on lac dye - at the time a luxury colorant commercialized within the Arab
mercantile network. Most of the micro-samples averaged 40 μm in diameter; in some cases it was
possible to use up to 20 μm, making this procedure particularly advantageous for illuminated
manuscripts.
To explore the information obtained in the Raman spectra, in particular if it could carry details on the
process used to prepare the pigment, a chemometrics approach was followed, by applying principal
component analysis (PCA) and hierarchical clustering analysis (HCA). PCA allowed us to distinguish
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sample treatment conditions and pH variations. The spectra reproductions were also analysed by HCA,
enabling a clear separation of pHs of the non-complexed lac dyes. That did not happen as clearly for the
lakes that were submitted to the HF pre-treatment, due to the application of the HF.
This was the first time that lac dye was unequivocally identified in a medieval illumination, and it is
possible to state that its conservation condition is usually good. It is also important to refer that its
colour ranges from dark red, to violet or brownish shades. The historically accurate reconstructions
enable us to propose that these shades may be the result of the processing of the colorant and not of
degradation. The importance of these findings / results for the history and cultural importance of
medieval illuminations will be discussed.
Figures 1, 2. De Avibus (Book of Birds), from the Lorvão monastery (1183-1184), f.6.; SERS spectra of a lac reproduction
(grey line) compared to a microsample from Lorvão 5 f.6 on Ag microwave colloid upon HF treatment (black line), and on
regular Ag microwave colloid without hydrolysis (black dash line). Marked with * are spurious bands due to the colloid.
Acknowledgements
This work has been financially supported by the national funds of FCT-MCTES, through a PhD grant
(SFRH/BD/76789/2011) and project “Colour in medieval illuminated manuscripts: between beauty and
meaning”, PTDC/EAT-EAT/104930/2008. The authors would also like to thank the staff and directory
board of Arquivo Nacional da Torre do Tombo (ANTT), Biblioteca Nacional de Portugal (BNP) and
Biblioteca Pública Municipal do Porto (BPMP) for their generous support and collaboration.
References
[1] M. J. Melo, A. Miranda, C. Miguel, R. Castro, A. Lemos, S. F. Muralha, J. A. Lopes, A. P. Gonçalves, Revista
de História da Arte, FCSH-UNL. 2011, nº1, série W: 152–173 (http://revistadehistoriadaarte.wordpress.
com/).
[2] M. J. Melo, A. Claro, Accounts for Chemical Research. 2010, 43, 857–866.
[3] M. Leona, Proceedings of the National Academy of Sciences. 2009, 106, 14757–14762.
[4] F. Pozzi, J. R. Lombardi, S. Bruni, M. Leona, Analytical Chemistry. 2012, 84, 3751–3757.
93
Book of Abstracts
OP19
Characterization and Identification of Asphalts in Works of Art by
SERS complemented by GC-MS, FTIR and XRF
María L. Roldan,1* Silvia A. Centeno,1 Adriana Rizzo1
1
+1 212 396 5509, [email protected]
Asphalts were used since antiquity for various purposes but they attained use as a pigment in the
sixteenth and seventeenth centuries, and by the eighteenth century they were widely used in oil
painting, ground in turpentine, particularly for glazing, shading and specifically for flesh shadows.
[1,2]
Asphalts were particularly appreciated because of their warm, transparent brown color that can
not be achieved by using any other natural or synthetic pigment. The asphalt originated in the Dead
Sea was specially valued for its great purity and the region is thought to have been the main source of
the pigment between the sixteenth and the seventeenth centuries.[3] Although asphalt pigments have
several properties in common, their composition and chemical properties depend on the source and
on the means used for processing the natural products. Due to their complex nature asphalts are also
among the most difficult pigments to firmly identify in works of art.
Asphalts are mixtures of hydrocarbons with other compounds containing
nitrogen, oxygen and sulphur, and may originate in sediments and rocks,
a form referred to as ‘real asphalt’, or they can be artificial, i.e. derived
from petroleum, coal tar, water-gas tarn, and their pitches. Asphalts have
been reported to be prone to decomposition when exposed to sunlight
and to have a tendency to bleed into other colors,[1] these problems may be
aggravated by unsuitable conservation treatments. Therefore, knowledge
of the composition of these pigments is essential to understand their
interaction with the binding media and to evaluate possible conservation
approaches.
Figure 1. SERS spectra of
In this work, SERS complemented by FTIR, XRF, and GC-MS were
different asphalt pigment
employed to characterize asphalt commercial samples of geological origin,
samples: a) bitumen, b) asphalt
including one from the Dead Sea region, and of bitumen. The SERS spectra
Zecchi, c) asphalt Rublev, d)
of the asphalt samples studied here are shown in Figure 1. The optimized
asphalt Kremer and e) asphalt
methodology was successfully applied to firmly identify these pigments in
from the Dead Sea. λo= 514nm.
microsamples from paintings and other objects in the collection of The
Metropolitan Museum of Art.
Acknowledgements
The authors thank the Andrew W. Mellon Foundation for funding.
References
[1] N. Eastaugh, V. Walsh, T. Chaplin and R. Siddall, The Pigment Compendium: a Dictionary of Historical
Pigments, Elsevier Butterworth-Heinemann: Oxford, 2004.
[2] G. M. Languri, Molecular Studies of Asphalt, Mummy and Kassel Earth Pigments: their Characterization,
Identification and Effect on the Drying of Traditional Oil Paint. Ph. D. Thesis, University of Amsterdam,
2004.
[3] C. I. Bothe, Artists’ Pigments. A handbook of their History and Characteristics, vol. 4, Archetype
Publications: London, 2007, p. 139.
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Study of Raman scattering and luminescence properties
of orchil dye for its nondestructive identification on artworks
Francesca Rosi,1,2* Catia Clementi,3 Marco Paolantoni,3
Aldo Romani,2,3 Roberto Pellegrino,3 Brunetto Giovanni Brunetti,2,3
Witold Novik,4 Costanza Miliani1,2
CNR-ISTM Istituto di Scienze e Tecnologie Molecolari c/o Dipartimento di Chimica, Università degli
Studi di Perugia, Italy
2
Centro di Eccellenza SMAArt Dipartimento di Chimica Università degli Studi di Perugia, Italy
3
Dipartimento di Chimica Università degli Studi di Perugia, Italy
4
Department of Chromatography (CNRS UMR 5648), Laboratoire de Recherche des Monuments
Historiques, Champs-sur-Marne, France
1
Orcein is a natural dye widely used since ancient times for dyeing textiles but also for decorating
miniatures and manuscripts. Known as the “poor person’s purple”, orcein was used in place of the
more expensive Tyrian purple. Unlike the latter, orcein has a low lightfastness and in ancient works it
is often faded. From a chemical point of view, orcein is a complex mixture of different compounds, they
all share a common structure resulting from phenoxazone with a number of different substituents. In
the present work, UV-vis fluorescence combined with micro-Raman spectroscopy allowed for the nondestructive identification of orcein in a fragment from the 9th century Bible de Théodulphe. Raman
spectroscopy has been applied also for studying a parchment fragment sampled from a 16th century
map of Auvergne. In both cases, subtracted shifted Raman spectroscopy (SSRS) has been exploited for
removing the strong fluorescence background. Overall results have been confirmed by LC/MS Q-TOF
analysis.
The electronic and vibrational characterization highlighted a hypsochromic shift of the emission
along with the disappearance of a strong Raman band at about 1560 cm-1 with respect to a fresh
orcein standard sample. Taking into account the poor lightfastness of the purple colorant, the same
investigation has been carried out on artificially aged orcein, by exposure to visible light, reproducing the
spectral modification observed on the ancient fragments. Furthermore, considering that also another
lichen purple dye, namely litmus, shares a similar chemical composition with orcein, a vibrational
investigation has been carried out also on it highlighting spectral analogies with the two investigated
fragments.
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Application to historical samples of in situ, extractionless SERS for
dye analysis
Ambra Idone,1,2* Maurizio Aceto,1 Eliano Diana,3
Lorenzo Appolonia,2 Monica Gulmini3
Università degli Studi del Piemonte Orientale “A. Avogadro”, Dipartimento di Scienze e Innovazione
Tecnologica, Alessandria, Italy, [email protected]
2
Regione Autonoma Valle d’Aosta, Direzione Ricerca e Progetti Cofinanziati, Laboratorio Analisi
Scientifiche, Villair di Quart (AO), [email protected]
3
Università degli Studi di Torino, Dipartimento di Chimica, Torino, Italy, [email protected]
1
Silver colloidal pastes, obtained by concentrating through centrifugation chemically reduced silver
colloids, have been proposed by Brosseau[1] as suitable substrates for in situ extractionless Surface
Enhanced Raman Scattering (SERS) of art samples such as pigment grains and dyed fibers. The
extractionless approach lowers to few nanograms the amount of sample required for the analysis and
thus it is very suitable for investigating historical artworks. As far as sample preparation is concerned,
the main issue consists in achieving a suitable silver coating of the complex surfaces under investigation.
The morphology of the coating in fact plays the major role in promoting signal enhancement. Moreover,
the interpretation of SERS spectra may be difficult due to the possible presence of degradation products,
dust and restoration materials that can contribute to the overall SERS spectrum.[2]
In this work, the potentiality of the application of silver colloidal pastes for the identification of natural
dyes has been explored on various samples obtained from historical textiles and on cross sections
obtained from painted art objects.
Cross sections are usually prepared to investigate multilayered pictorial films, as they may provide
large information with very small sampling. The investigation of such sections is generally carried
out through optical microscopy with visible and UV light, microchemical tests and micro-Raman
spectroscopy.[3] The latter technique generally provides a detailed molecular characterization of
inorganic pigments, but generally fails in the identification of painting lakes,[4] which owe their color to
the presence of organic dyes in small amounts. SERS represents therefore a promising tool overcoming
the lack of information about the dyes used in polychromies.[5]
The textiles samples considered here are few wool bundles detached from the mantle of a cope (probably
dating to XVIth century) conserved in Museo del Tesoro of Aosta’s cathedral (Italy) and a very small
red silk fragment of a unique tapestry dating from the end of XVth century, representing the Deposition
from the Cross and conserved in Milano’s cathedral (Italy). The latter sample was already detached
from the artwork and was recovered during the handling for the ongoing conservation intervention.
In addition, several cross sections obtained by mounting in epoxy resin the polychrome finishing of
wooden statues from Aosta Valley were considered. The corresponding painted areas, analyzed with in
situ X-ray fluorescence spectroscopy, did not evidenced key-elements that might suggest the presence
of a specific pigment, thus indicating that the color was obtained by organic dyes, possibly employed
as lakes.
Historical fibers were mildly pre-treated with water and methanol, in order to reduce the interference
of contaminants on SERS spectra; fibers were then treated with the silver colloidal paste for SERS
investigation. On the other hand, the coating with silver nanoparticles of the polished cross sections
was obtained by employing less concentrated colloids, that allowed to record SERS spectra from the
painting lakes.
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This work demonstrated that silver colloidal pastes are suitable for investigating dyes in different
historical art samples. The concentration of the pastes can be modified according to the specific
sample, in order to achieve the optimal coating for SERS analysis. Surface Enhanced Raman Scattering
permits to deepen the knowledge of the colouring matters used in works of art as it can be applied with
an extractionless approach to very small samples or to cross sections prepared for morphological and
compositional analysis of painted layers.
Acknowledgements
This work was carried out with the contribution of European Union, of the Regione Autonoma Valle
d’Aosta and of the Italian Ministry of Labour and Social Policy.
References
[1] C. L. Brosseau, A. Gambardella, F. Casadio, C. M. Grzywacz, J. Wouters, R. P. Van Duyne, Anal. Chem.
2009, 81, 3056.
[2] C. L. Brosseau, K. S. Rayner, F. Casadio, C. M. Grzywacz, R. P. Van Duyne, Anal. Chem. 2009, 81, 7443.
[3] L. Appolonia, D. Vaudan, V. Chatel, M. Aceto, P. Mirti, Anal. Bioanal. Chem. 2009, 395, 2005.
[4] L. Bellot-Gurlet, S. Pagès-Camagna, C. Coupry, J. Raman Spectrosc. 2006, 37, 962.
[5] F. Casadio, M. Leona, J. R. Lombardi, R. Van Duyne, Accounts Chem. Res. 2010, 43, 782.
97
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Application of surface-enhanced Raman spectroscopy (SERS) to the
analysis of red lakes in French Impressionist and Post-Impressionist
paintings
Federica Pozzi,1* Francesca Casadio1
1
Department of Conservation Science, Art Institute of Chicago, Chicago, USA,
+1(312)443-7209, [email protected]
The Art Institute of Chicago’s collection of Impressionist and Post-Impressionist paintings is the largest
and among the very finest outside of France. The museum’s holdings embrace several invaluable works
of art, including masterpieces by Manet, Monet, Renoir and the influential Post-Impressionist canvases
of Gauguin and Van Gogh.[1] An extensive and systematic technical study of the entire collection of
French 19th century paintings is currently being undertaken, to be published in a comprehensive online
scholarly catalogue.
Scientific analysis is essential to address conservation treatments and help scholars develop a wider
knowledge of the artists’ resources, techniques and original intentions. For Impressionism a strong,
direct relationship can be established between the materials chosen, including ground and paint colours,
and the type of light and tonal effects to be represented. Their practice was also heavily influenced by
the availability of new painting materials originating from the Industrial and Scientific Revolutions,
which led to a significant expansion of the artists’ palette, starting in the 1870s.
The identification of red organic lakes, used by the Impressionists for their brilliant color, is significantly
more challenging than the analysis of most inorganic pigments. Many techniques have been tested over
the decades for this purpose, including UV-visible absorbance [2] and reflectance [3] spectroscopy, thin
layer chromatography (TLC) [4] and high-performance liquid chromatography (HPLC).[5] In most cases,
though, electronic methods are strongly affected by matrix interference and show poor specificity.
On the other hand, chromatographic techniques require relatively large samples, which often cannot
be removed from priceless artifacts. Raman spectroscopy has also been employed to examine both
natural and synthetic pigments.[6,7] However, this technique has its own limitations, first of which is the
inherent weakness of the Raman signals that can be obscured by the molecular fluorescence typical of
some organic materials such as dyestuffs.
Since its discovery in 1974, surface-enhanced Raman spectroscopy (SERS) has been exploited as a
powerful tool for the sensitive and selective detection of organic molecules adsorbed on noble metal
nanostructures.[8] The applications of SERS in the field of cultural heritage materials, and particularly
for the identification of organic colorants, has been widely demonstrated,[9] and latest improvements
have made measurements possible on a single pigment grain or a few-microns length of fiber.[10]
In this work, we will present examples of application of the SERS technique to the detection and
identification of red lakes from masterpieces belonging to the French Impressionist and PostImpressionist collection of paintings of the Art Institute of Chicago. Extensive usage of sometimes
more than one type of red lakes in a single painting will be discussed, as well as the issue of fading.
Comparison of different methodologies to deliver the plasmonic probe to the organic moieties will be
presented. This study enhances the knowledge base of the red lake pigments used by Impressionist
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artists, materials that have so far mostly eluded other comprehensive studies of the Impressionist
palette because of the analytical limitations described above.
Figure 1. On the left, Renoir’s Near the lake,
1879/80; Art Institute of Chicago, oil on canvas, 18 x
22 inches (47.5 x 56.3 cm); Potter Palmer Collection,
accession number 1922.439. On the right, the SERS
spectrum obtained for a red lake sample taken from
the proper left edge of the painting (top) is compared
with a reference spectrum of a commercial madder
lake (bottom).
Acknowledgements
This work has been financially supported by the A. W. Mellon Foundation.
References
[1] G. Groom, D. Druick, The age of French Impressionism. Masterpieces from the Art Institute of Chicago.
Yale University Press: New Haven, London, 2010.
[2] G.W. Taylor, Studies in Conservation. 1983, 28, 153.
[3] M. Leona, J. Winter. Studies in Conservation. 2001, 46, 153.
[4] H. Schweppe, Handbuch der naturfarbstoffe. Landsberg/Lech, Germany, 1993.
[5] M. R. Van Bommel, I. Vanden Berghe, A. M. Wallert, R. Boitelle, J. Wouters, J. of Chromatography A.
2007, 1157, 260.
[6] G. Smith, J. H. Clark, Reviews in Conservation. 2001, 2, 92.
[7] F. Schulte, K. W. Brzezinka, K. Lutzenberger, H. Stege, U. Panne, J. of Raman Spectrosc. 2008, 39, 1455.
[8] P. L. Stiles, J. A. Dieringer, N. C. Shah, R. P. Van Duyne, Annual Review of Analytical Chemistry. 2008, 1,
601.
[9] F. Casadio, M. Leona, J. R. Lombardi, R. Van Duyne. Accounts of Chemical Research. 2010, 43, 782.
[10]F. Pozzi, J. R. Lombardi, S. Bruni, M. Leona, Analytical Chemistry. 2012, 84, 3751.
99
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Surface-Enhanced Raman Spectroscopy (SERS) of historical dyes on
textile fibres: evaluation of an extractionless treatment of samples
Chiara Zaffino,1* Silvia Bruni,1 Vittoria Guglielmi1
1
Dipartimento di Chimica, Università degli Studi di Milano, Italy, [email protected]
Most natural organic dyes are fixed on textiles by mordanting, i.e. by treating the fiber with metal
salts (e.g. aluminium salts) so that the metal ion mediates the interaction between the dye molecule
and the fiber itself. As a result, for SERS analysis of historical textiles it is usually necessary to extract
the dye itself from the ancient artefact by more or less aggressive hydrolysis methods. Of course, the
extraction procedure is time-consuming and leads to the destruction of the sample. For this reason,
in recent times many researchers began to propose various extractionless procedures, to be applied
directly on mordanted textile fibers.[1–-3] Indeed, some of these methods require silver colloids obtained
by unconventional synthesis, such as microwave reduction of Ag2SO4 or in situ photo-reduction of Ag
nanoparticles. On the other hand, Brosseau and co-workers [3] managed to obtain reliable extractionless
non-hydrolysis SERS spectra with citrate-reduced Ag colloids. Similarly to this latest publication, the
present work studies the applicability of a procedure, based on the use of an Ag Lee-Meisel colloid [4] to
obtain SERS spectra directly from fibers. The advantage of using this sol synthesis is its easiness, since
it doesn't require any specific instrumentation. The analyzed fibers are both wool threads dyed in our
laboratory according to historical recipes and ancient textile samples. Reference wool threads had been
washed, treated with alum, KAl(SO4)2 and with acid potassium tartrate and finally dyed,[5] while the
ancient samples analyzed come from textile manufacts belonging to the gallery Moshe Tabibnia, Milan.
Special attention was paid to the possibility to obtain a reliable SERS spectrum from amounts of sample
as small as possible, so that the method can be considered, if not entirely non destructive, at least
micro-destructive and to the possibility to use different excitation wavelengths besides the green one
frequently employed, for example a near infrared radiation as in the FT-Raman technique. As regards
the use of this excitation source, it is well known that different excitation wavelengths can enhance
different vibrational modes in the resulting SERS spectrum: indeed, there are significant differences
between the SERS spectra of our previous database,[6] recorded at 532 nm and the FT-SERS spectra
collected with excitation at 1064 nm. Thus FT-SERS spectra of reference dyes in solution were collected
in order to obtain more suitable references in the near-infrared (NIR) region.
The aim to reduce, as much as possible, the size of the thread used for the analysis has been achieved:
starting from 5 mm of thread initially subjected to analysis, we decreased the sample dimensions, in
most cases, to a single fiber of wool, thus making the technique nearly non-destructive. As regards the
second point, FT-SERS spectra on dyed wool were recorded on a wide range of colorants, leading to the
construction of a new database. It collects spectra of some chromophores and of many natural organic
dyes which belong to several molecular classes, namely anthraquinones, flavonoids, neoflavonoids,
biflavonoids, carotenoids, curcuminoids, naphthoquinones, and gallotannins.
Good results were also achieved on ancient textile samples with the use of an excitation wavelength of
532 nm, while studies about the development of a FT-SERS procedure for the identification of dyes in
ancient samples are still in progress.
References
[1] M. Leona, J. Stenger, E. Ferloni, J. of Raman Spectrosc. 2006, 37, 981–992.
[2] Z. Jurasekova, C. Domingo, J. V. Garcia-Ramos, S. Sanchez-Cortes, J. of Raman Spectrosc. 2008, 39,
1309–1312.
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[3] C. L. Brosseau, A. Gambardella, F. Casadio, C. M. Grzywacz, J. Wouters, R. P. Van Duyne, Analytical
Chemistry. 2009, 81, 3056–3062.
[4] P. C. Lee, D. Meisel, J. of Physical Chemistry. 1982, 86, 3391–3395.
[5] S. Bruni, E. De Luca, V. Gugliemi, F. Pozzi, Applied Spectroscopy. 2011, 65, 1017–1023.
[6] S. Bruni, V. Guglielmi, F. Pozzi, J. of Raman Spectrosc. 2011, 42, 1267–1281.
101
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Suitability of Ag-agar gel for the micro-extraction of organic dyes on
different substrates: the case study of wool, silk, printed cotton and
panel painting mock-ups
Elena Platania,1,2,3* Marco Leona,2 John R. Lombardi,3 Cristiana Lofrumento,1
Marilena Ricci,1 Maurizio Becucci,1,4 Emilio Castellucci1,4
University of Florence, Chemistry Department “U.Schiff”, Italy,
+39 055 4573066, [email protected].
2
+1 (212)3965476, [email protected].
3
Department of Chemistry and Center for Analysis of Structures and Interfaces (CASI), The City
College of New York, USA, +1 (212) 650-6032, [email protected].
4
University of Florence, European Laboratory for Non-linear Spectroscopy (LENS), Italy,
+39 055 4572491, [email protected].
1
Micro-Raman spectroscopy has been a very reliable technique for the characterization of artists’ pigments
and pictorial materials. However, the analysis of organic dyes by means of conventional dispersive
Raman spectroscopy is a very challenging problem. The difficulties encountered in the characterization
of this class of materials stem mainly from their high fluorescence emission upon laser excitation,
which covers the weak Raman signal. Moreover, due to their high tinting power, these compounds are
present at very low concentrations in artifacts. Among the most commonly used techniques for the
identification of dyes, high performance liquid chromatography (HPLC) has been widely employed for
the study of this class of materials in archaeological artworks and historical textiles, due to its ability to
resolve complex mixtures of compounds.[1,2] Despite its high sensitivity, HPLC requires large samples
(1 or 2 mm of a fabric thread) for analysis, raising concerns about the preservation of the physical
integrity of the art object. Although currently available non-invasive methods, such as UV–visible
absorption or fluorescence spectroscopy, help allay concerns about maintaining the integrity of the
artifact, unfortunately, they are of limited use due to their poor specificity. In the last few years, surface
enhanced Raman spectroscopy (SERS) has become a powerful analytical technique for the study of
fluorescent organic materials of artistic interest.
Recently, interesting methods, adopting polymers and sol-gel matrices, have been developed for the
identification of molecules at extremely low concentrations.[3] This aspect has attracted the field of dye
analysis in artworks, providing cutting-edge methodologies for the study of this class of materials,
such as polymeric beads of methacrylate [4] for a non-destructive extraction of dyes from ancient
textiles and drawings; organic modified silicate matrices, combined with zirconium, tailored for a
selective identification of alizarin;[5] methylcellulose active films for the detection of painting lakes[6]. In
particular agar-agar, successfully applied in the field of stone works,[7] paintings[8] and paper cleaning,[9]
and combined with silver nanoparticles for the production of antibacterial organic-inorganic systems,
[10]
has been selected as an ideal gelling material for our research. As introduced in a previous work [11],
a nanocomposite Ag-agar hydrogel has been developed for non-destructive extraction of dyes from
artworks.
The nanocomposite gel has enabled the accomplishment of two important goals. In fact, it acts not
only as an absorbent probe for the micro-extraction of dye molecules from textiles, but also as efficient
enhancer of Raman scattering, due to the silver nanoparticles trapped in its structure. The system has
been found to be extremely stable, easy to use and to produce, minimally invasive, easy to store and
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able to be analyzed even after long time intervals, maintaining unaltered its enhancement properties
without detriment of the extracted compound. Moreover, the shrinkage of the gel upon drying makes it
an excellent mechanical molecular trap for the silver nanoparticles, which approach each other as the
network volume decreases. This process generates high plasmonic electromagnetic fields that engender
the Raman signal amplification.[12]
In this work, Ag-agar gel, successfully applied for the micro-extraction of anthraquinone dyes on
cotton, have been tested on new different substrates, such as wool, silk, printed cotton and panel
painting mock-ups, for the detection of alizarin, purpurin, carminic acid and laccaic acid. Microextractions have been performed also on pieces of printed cotton dyed with unknown dyes. SERS
measurements, of the nanocomposite matrix,
have revealed the presence of alizarin. Cross
reference HPLC analyses, performed on the
same pieces of textile, have confirmed the SERS
results, showing the suitability of the technique.
Ag-agar gel has been synthesized adding new
chemicals within its structure, such as chelating
agents (EDTA) and aggregating salts (KNO3) in
order to improve both the dye micro-extraction
and the enhancement of the Raman scattering.
Acknowledgements
This work was supported primarily by the
Department of Justice Office of Justice Programs,
National Institute of Justice Cooperative
Agreement 2009-DN-BX-K185. and partially by
the Center for Exploitation of Nanostructures in
Senor and Energy Systems (CENSES) under NSF
Cooperative Agreement Award Number 0833180.
Figure 1. SERS spectrum of alizarin collected after microextraction by Ag-agar gel/EDTA on a piece of silk dyed with madder
and mordented with alum.
References
[1]
[2]
[3]
[4]
[5]
Z. C. Koren, J. Soc. Dyers Colour. 1994, 110, 273.
I. Degano, E. Ribechini, F. Modugno, M. P. Colombini, Appl. Spectrosc. Review. 2009, 44, 363.
S. E. J. Bell, S. J. Spence, Analyst. 2001, 126, 1.
M. Leona, P. Decuzzi, T. A. Kubic, G. Gates, J. R. Lombardi, Anal. Chem. 2011, 83, 3990.
S. Murcia-Mascarós, C. Domingo, S. Sanchez-Cortes, M. V. Cañamares, J. V. Garcia-Ramos, J. Raman
Spectrosc. 2005, 36, 420.
[6] B. Doherty, B. G. Brunetti, A. Sgamellotti, C. Miliani, J. Raman Spectrosc. 2011, 42, 1932.
[7] E. Campani, A. Casoli, P. Cremonesi, I. Saccani, E. Signorini, Quaderno n.4/CESMAR7, Il Prato, Padova,
2007.
[8] E. Carretti, M. Bonini, L. Dei, B. H. Berrie, L. V. Angelova, P. Baglioni, R. G. Weiss, Acc. Chem. Res. 2010,
43, 751.
[9] S. Iannuccelli, S. Sotgiu, Quaderni, Gangemi: Roma, 2010.
[10]S. Ghosh, R. Kaushik, K. Nagalakshmi, S. L. Hoti, G. A. Menezes, B. N. Harish, H. N. Vasan, Carbohydr.
Res. 2010, 345, 2220.
[11] Lofrumento C., Ricci M., Platania E., Becucci M., Castellucci E., J. Raman Spectrosc. 2012, 44, 47.
[12]P. Aldeanueva-Potel, E. Faoucher, R. A. Alvarez-Puebla, L. M. Liz-Marzàn, M. Brust, Anal. Chem. 2009,
81, 9233.
103
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PB15 polymorphic distinction in paint samples by combining microRaman spectroscopy and chemometrical analysis
Jolien Van Pevenage,1* Cathérine Defeyt,2 Luc Moens,1 David Strivay,2 Peter
Vandenabeele3
Ghent University, Department of Analytical Chemistry, Raman Spectroscopy Research Group, Ghent,
Belgium, +32 9 2644719, [email protected]
2
Centre Européen d’Archéometrie and Institut de Physique Nucléaire, Atomique et de Spectroscopie,
Universié de Liège, Belgium, [email protected]
3
Ghent University, Department of Archaeology, Archaeometry Research Group, Ghent, Belgium, Peter
[email protected]
1
In art analysis of 20th century artworks, copper phthalocyanine (CuPc) is often identified as an important
pigment (PB15). It is used in different polymorphic forms and identification of the polymorph could
retrieve information on the production process of the pigment, at the time.
This pigment can be detected by Raman spectroscopy, which is a molecular spectroscopic technique.
Moreover, Raman spectroscopic analysis makes it possible to discriminate between polymorphs
of crystals. However, in the case of PB15, spectral interpretation is not straightforward. In order to
discriminate the polymorphs of PB15 in paints, Raman data treatment requires some improvements.
Here, Raman spectroscopy is combined with chemometrical analysis in order to develop a procedure
allowing us to identify the PB15 crystalline structure in painted layers and in artworks. To be able
to discriminate between different CuPc polymorphs, different chemometrical approaches were first
tested on pigment samples. And in a second stage, the selected procedure was extended towards paint
samples.
In the developed procedure, after manual baseline correction of the spectra, 12 intensity ratios of certain
band positions were selected to be used as input to linear discriminant analysis (LDA).[1] 10 of these
band ratios had been proposed in a recent study [2] as polymorphic markers. From our observations,
two supplementary intensity ratios (I1141 / I1105 and I775 / I715) could also contribute to our aim. Further,
the band ratios were vector-normalised for all the spectra in the dataset.
As linear discriminant analysis is a supervised classification method, the dataset has to be split in a
training set – used to develop the classification model – and a validation set, to evaluate the outcome
from the analysis. The best results were obtained using leave-one-out classification. In this classification
method, each case (or spectrum) included in the analysis is classified by the functions derived from all
cases other than that case.
Applying the developed procedure to a dataset, that includes Raman spectra of pigments and paint
samples on the one hand, and only paint samples on the other hand, it turns out that in general, it is
possible to discriminate between different CuPc polymorphs. In the first case, we observe that 92% of
the paint samples are correctly classified. In the latter case, the results are even better, and a correct
classification of 96% is observed.
So in the end there can be concluded that the combination of Raman spectroscopy and LDA (using
intensity ratios and evaluated by the leave-one-out algorithm) is a very valuable non-destructive
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method to identify the crystalline structure of a PB15 pigment in painted layers.
Acknowledgements
The authors wish to acknowledge the MEMORI project for its financial support. The MEMORI project,
‘Measurement, Effect Assessment and Mitigation of Pollutant Impact on Movable Cultural Assets.
Innovative Research for Market Transfer‘ is supported through the 7th Framework Programme of the
European Commission (http://www.memori-project.eu/memori.html).
References
[1] G. Darren, P. Mallery. SPSS For Windows. Needham Heights, Massachusetts: Allyn & Bacon, 2001.
[2] C. Defeyt, P. Vandenabeele, B. Gilbert, J. Van Pevenage, R. Cloots, D. Strivay, J. of Raman Spectrosc. 2012,
43(11), 1772–1780.
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First identification of the painting technique in 18th Century
Transylvanian oil paintings using micro-Raman and SERS
Oana-Mara Gui,1,2 Simona Cînta-Pînzaru3*
Technical University Cluj-Napoca, Faculty of Materials’ Science and Engineering,
Cluj-Napoca, Romania, [email protected]
2
University of Art and Design Cluj-Napoca, Cluj-Napoca, Romania
3
Babes-Bolyai University, Biomedical Physics, Theoretic and Molecular Spectroscopy Dept., Cluj
Napoca, Romania, [email protected]
1
The investigation of cultural heritage objects has become increasingly centered in the past decade on
the characterisation of the materials and the painting techniques.[1] as a means of better understanding
historic context, conservation state and of projecting future restoration work. In such context, Raman
spectroscopy proves to be a versatile tool in what it can offer insight into the nature of both organic and
inorganic materials, without damaging the sample and often enabling in-situ characterisation of the
artwork.[2]
Here we report the first identification of the painting technique of two 18th century portraits of the
Transylvanian noble family Banffy using SERS. Although recent investigations into clerical Romanian
art shed light on the preferred painting technique of the local craftsmen (mostly, egg-based tempera
[3]
) no information was available on the art comissioned by noblemen. In order to better understand
such cultural heritage items, micro-samples were removed from both the paint layers and the canvas
supports of the paintings and were subjected to analysis with little or no preparation.
Aiming to reduce the amount of pictorial material sampled, micro-Raman and SERS measurements
were carried out directly on paint micro-samples and linen threads and allowed simultaneous
identification of both organic and inorganic painting components, including the canvas support. MicroRaman was also performed on paint cross-sections, in order to better localize painting material into
the different layers.
Investigations revealed a western European painting technique which made use of a lipid binder
and two differently colored preparation layers. Raman investigations showed that artists used both
common pigments for the Transylvanian region such as lamp black (having characteristic Raman
peaks at 1330 and 1590 cm-1) as well as the uncommon or even expensive pigments such as massicot
(showing characteristic peaks at 135 (s), 267 (m) and 362 (w) cm-1) and vermillion (252 (s) and 342 (m)
cm1 [Clark et al, 1997]), which was surprisingly found in the preparation layers. SERS analyses of the
canvas support suggested that a high lignin containing fiber was used, as aromatic ring deformations
[5]
were observed together with a huge band at 238 cm-1 which is due to the chemisorption of lignin on
Ag nanoparticles. Moreover, due to the fluorescence quenching effect of the SERS substrate, bands of
the cellulose could also be observed even when using a 785 nm wavelength excitation laser: the δ(CCC)
ring deformation at 466 cm-1, the ρ(CH2) broad band at ~960 cm-1 or the ν(COC) glycoside doublet at
1100 cm-1.[6]
To the best of our knowledge this is the first attempt to characterize Transylvanian oil paintings dating
before the 1800s.
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Acknowledgements
This work has been financially supported by the QDOC project, contract no. POSDRU/107/1.5/S/78534.
The authors would like to thank the Cluj-Napoca Art Museum for providing samples and photographs
of the oil paintings.
References
[1] C. Ricci, I. Borgia, B. G. Brunetti, C. Miliani, A. Sgamellotti, C. Seccaroni, P. Passalacqua, J. Raman Spectrosc.
2004, 35, 616–621.
[2] P. Vandenabeele, M. C. Christensen, L. Moens, J. Raman Spectrosc. 2008, 39, 1030–1034.
[3] M. Guttmann, Journal of Cultural Heritage. 2012, http://dx.doi.org/10.1016/j.culher.2012.10.009.
U. P. Agarwal, R.S. Reiner, J. of Raman Spectrosc. 2009, 40, 1527–1534.
[4] H. G. M. Edwards, N. F. Nikhassan, D. W. Farwell, P. Garside, P. Wyeth, J. of Raman Spectrosc. 2006, 37,
1193–1200.
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Organic materials in oil paintings and canvas revealed by SERS
Oana-Mara Gui,1,2 Simona Cînta-Pînzaru3*
Technical University Cluj-Napoca, Faculty of Materials’ Science and Engineering, Cluj-Napoca,
Romania, [email protected]
2
University of Art and Design Cluj-Napoca, Cluj-Napoca, Romania
3
Babes-Bolyai University, Biomedical Physics, Theoretics and Molecular Spectroscopy Dept,
Cluj-Napoca, Romania, [email protected]
1
The characterisation of organic materials used in oil paintings is a
great challenge for any Raman technique. We summarize here our
recent results in the topic, using surface enhanced Raman scattering
(SERS) to analyse new and artificially aged organic materials.
This current work on organic painting materials presents an innovative
approach to artwork and especially plant fibre analysis based on the
use of different SERS-active colloidal nanoparticles. The investigated
materials included new and artificially aged oil painting replicas, as
well as samples form cultural heritage canvases of Romanian and
Italian origin, dating from 1700 to 1900. Materials were chosen to
cover different variations of the same technique (oil painting) as well
as different stages of ageing. All samples were subjected to analysis
without any prior preparation.
The most interesting results were obtained for the canvas supports,
where lignin bands were enhanced after direct immersion in Ag
colloidal solutions and specific Raman bands corresponding to
aromatic ring could be observed between 300 and 1600 cm-1 (Figure 1
A) [1] Because of the huge fluorescence signal of the fibers to any laser
lines from visible to NIR, we employed surface enhanced Raman
scattering to exprore the possibility to detect trace amounts of species
that are not available in normal Raman measurements.
Taking into account that lignin counts for less than 4% in the pure linen fibre, this is not detectable in
a normal Raman experiment of linen.
For SERS analysis, the chemisorption of lignin is proven by the huge band at 238 cm-1 which appeared
in all canvas samples. As compared to FT-Raman analyses carried on the same samples, SERS proved
to be advantageous because it allowed for a very fast detection of lignin (total analysis time was under
30 seconds) while providing a less fluorescent spectrum. The FT-Raman spectrum acquired on the
same sample prior to SERS and consisting of 1000 acquisitions shows a weaker and more fluorescent
signal (Figure 1 B). Although SERS does not enhance cellulose signals, the background quenching
effect of SERS enabled the observation of bands specific for the polysaccharide such as the glycosidic
doublet around 1100 cm-1 [2].
Another significant advantage of SERS is the possibility to evidence traces of protein species in the
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samples. A complex band at 1650 cm-1 could be detected on linen fibres from the 1835 painting, thus
hinting towards a contribution from the amide I band characteristic for proteins. For protein samples
(animal glue), Ag nanoparticles allowed the detection of the amide I band at 1658 cm-1 together with the
amide V band at 730 cm -1 (not shown here). No SERS effect was observed when employing the Ag NPs
on lipid binders. This allows for a fast discrimination between protein-based and lipid-based materials
within complex samples, and has application in paint cross-section analyses by SERS [3].
The study enabled the selection of the best colloidal nanoparticles for SERS enhancement of bands
characteristic for plant-based fibres and other organic materials employed in canvas painting. By
making use of low laser power and low integration times while also providing reproducible results, this
SERS approach to investigating binding media and canvas supports has great potential for either in situ
applications or cross-section analysis of heritage samples.
Acknowledgements
This work has been financially supported by the QDOC project, contract no. POSDRU/107/1.5/S/78534.
The authors are grateful to the Cluj-Napoca Museum of Art for providing samples from Romanian
cultural heritage paintings and to restorer Belinda Giambra and Soprintendenza dei BB.CC.AA.
Caltanissetta for samples from the Italian painting.
References
[1] M. O. Gui, A. Falamas, L. Barbu-Tudoran, M. Aluas, B. Giambra, S. Cinta Pinzaru., J. of Raman Spectrosc.
2013, 44, 277–282.
[2] P. Adapa, C. Karunakaran, L. Tabil, G. Schoenau, Agricultural Engineering International: CIGR Journal.
Manuscript 1081. 2009, XI.
[3] L. H. Oakley, S. A. Dinehart, S. A. Svoboda, K. L. Wustholz, Analytical Chemistry. 2011, 83, 3986–3989.
109
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Characterization of SOPs in acrylic and alkyd paints by means of
µ-Raman spectroscopy
Marta Anghelone,1,2* Dubravka Jembrih-Simbürger,1 Manfred Schreiner1,2
Institute of Science and Technology in Art, Academy of Fine Arts, Vienna, Austria,
+43 1 58816 8662, [email protected], D. [email protected],
[email protected]
2
Institute of Chemical Technologies and Analytics, Analytical Chemistry Division, Vienna University
of Technology, Vienna, Austria
1
Synthetic modern materials are nowadays used in all fields of contemporary art and their study is
getting of primary importance, particularly to understand how they interact with each other and
how they behave with time, aming to establish appropriate preservation and conservation strategies.
Therefore, a systematic investigation of synthetic organic pigments (SOPs), above all phthalocyanines,
and modern binding media, such as acryl and alkyd, have been carried out. Since Raman spectroscopy
proved to be a particularly appropriate tool to be employed for this purpose, [1] the method was included
in the study.
Figure 1. Raman spectra obtained with
an excitation wavelength of 532 nm for
phthalocyanine blue pigment (PB15:3),
acrylic binding medium (Plextol) and for a
mixture of both, PB15:3 + Plextol.
The aim of this work is to evaluate the influence of different excitation wavelengths and of the
presence of binding media on the characterization of SOPs by means of µ-Raman spectroscopy [2].
Thus, Synthetic Organic Pigments representative for different chemical classes [3] were collected
from various manufacturers and used for preparing mock-ups. Therefore the pigment powders were
mixed with binders (Plextol: n-butylacryl/ methylmethacrylate) and alkyd resin (Lukas medium 4) of
known chemical composition and cast on glass slides. The thickness of the paints was 150 µm (wet).
The homogeneity, thickness and aspect of the paint layers was studied and documented by optical
microscopy on cross-sections. For the preparation of mock-ups no additives were employed, in order to
obtain a simple two component (pigment-binder) system. Finally, pure pigment powders, pure binding
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media and mock-up samples were analysed performing µ-Raman spectroscopy. Three excitation
wavelengths (532, 632.8 and 785 nm) were employed in order to observe and to compare the effects
caused by the presence of binding media, trying to avoid fluorescence. In particular the attention was
focused on phthalocyanine blue and green pigments,[4] on the identification and classification of their
polymorphs,[5] and on the interaction with the binding media. The results show that pure pigments and
pure binding media can be easily identified in a range between 200 and 1800 cm-1, especially using 532
nm and 632.8 nm lasers for the excitation. In the case of mock-up samples, µ-Raman measurements
allowed to identify the pigments despite the presence of the binding medium. By extending the range of
acquisition to 3500 cm-1, it was possible to detect the binder itself (Figure 1).
An excitation wavelength of 532 nm was found to be particularly suitable, while adopting a 632.8 nm
laser, fluorescence effect was present. Nevertheless an identification of the components (pigments and
binders) could be achieved.
References
[1] C. Scherrer, S. Zumbuehl, F. Delavy, A. Fritsch, R. Kuehnen, Spectrochimica Acta Part A, 2009, 73, 505.
[2] K. Trentelman, C. Havlik, M. Picollo (Editor), The Sixth Infrared and Raman Users Group Conference
(IRUG6), Il Prato, Italy, 2004, p. 94.
[3] S. Q. Lomax, T. Learner, J. of the American Institute for Conservation, 2006, 45(2), 107.
[4] D. R. Tackley, G. Dent, W.E. Smith, Physical Chemistry Chemical Physics, 2001, 3, 1419.
[5] M. A. Shaibat, L. B. Casabianca, D. Y. Siberio-Pèrez, A. J. Matzger, Y. Ishii, Journal of Physical Chemistry
B. 2010, 114(13), 4400.
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Synthetic Polymers and Cultural Heritage. An Analytical Approach
by Raman Spectroscopy
Margarita San Andrés,1* Valentín G. Baonza,2 Oscar R. Montoro,2
Adrián Bouzas,2 Ruth Chércoles,1 Mercedes Taravillo,2
José Manuel de la Roja1
Universidad Complutense, Facultad de Bellas Artes, Dpto. de Pintura-Restauración, Madrid, Spain,
+34 91 394 36 40, [email protected]
2
MALTA-Consolider Team & QUIMAPRES Team, Departamento de Química Física I, Facultad de
Ciencias Químicas, Universidad Complutense de Madrid, Spain, +34 91 394 42 62,
[email protected]
1
Since the middle of last century, the use of synthetic polymers has widely spread in the field of heritage.
These new materials have been used by modern and contemporary artists, so they are an important
part of the collections of Museums, for example, MNCARS (Madrid), Tate Gallery (London) and MOMA
(New York). On the other hand, they are commonly used in preventive conservation tasks, such as:
packaging, exhibition, handling and storage. In these cases, these materials are used for supports,
protectors and/or thermal and electrical insulators. Synthetic polymers are also part of materials applied
in restoration of artworks, for example, as coatings, adhesives, fixatives, varnishes and consolidants.
However, existing synthetic polymers and related materials are rarely developed to be specifically used
in the field of heritage. Furthermore, the information provided by the manufacturer is quite limited
and sometimes inaccurate. For these reasons, it is necessary to achieve the data about its composition
and long-term behavior, considering that both issues are in fact closely related. In order to perform
such investigation it must be recognized that commercial products are often complex materials, since,
apart from the polymeric matrix, many other components may be present. The most common added
components are plasticizers, lubricants, pigments, extenders, fillers, colorants, antioxidants, and/or
UV absorbents, among others. Some components, like plasticizers and lubricants, are added for easy
processing, while others, like pigments and antioxidants, help to improve the properties and features of
the final product. In any case, regardless the function of the additives, they must be identified and their
stability must be also known, especially if they are part of artworks or will be in contact with them.
There are several analytical techniques which are suited for identifying polymeric materials.[1] The
most common are: chromatographic (GC-MS and Py-GC-MS), thermal analysis (DSC and TGA) and
vibrational spectroscopic techniques. With respect to the latter, Fourier transform infrared (FTIR)
is very useful and has been used in analytical characterization of polymers relevant in conservation
and restoration.[2] It is also useful for assessing the behavior of polymeric materials with aging,
although such studies usually benefit from complementary analyses with other techniques, especially
chromatographic and thermal analyses.[3,4]
As it is well known, Raman and FTIR spectra provide complementary information, since weak FTIR
absorptions usually show strong Raman features and vice-versa. On the other hand, in the case of
polymeric materials, Raman spectroscopy provides useful information about chain´s orientation,
crystallinity and the evolution of these properties with the aging process. The study of all of these
factors is important because they modify the physical properties of plastics and also their practical
uses.[5]
In order to improve the Raman spectroscopic data existing about commercial materials used in tasks
of preventive conservation, here we present the analysis carried out in some selected products. The
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materials analyzed include adhesives, nonwoven fabrics, supports, insulating materials and foams.
Some of them are polymer blends and composite materials.
Experimental
The materials analyzed in this work are: Cellaire®, Ethafoam®, Plastazote®, Lampraseal®,
Marvelseal®, Tyvek® tape, BEVA® Film 371, Melinex®, Polyfelt, Lexan®, Coroplast®, Polionda®
and sheet JCR. The samples were characterized by a confocal micro-Raman spectrometer (BWTEK
VoyageTM BWS435-532SY) coupled to an Olympus BX51 microsco-pe. Raman spectra are taken at room
temperature by using a 532.0 nm laser line at a power of 2-3 mW. The excited Raman scattering signal
is collected through a 20x long working distance objective. The spot size of the incident light is about
8 μm2 on the sample. Our results cover the 100–3750 cm−1 spectral range and their spectral resolution
was 3.8 cm−1.
Results
The polymers identified have been polyolefins, polyesters, polyamides, polycarbonates and others.
Figure 1 contains Raman spectra corresponding to a foam film, marketed as Cellaire®, and a plastic
sheath, marketed as sheet JCR. Cellaire® presents characteristic bands attributed to a low-density
polyethylene (2882, 2848, 2722, 1459, 1440, 1295, 1127 and 1062 cm−1) and sheet JCR shows features
that suggest that is a polyethylene terephthalate (3084, 1728, 1616, 1098 and 563 cm−1). Raman spectra
of the other samples investigated have allowed their analytical characterization.
Figure 1. Raman spectra for
Cellaire® and sheet JCR.
Acknowledgements
This work has been funded by the Spanish Ministry of Science and Innovation under Projects
CTQ2010-20831, CTQ2012-38599-C02-02 and MALTA-Consolider Ingenio 2010 (CSD2007-00045).
The authors are also grateful to the Science and Technology of Heritage Conservation Laboratory
Network (RedLabPat), CEI, Moncloa Campus (UCM-UPM) and Comunidad de Madrid and EU though
the QUIMAPRES-S2009/PPQ-1551 program.
References
[1] M. J. Forrest, Analysis of Plastics. Rapra Review Reports. Expert overviews covering the science and
technology of rubber and plastics, vol. 13, nº 5, Smithers Rapra Press: Shrewsbury, 2002.
[2] R. Chércoles, M. San Andrés, J. M. De la Roja, M. L. Gómez, Analytical and Bioanalytical Chemistry,
2009, 395, 2082–2096.
[3] M. Lazzari, A. Ledo-Suárez, T. López, D. Scalarone, M. A. López-Quintela, Analytical and Bioanalytical
Chemistry, 2011, 399, 2939–2948.
[4] M. San Andrés, R. Chércoles, S. Santos, J. M. de la Roja, C. Domínguez, M. L. Gómez, Science and
Technology for the Conservation of Cultural Heritage, Taylor & Francis: Oxford, 2013 (in press).
[5] Y. Shashoua, Conservation of plastics. Materials science, degradation and preservation, ButterworthHeinemann: London, 2008, pp. 93–95.
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Raman monitoring of the sol-gel process on OTES/TEOS hybrid sols
for the protection of historical glasses
L. de Ferri,1 A. Lorenzi,2,3 P. P. Lottici,2,4 A. Montenero2,3
Chemistry, Materials and Chemical Engineering Department, Politecnico di Milano, V. L., Italy,
2
CIPACK Center, Parma, Italy
3
Chemistry Department, Università degli Studi di Parma Parco Area delle Scienze 17/A, Parma, Italy,
4
Physics and Earth Sciences Department, Università degli Studi di Parma, Parma, Italy,
1
In the frame of a wider research work focused on the study of Medieval Potash-Lime-Silica (PLS) glass,
several hybrid sols have been studied as water repellent protective coating for historical windows.
The sol gel process currently is one of the most used methods to study new chemical products for the
conservation of the Cultural Heritage.
For historical windows the sols should achieve the protection from the most diffused weathering agents
(SOx, NOx, CO2…) dissolved in the environmental water that acts like a trigger for the glass alteration
mechanisms.
Currently the protection of historical windows is achieved by the installation of protective glazing
on the external surface of the windows or by the application of resins. In the first case the slabs
strongly reduce the transmission of light, darkening the glasses colours and having a bad impact on
the appearance of the monuments [1]. The acrylic resins have, as main drawbacks, the physical and
chemical incompatibility with the inorganic substrate, the occurrence of yellowing phenomena due to
the photo-oxidation and the thermal instability since their Tg range between 15 and 40°C [2].
In this work TEOS (Tetraethylorthosilicate) based sols -in isopropanol as solvent and using HCl as
catalyst- have been added with several functionalized Si-alkoxides in different proportions to achieve
good surface water repellency. Three compositions are particularly effective: 80%TEOS-20%OTES
(Octyltriethoxysilane), 95% TEOS-5% HDTMS (Hexamethyltrimethoxysilane) and 75%TEOS20%OTES-5%HDTMS.
The sol gel process was followed by Raman spectroscopy to study the evolution of some peaks suitable
to monitor the hydrolysis and the condensation reaction and the results of the investigation on the
80%TEOS-20%OTES composition are reported here.
Since the isopropanol and ethanol (reaction by-product) Raman features are particularly intense, to
obtain strong alkoxide Raman features the spectra were acquired on a sol containing an higher Si
concentration (2M) with respect to those originally used as protective coatings (0.5 M) and working
at pH~5, instead pH~2, to slow down the reaction kinetics and then better follow the changes of the
Raman features.
The intensity decrease of the TEOS features at 652, 930 and 1090 cm-1 indicates the progress of the
hydrolysis reaction. In particular, the symmetric stretching modes of the Si-O bonds of both alkoxides
at ≈ 650 cm-1 completely disappear after 10 minutes, indicating that the reaction was completed [3].
The evolution of the Si-O anti-symmetric stretching peak at ≈795 cm-1 can be used to follow the
condensation reactions. This mode initially is found to increase in intensity with the number of
hydrolyzed alkoxide molecules. Then its intensity decreases since the condensation gives the formation
of siloxanic -Si-O-Si- groups [4]. This is confirmed by the intensity of the 1047 cm-1 peak, attributed to
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the asymmetric stretching motions of the Si-O-Si bonds, which increases over the reaction time.
The process was followed for 48 hours: the typical large silica band appears between 250 –450 cm1
, together with changes –in intensity and position– in the high frequency region concerning the
stretching motions of the C–H groups.
The Raman monitoring of the sol-gel process to follow the hydrolysis and condensation reactions proved
to be a fast and easy way to understand the changes occurred in the system over the reaction time.
References
[1] I. Pallot-Frossard, A. Bernardi, R. Van Grieken, S. Rolleke, M. Verità, Rivistadella Stazionesperimentale
del Vetro. 2005, 35, 75–83.
[2] O. Chiantore, M. Lazzari, Polymer. 2000, 42, 17–27.
[3] I. G. Marino, P. P. Lottici, D. Bersani, R. Raschella, A. Lorenzi, A. Montenero, Journal of Non-Crystalline
Solids. 2005, 351, 495–498.
[4] M. Gnyba, M. Jędrzejewska-Szczerska, M. Keranen, J. Suhonen, Proceedings, XVII IMEKO World
Congress, June 22–27, 2003, Dubrovnik, Croatia, 2003, 237.
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Possible differentiation with Raman spectroscopy between synthetic
and natural ultramarine blues. Comparative analysis with the blue
pigment of a painting of R. Casas (1866-1932)
A. R. De Torres,1 S. Ruiz-Moreno,1 A. López-Gil,2 P. Ferrer,2 M. C. Chillón2
Universitat Politècnica de Catalunya, Barcelona, Spain, (34) 934016443,
2
Actio Arte y Ciencia, Barcelona, Spain, (34) 934054608
1
This work deals with the possible differentiation among several synthetic ultramarine blue pigments,
which in turn, are compared with a natural ultramarine blue (lazurite) from Afghanistan. For that
purpose, three synthetic pigments manufactured by Nubiola (trademark) have been characterized with
Raman spectroscopy. The fundamental molecular structure of these synthetic pigments is
where 0 ≤ x ≤ 1 and 2 ≤ y ≤ 4.
(Na8-xAl6-xSi6+xO24)Sy
The results have demonstrated that it is possible to detect appreciable differences in both, the Raman
frequencies and relative intensity values. However, it is remarkable that none of the obtained spectra
matches with the lazurite mineral spectrum. On the other hand, one of the synthetic pigments (NUB1)
shows a Raman spectrum which is identical to the measured in the blue areas of an easel painting by
the modernist Catalonian painter Ramón Casas i Carbó (Barcelona, 1866-1932).
Therefore these results indicate that it seems possible to discern among natural ultramarine blue and
its several synthetic imitations. In figure 1, the obtained spectra for synthetic pigments, blue painting
and lazurite are shown: NUB1 and R. Casas; NUB2; NUB3; and lazurite. Note that NUB1 and R. Casas
are identical.
Figure 1. Raman spectra of three synthetic
ultramarine pigments (NUB1, NUB2 and
NUB3) and Raman spectrum of lazurite from
Afghanistan. The Raman spectrum obtained
in the R. Casas painting coincides with NUB1
spectrum.
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The observed Raman shifts and the variations in the relative intensities are especially relevant in the
Raman bands associated with the S3- anion, which is the responsible chromophore of the blue hue in
these pigments. Positional differences about 2-3 cm-1 and variations close to 60% in intensity have been
observed.
The present results have been obtained with a He-Ne red laser (633 nm.). Future experimental results
will be carried out analyzing other natural ultramarines and, on the other hand, using another laser (Ar
green laser, 514 nm.) in order to extract more conclusions about the possible spectral differentiation
proposed here.
Acknowledgements
This work has been supported by the Spanish Government project (CICYT, TEC 2009-07855), entitled
‘Investigation and Optimization of Raman Spectroscopy Applied to the Direct Analysis of the Cultural
Heritage.’
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Raman monitoring of the polymerization reaction
of a hybrid protective for wood and paper
Laura Bergamonti,1 Claudia Graiff,1 Clelia Isca,1 Giovanni Predieri,1
Danilo Bersani,2 Pier Paolo Lottici2*
Chemistry Department, University, Parma, Italy, +39 0521 905430,
[email protected]
2
Physics and Earth Sciences Department, Parma, Italy, +39 0521 905238, [email protected]
1
The cellulosic materials (wood and paper) but also stone materials, exposed outdoors or in high humidity
conditions, are subject to various forms of degradation, including the biological deterioration caused by
various microorganisms such as bacteria, fungi and algae.
Here we present a monitoring by micro-Raman spectroscopy of the polymerization reaction of a new
polymer for the protection of materials of interest for cultural heritage, in particular for lignocellulose.
The polymer is a hybrid organic-inorganic polyamidoamine (PAA) functionalized with hydrophilic and
siloxanic groups.
The polyamidoamines are polymers characterized by the presence of amide and tertiary amino groups,
obtained by polyaddition of bis-acrylamides with primary and secondary mono/ di- amines in protic
polar solvents. The mechanism of addition of the amine to the acrylamide double bond is a nucleophilic
addition 1-4 to the α, β unsaturated carbonyl compound.
To monitor the progress of the reaction of polymerization with Raman spectroscopy, we have followed
the decrease of the intensity of the C=C bond stretching vibration peak at 1629 cm-1 of bis-acrylamide,
which should disappear when the polymerization reaction is complete, with respect to the peak intensity
of the carbonyl group stretching mode at ≈ 1650 cm-1.
To optimize the reaction conditions between the bis-acrylamide and the primary amine, with and
without siloxanic functionality, molar ratio of the reactants, type of solvent (water, methanol, ethanol),
order of mixing of the reactants (amine, amide), reaction temperature (25 °C, 55 °C, 93 °C) have been
varied.
Raman spectra indicate that the most favorable conditions are obtained when the solutions are
concentrated, when methanol is used as solvent and when bis-acrylamide is added dropwise to the
solution containing the primary amine.
The proposed polymer is being tested as a useful tool for the protection of wood or paper artifacts of
interest for Cultural Heritage conservation.
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Reference Raman data of the artist palette – tool for in-situ
investigation of J. Matejko (1838-1893) paintings
Iwona Żmuda-Trzebiatowska,1* Mirosław Wachowiak,2* Mirosław Sawczak,1
Gerard Śliwiński1
Photophysics Dept., The Szewalski Institute, Polish Academy of Sciences, Gdańsk, Poland,
2
Dept. of Conservation and Restoration of Modern and Contemporary Art, N. Copernicus University,
Toruń, Poland
1
During last two decades the studies performed with the usage of Raman technique on historical objects,
materials and also on artist’s techniques and production technologies of the past result in elaboration
of reliable analytical procedures. Depending on the analyzed material and information of interest the
Raman data are often complemented by additional examinations of the elemental and/or compound
composition and structure. Such an approach is well proven in the research on historical materials and
a variety of combinations of the Raman spectroscopy with other techniques is reported.[1] This also
ensures marked improvement of the confidence level of the results.
In the analysis of results the reference spectra accessible in the form of databases play an important
role. These data enable identification and discrimination of substances using the unique characteristics
of the Raman spectrum of a given material. It can be observed, that the need for dedicated spectral
data results in works devoted to specific historical objects, collections, materials and model materials.
In particular, the Raman identification and reference spectra of historical paints represent an area of
continuous research progress.[2] However, literature data indicate that most of the Raman studies on
pigments are devoted to identification and characterization of materials used in ancient artworks. Only
few published works are dealing with modern paintworks from the period of XIX-XX c. performed with
the use of newly synthesized organic and inorganic materials in addition to the traditional ones. For
example, recent results of the study on crystalline phases of the blue dye copper phtalocyanine indicate
on dating possibility.[3] In the work of Casadio et al the presence of synthetic pigments in modern
paintings is concluded from the comparative Raman analysis performed with the use of the reference
cobalt-based green and blue pigments.[4] Studies published so far, confirm that reliable identification
and characterization of recent paint materials are needed and the research on paint components and
compositions can be effectively performed by the Raman study combined with other complementary
techniques.
The objective of this work is to provide tool enabling non-destructive, in-situ investigation of the
paintings collection of J. Matejko (1838-1893). It bases on the assumption that reliable identification
of the historical paint materials can be obtained by comparative analysis of spectra from dedicated
database with these obtained non-invasively from the original paintings. In order to create the spectral
database the detailed analysis of the mix of original paint material preserved from the period of 18801893 and stored in the National Museum in Cracow is performed. The Raman spectra of the paints
of J. Matejko are treated as the key spectroscopic signatures and are complemented by additional
measurements using techniques such as XRF, XRD, FTIR and NIR, selected in dependence on the
kind of materials (pigments, fillers, organic dye carriers, etc). Data from elemental analysis are used for
identification of pigments such as: ochre, cerulean blue, cobalt blue, emerald green, vermillion, chrome
yellow and strontium yellow and the presence of ultramarine and malachite in the paint material and
also admixtures of the bees wax to medium are revealed in agreement with Raman spectra. For paints
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containing organic dye and also for binders the FTIR measurements are performed, too. So the usage
of individual pigments as well as pigment mixtures provided by producers is confirmed. From the
presence of characteristic trace elements the origin and production methods of the paint components
are concluded. New information on fillers, dye carriers (Al or Sn compounds) and the binding media
are obtained. Results obtained so far contribute significantly to the knowledge on the workshop of
the XIX c. artist. Moreover, it is confirmed in agreement with literature that the approach based on
the use of dedicated Raman reference data complemented by results obtained by other appropriate
spectroscopic techniques enables non-destructive, precise identification of the original paint materials.
Acknowledgements
This work has been financially supported by the DS research grant 030295 from the Faculty of
Mechanical Engineering, Gdańsk University of Technology and via project ’19 century pigments’
2012/05/D/HS2/03385 of the NCN -National Science Centre of Poland.
References
[1] L. Burgio, R. J. H. Clark, Spectrochimica Acta Part A, 2001, 57, 1491–1521.
[2] F. Rosi, J. Raman Spectrosc. 2004, 35, 610–615.
[3] C. Defeyt, J. Raman Spectrosc. 2012, 43, 1772.
[4] F. Casadio, et al., J. Raman Spectrosc. 2012, 43, 1761.
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Spectroscopic characterization of the Illuminated Manueline
Charters of Marvão and Lousã
Cristina Barrocas Dias,1* Ana Claro,1 Sara Valadas,1 Lília Esteves,2 Maria José
Mexia,3 Jorge Oliveira,4 Teresa Ferreira,1 António Candeias1,2
HERCULES Laboratory, Évora University, Portugal, 351 266745300, [email protected]
[email protected], [email protected], [email protected]; [email protected]
2
José de Figueiredo Laboratory, Rua da s janelas Verdes, Lisbon, Portugal
3
Torre do Tombo National Archive, Alameda da Universidade, Lisbon, Portugal
3
History Department/ Évora University, 351 266745300, [email protected]
1
King D. Manuel I of Portugal in the beginning of the 16th century updated the public life regulation of
the realm, renovating the town and villages foral charters which had been issued in the 12th century. The
updated codices were written on parchment in contemporary language with gothic style characters, and
the folios Incipit illuminated with precious ornaments. These new documents expressed the authority
of the realm, and sometimes, also reflected the importance of the village or town.
Previous studies on the Manuelin charters of Vila Flor [1] and Sintra [2] have shown that different
materials have been used for their production.
The study presented here involves the material analysis of the Marvão and Lousã Charters. These two
villages had different historical importance in the 16th century: while Marvão administered a vast
and strategic geographic area, Lousã was a smaller village located close to Coimbra, which was the
main administrative centre of the region. Maybe due to their difference in terms of administrative
importance, the codices of Marvão and Lousã have a different typology of the illuminated folios Incipit.
The Marvão Charter presents a shield crowned with the royal arms flanked by two armillary spheres,
with the name Dom Manuel painted bellow in a banner and a large border in the lower part of the page
painted with white carnations. The Lousã presents a more sober decoration with a gilded initial D and
a decorative vegetative border with red and blue flowers (version A); a second copy of the Lousã charter
(version B), with a similar decoration, was also available and subject to study. This version B of the
Lousã Charter was in poor conservation state when compared to the version A of the document.
Micro sampling was performed with a micro chisel of the different colours of the folios Incipit of Marvão
and the two copies of the Lousã Charters. The size of the micro samples was around 100 micrometers.
The samples were subjected to various analytical techniques namely, micro-Raman, micro-FTIR, SEMEDS and HPLC-DAD in order to identify the pigments and the binding media used in their making.
A large number of different pigments could be identified in the Marvão compared to the Lousã Charters.
In both Marvão and version A of Lousã Charters, analysis enabled the identification of azurite and
malachite in the blue and green areas. Lighter hues were obtained with the addition of lead white, while
carbon black was added to obtain darker hues. Red colours were obtained mainly with vermillion, but
in several reddish areas, brazilwood lakes could be identified by HPLC-DAD.
Silver dust was added to the paint used in the bluish background of the armillary spheres of the Marvão
Charter and in some silvered areas of the version A of Lousã Charter, while gold dust was also found in
some painted areas of both documents.
The yellows, identified only in the Marvão Charter, were obtained with massicot, lead-tin yellow Type
I and II and ochre.
Both polysaccharides and proteins were identified as binders in different colours and calcium carbonate
was detected in some cases as extender. Carbon black and iron gall ink was used for the writing.
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Surprisingly, the analysis of the samples collected in the version B of the Lousã Charter revealed the
use of some pigments that could not be found in the 16th century. For example the blue colours were
obtained with azurite and ultramarine blue (likely synthetic); green was obtained with prussian blue
and a non-identified yellow pigment. In the golden areas, brass powder was used instead of gold powder
and in the areas where silver powder had been used in version A, a tin alloy powder was used to make
the paint used in version B.
The results obtained indicate that the materials used to make the Marvão Charter and version A of the
Lousã Charter are consistent with their production on the 16th century and some have already been
described in previously analysed charters. The version B of the Lousã Charter was probably restored
in the XIX century because the parchment and some of the materials used are similar to that of the
version A. It is known that more than one copy was made in the 16th century, but in most cases only one
copy survived. The version B of the Lousã Charter is most likely the copy that was handled on a regular
basis, leading to deterioration of the manuscript and its restoration in the 19th century.
References
[1] L. Moura, M. J. Melo, C. Casanova, A. Claro, “A study on Portuguese manuscript illumination: The Charter
of Vila Flor (Flower town), 1512”, J. Cultural Heritage. 2007, 8, 299–306.
[2] M. Manso, A. Le Gac, S. Longelin, S. Pessanha, J. C. Frade, M. Guerra, A. E. Candeias, M. L. Carvalho,
“Spectroscopic Characterization of a Masterpiece: The Manueline Foral Charter of Sintra”, Spectrochimica
Acta Part A. 2013, 105, 286–296.
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Materials and gilding techniques on plasterwork in the Alhambra
(Granada, Spain)
Ana Domínguez Vidal,1* María José de la Torre López,2 Domene Ramón Rubio,3
María José Campos Suñol,4 Ulrich Schade,5 María José Ayora-Cañada1
Department of Physical and Analytical Chemistry, University of Jaén, Spain,
2
Department of Geology, University of Jaén, Spain, [email protected]
3
Conservation Department, Council of The Alhambra and Generalife, Granada, Spain,
[email protected]
4
OTRI, University of Jaén, Spain, [email protected]
5
Infrared beamline IRIS, BESSY – II Helmholtz-Zentrum Berlin für Materialien und Energie GmbH,
Berlin, Germany, [email protected]
1
A complete study of the decayed gilded decorations of the stalactite vaults of the Hall of the Kings in the
Nasrid Palace of the Lions in the Alhambra complex (Granada, Spain) has been carried out. A combination
of analytical techniques capable of elemental, microstructural and molecular characterisation was used
for the identification of ancient gilding technology.
Sampling was performed on the remnants of golden decorations in the seven vaults of the Hall of
the Kings. The samples were analysed in order to characterize both the substrate and the finishing
layers: traces of gilding showing golden, black and yellow-orange areas as well as areas of violet tonality
that according to their spatial disposition seem to have been golden before. The analytical techniques
employed were petrographic microscopy, Raman micro-spectroscopy, FTIR micro-spectroscopy and
scanning electron microscopy with energy-dispersive X-ray spectrometry (FESEM-EDX).
Raman spectra for raw samples (without any sample preparation) and thin cross sections were
recorded on a Renishaw (in Via Reflex) spectrometer coupled to a Leika microscope. FTIR spectra
were obtained with a Nicolet spectrophotometer coupled to a Nicolet Continum IR microscope using
either the conventional IR source or synchrotron radiation. In both cases FTIR transmission spectra
were collected from the samples placed on a diamond cell viewed through the microscope system.
Micrometric samples were first placed and pressed in the diamond cell, and then only one window of
the cell was used for the measurement. A Zeiss SUPRA40VP and LEO 1430-VP were used to obtain
images in both secondary electron (SE) and backscattered electron (BSE) modes. The use of variable
pressure enabled the investigation of non-conductive specimens in their natural uncoated state. In this
way, the samples can be investigated by other spectroscopic techniques.
Three different techniques of gilding and false gilding have been characterized: a) application of a very
thin gold leaf (1-2 µm) using a proteinaceous binder to fix the gold leaf directly to the finishing layer of
the plasterwork substrate (Figure 1a), b) false gilding using a thicker tin leaf (10-13 µm) tinted to look
like gold by means of a varnish based on a natural resin (Figure 1a), and c) gilded tin which consist of
a laminated structure with a thin layer of gold (1 µm) over a thicker tin layer (10-13 µm). (Figure 1b).
Tin layers appeared very altered in some areas showing an expansion in volume (see figures 1a and
1b) leading to thickness about 50 µm. In these areas Raman spectroscopy clearly identified SnO with
bands at 113 and 203 cm-1. In addition, other alteration products like calcium oxalates have been
detected, possibly as a result of the degradation of organic materials. The intense fluorescence from the
organic layers made impossible the recording of any useful Raman spectrum. Organic materials were
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successfully identified by means of FTIR.
In conclusion, the present study highlights the importance of the use of multi-analytical approaches in
the cultural heritage field and in particular, for the identification of ancient gilding technology. SEMEDX analysis provided the base knowledge of the metal leafs and their spatial disposition; μFTIR
spectroscopy was prevalently used to examine the composition of the organic materials employed as
adhesive and varnish and Raman microspectroscopy provided insight into the different degradation
compounds formed.
Acknowledgements
This work was financed by the research project CTQ2009-09555 from the Ministry of Science and
Innovation. The Council of the Alhambra and Generalife, PAIDI Research Groups FQM 363 and RMN
325 are also acknowledged for supporting this project.
The Helmholtz-Zentrum Berlin für Materialien und Energie is thanked for beamtime and travel
expenses assigned to proposal 2012_120151.
Figure 1. SEM-BSE (backscattered electron mode) images of thin cross sections showing a.) a sequence of
layers from bottom to top: gold, altered tin, organic layer, and gold layer and b.) from left to right: two laminated
structures formed by a thick tin layer covered by a thin layer of gold and a final gypsum layer applied to cover the
altered gilded decoration which macroscopically looks violet.
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Characterization of gypsum and anhydrite ground layers from 15th
and 16th century Portuguese painting by Raman Spectroscopy,
Micro X-ray diffraction and SEM-EDS
Vanessa Antunes,1* António Candeias,2,4 ,Stéphane Longelin,3 Ana Isabel
Seruya,3 Maria Luísa Carvalho,3Maria José Oliveira,2 João Coroado,5
Luís Dias,4 Vitor Serrão1
Instituto História da Arte da Faculdade de Letras da Universidade de Lisboa (IHA-FLUL),
Alameda da Universidade, Lisboa, Portugal,[email protected],[email protected]
2
Laboratório José de Figueiredo da Direcção-Geral do Património Cultural (LJF-DGPC), Lisboa,
Portugal, [email protected], [email protected]
3
Centro de Física Atómica da Universidade de Lisboa (CFA-FCUL), Lisboa, Portugal,
4
Centro HERCULES, Universidade de Évora, Portugal, [email protected]
5
Instituto Politécnico de Tomar (IPT), Tomar, Portugal, [email protected]
1
This work intends to characterize the execution techniques of Portuguese painting ground layers from
15th and 16th centuries (1450-1600), taking into consideration the chosen materials, its composition,
manufacturing processes, application, polishing, under-drawing and priming. The use of gypsum in
these layers is common in the Iberian Peninsula, either as natural resource, either as evidence on
Portuguese and Spanish paintings1, prepared generally from calcium sulphate and animal glue. Besides
the common elements from the various painting workshops at the time, gypsum and anhydrite ground
layers have specificities that allow characterizing different compounds.
The clarification of the specific methodologies and materials used in each workshop can be related with
the contemporary treatises. The analysis and interpretation of ground layer techniques is commonly the
result of several incomplete instructions brought by different treatises,such as several authors suggest
2-7
. The few Portuguese treatises and manuscripts describing the process of gypsum transformation
and preparation for ground layers in painting started to be written in 17 th century8-10. Based in this
complementary information, although those treatises mention the same animal glue binder, differences
on the choice of the type of filler material can be defined, between regional or cosmopolitan workshop,
and perhaps the influences of the geographical conditions. We may isolate and define those differences
and similarities through a chemical, geographical and geological approach of ground layers that
constitute the paintings Workshop of Viseu, Coimbra, Lisboa and Évora. By standardizing the ground
layers for each painting workshop, we will try to find scientific confirmation for the identification and
origin of the paintings, as announced by Art History.
Experimental procedure
Cross-sections were prepared and examined initially by optical microscopy and SEM imaging (SE
and BSE modes), to identify different layers of gypsum and anhydrite, the number of ground and paint
layers, granullometry, layer thickness, polishing between layers, priming, etc. Micro-samples were
observed with a Leitz Wetzlar optical microscope coupled with digital camera Leica DC 500equipped
with visible light, dark and light field.
To identify elemental composition of the inorganic compounds a SEM-EDS Hitachi 3700N scanning
electron microscope coupled with a Bruker XFlash 5010 SDD detector. The current used was 20 kV. In
gypsum and anhydrite ground layers Ca and S were identified as major constituents and trace elements
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such as Sr, Al, K, Fe, Mg, Si, P and Na were also detected. Strontium might be associated to celestite in
calcium sulphate while Al, K, Fe, Si, P and Na can be related to aluminosilicates and Mg, Ca and Fe to
dolomite.
Micro-Xray diffraction was performed by a commercial Bruker AXS D8 Discovery diffractometer
with Cu K radiation, Gadds detector, angular range8–70º and a step of 0.02º. The EVA software was
used for the identification of the phases. From these results it was possible to determine the relative
percentage of gypsum and anhydrite in the studied ground layers. However, it was not detected any
compound associated to the elements Mg and Fe, identified by EDS as trace elements, probably because
they arepresent in quantities lower than the detection limit of the equipment.
The Raman spectra were measured on a Raman spectrometer Horiba Xplora Confocal Micro-Raman,
using a laser diode source operating at a wavelength of 785 nm. The laser power applied to the sample
was 2-5 mW. Each spectra for typical times of 2 s with 50 scans using a diffraction grating of 1200 lines/
mm that gives a resolution of 4 cm-1. Pictures have been taken with a BX41 microscope (Olympus) using
x100 magnification and equipped with a Ueye 1640 camera. Measurements confirmed the existence of
anhydrite and gypsum. Furthermore the compounds containing the trace elements already detected
by SEM(EDS) were also identified : silicate minerals of calcite (CaCO3), dolomite (CaCO3.MgCO3) with
Feand sulfate mineral celestite (SrSO4).This last compound, existing in very low levels in gypsum and
anhydrite ground layers, occurredin two different ways: whether as celestite grains or celestite grains
covered with lead.
Conclusions
This preliminary study allows us to make a first comparison between different Portuguese workshops
based on the celestite and dolomite patterns, even though the painters of the last decade of the 16th
century worked in various regions of Portugal.It is our purpose compare the obtained results with
treatises and specialized bibliography and define the Portuguese integration in the peninsular context
at the time, looking to set national and peninsular patterns.
Acknowledgements
The authors wish to acknowledge the Fundação para a Ciência e Tecnologia (FCT/MCTES - PIDDAC) for
financial support (PhD grant SFRH / BD / 37929 / 2007 , science andtechnology grant SFRH / BGCT
/ 51652 / 2011 and project PTDC/EAT-HAT/100868/2008) trough the program Ciência e Inovação
POCI2010 and QREN-POPH – typology 4.1 (co-participated by the European Social Fund (ESF) and
national funds MCTES), as well as the institutions IHA-FLUL, LJF-DGPC, IPT, HERCVLES Lab.Évora and CFA-FCUL.
References
[1] S. S. Gómez et al., Contribution to the study of grounds for panel painting of the Spanish School in
the fifteenth and sixteenth centuries. in Painting techniques, history, materials and studio practice,
contributions to the Dublin Congress, 7-11 September 1998 London, International Institute for
Conservation of Historic and Artistic Works, 1998.
[2] L. Carlyle et al., Historically accurate ground reconstructions for oil paintings, in Preparation for
Paintings, The Artist’s Choice and Its Consequences J.H. Townsend, et al., Editors. Archetype Books,
2008, p. 110–122.
[3] L. Carlyle, M. Witlox, Historically Accurate Reconstructions of Artists’ Oil Painting Materials. Tate’s
Online Research Journal, Tate Papers ©, 2007.
[4] P. Hendy, A. S. Lucas, The ground in pictures. Museum, 1968, XXI(4), p. 245–276.
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[5] S. Santos Gómez, Las preparaciones de yeso en la pintura sobre tabla de la Escuela Española, D. d. P.
Facultad de Bellas Artes, Editor. Universidad Complutense de Madrid, Servicio de Publicaciones, Madrid,
2006.
[6] M. J. Gonzalez Lopez, Estudio de las preparaciones de pintura sobre soportes de tela y tabla,
Caracterizacion de sus principales componentes, comportamiento y factores de deterioro, in Bellas Artes,
Universidad de Sevilla: Sevilla, 1992, p. 792.
[7] S. S. Gómez, M. S. A. Moya, and A. Rodriguez, Reconstruction of documented preparation methods
for gesso grosso and gesso sottile in Spanish School panel paintings in Art Technology – Sources and
Methods, S. Kroustallis, et al., Editors. Archetype Publications: London, 2008, p. 196.
[8] P. Nunes, Arte da Pintura, Symmetria e Perspectiva, in fac-simile da edição de 1615 com um estudo
introdutório de Leontina Ventura, 1982, L. Ventura, Editor. Editorial Paisagem: Porto, 1982.
[9] F. De Holanda, Da pintura antiga, introd. notas e comentários de José da Felicidade Alves, J.d.F. Alves,
Editor, Livros Horizonte: Lisboa, 1984, p. 128.
[10]P. Monteiro, L. Afonso, Fontes para o estudo dos pigmentos na tratadística portuguesa,da Idade Média a
1850, in Artis, revista do Instituto de História da Arte da Faculdade de Letras da Universidade de Lisboa,
Instituto de História da Arte da Faculdade de Letras da Universidade de Lisboa, Lisboa, 2007, p. 161–186.
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Identification of deteriorated pigments on wall paintings from
Lutrovska klet, Sevnica, Slovenia, using Raman spectroscopy and
SEM-EDS
Katja Kavkler,1* Ajda Mladenovič,1 Ana Mladenovič2
Restoration Centre, Conservation Centre, Institute for the Protection of the Cultural Heritage of
Slovenia, Ljubljana, +386 1 2343 168, [email protected]
2
Slovenian National Building and Civil Engineering Institute, Ljubljana, Slovenia,
[email protected]
1
In 2010 conservation and restoration works were started on a renaissance wall painting in Lutrovska klet
(cellar) at Sevnica Castle, in Slovenia. On the east side of its interior, the ground floor of the outbuilding,
which served as an oratory for Lutherans during the Reformation, is completely painted. The painting
was done in secco (tempera) technique and has severely deteriorated due to environmental factors.
The causes for its present condition are the following: high relative humidity, salt crystallization,
temperature fluctuations, and improper use of the room in the past, when it served as a wine cellar and
warehouse. Unfortunately, past restoration interventions have caused additional problems, especially
due the inappropriate choice of consolidants. Loss of strength of the binder has led to pulverization and
flaking of the paint layers, so that a large part of the original layers has been lost. Part of the painting
was covered by a greyish veil of gypsum, and microorganisms could be observed as black stains on the
walls. Advanced analysis methods were of great importance in the resolving of these problems.
Several samples were taken from the wall painting, from the non-affected as well as from deteriorated
areas. The samples were embedded in polyester resin and polished. Cross sections were observed
using an Olympus BX60 optical microscope, as well as in a micro-Raman spectrometer and scanning
electron microscope, equipped with energy dispersive spectrometer (SEM-EDS). In the case of Raman
and SEM-EDS, point as well as mapping analyses were performed.
Raman spectra were obtained using a Horiba Jobin-Yvon LabRam HR800 spectrometer, equipped
with a high-stability BX 40 optical microscope, a grating with 600 grooves per mm, and an air-cooled
CCD detector. The spectrometer was set up in confocal mode. Spectra were excited with a 785 nm laser.
A low vacuum LV-SEM (JEOL) 5500 LV scanning electron microscope with an OXFORD EDS analyzer
was used for mictrostructural and elemental analysis.
Samples from paint layers were taken in different areas – deteriorated as well as non-deteriorated.
Wherever possible both samples were taken from the same paint in order to compare differences
between unchanged and deteriorated pigments. For the present study four cases were selected – green,
blue, light brown and red painting areas. Pigments were identified using point mode micro-Raman
spectroscopy. The results showed that in the case of the blue paint layers, smalt and calcite were used
as pigments, whereas malachite mixed with lead white, yellow ochre, lead red and calcite was used for
the green layers, lead white mixed with lead red, yellow ochre, calcite and probably some organic dyes
for the brown layers, and, for the red paint layers, red lead and lead white in the upper layers, whereas
vermilion was identified was identified in the lower layers.
Further analyses showed that the microstructure and chemical composition of several pigments used
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in the analysed painting had been changed. The main reasons for deterioration were the presence of
moisture and sulphur compounds in the air, the presence of microorganisms, and the properties of
certain less stable pigments.
In the smalt, migration of K+ ions was observed by SEM-EDS mapping, which caused discolouration[1],
and by optical microscopy. The malachite changed into copper sulphate and copper oxalate, both of
which are green in colour and therefore do not change the visual appearance of the painting[2][3]. The
colour was not altered by transformation from basic lead carbonate to lead sulphate, both of which are
white in colour. On the other hand, lead sulphide, which is a more highly deteriorated product of lead
carbonate, is black, and could be observed by optical microscopy and identified in the white layers by
Raman spectroscopy[4]. The most visible change in the appearance of the wall painting was a greyish
veil over the paint layers. This was the result of changes from calcium carbonate to calcium sulphate.
The latter is a soluble salt, which crystallizes on the painting surface, as observed with both SEMEDS and Raman mapping. The black crusts observed in some areas of the painting are caused by the
inclusion of dark dust particles into the calcium sulphate matrix.
Scanning electron microscopy with energy dispersive spectrometry and micro-Raman spectroscopy
proved to be useful methods for the classification of the deterioration of pigments and determination
of causes for visible changes in paintings. Combining point and mapping analyses provides more
information compared to a single method.
References
[1] M. Spring, C. Higgit, D. Saunders, Nat. Gall. Tech. Bull. 2005, 26, 56.
[2] K. Castro, A. Sarimento, I. Martínez-Arkarazo, J. M. Madaraiga, L.A. Fernández, Anal. Chem. 2008, 80,
4103.
[3] S. Švarcová, D. Hradil, J. Hradilová, E. Kočí, P. Bezdička, Anal. Bioanal. Chem. 2009, 395, 2037.
[4] G. D. Smith, L. Burgio, S. Firth, R. J. H. Clark, Anal. Chim. Acta. 2001, 440, 185.
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Characterization of Middle Age mural paintings: in-situ Raman
spectroscopy supported by different techniques
Marco Veneranda,1 Mireia Irazola,1 Marta Díez,1 Ane Iturregui,1
Julene Aramendia,1* Kepa Castro,1 Juan Manuel Madariaga1
1
Dept. Analytical Chemistry, University of the Basque Country (UPV/EHU), Bilbao, Spain,
The conservation of wall paintings is closely related with the action of external agents. For example, the
water present in the soil can ascend through the walls of a building by capillarity. These infiltrations
imply the presence of dissolved salts which under certain conditions can give rise to white efflorescences.
[1]
These efflorescences cause mechanical stress, chemical alterations and, finally, aesthetical problems.
[2]
Specially in the past, through conservative interventions these problems were generally hidden under
new painted layers. In this sense, degradation processes and repaints become the main causes of the
wall paintings´ original essence lost.
In this work several wall paintings from two different churches in Alava (Basque Country, Spain)
were analysed: one from the 14th century located in “La Asunción” Church (Alaiza) and the other one
from the 15-16th century located in “San Esteban de Ribera” (Valderejo). The molecular and elemental
analyses carried out in this study try to survey the original materials used by the artists, to identify the
pigments used in ulterior repaints and to classify the main products formed due to the different sources
of deterioration.
For this aim, several analyses were carried out: portables Raman and EDXRF spectrometers were used
in situ in order to obtain a first screening of the composition and the conservation state of the wall
painting and at the same time, to identify the most interesting areas for sampling. The EDXRF device
allowed evaluating the elemental composition of mural paintings, supporting in this way the Raman
data. The laboratory analysis of the collected samples was carried out with ionic chromatography
which enabled a more exhaustive characterization of the specimens and, thus, a more comprehensive
diagnosis of the affection.
The ultra mobile B&WTEK InnoRam spectrometer used for in situ analyses is provided with a 785
nm excitation laser and a Peltier cooled CCD detector. At first the spectra were acquired at lower laser
power, and then it was increased until a good signal-to-noise ratio was obtained but avoiding the
thermo-decomposition. To support the Raman data a hand-held EDXRF portable analyzer XMET5100
(OXFORD Instruments) with a high resolution silicon drift detector was employed. For the laboratory
analysis a Dionex ICS 2500 ionic chromatograph with a suppressed conductivity detector ED50 was
used.
Regarding to Alaiza church, the wall paintings were partially repainted in order to repair decayed areas.
As original components, hematite (Fe2O3) and black charcoal were identified by Raman spectroscopy.
The intonaco was composed by calcite (CaCO3) and gypsum (CaSO4). In the repainted areas ultramarine
blue (Na8-10Al6Si6O24S2-4) and rutile (TiO2) were determined as pigments, in conjunction with barium
sulphate, which started to be used in the 19th as a filling material. X-rays fluorescence was successfully
used to support Raman analysis in the characterization of several pigments such as chrome yellow
(PbCrO4) and vanadinite (Pb(VO4)3).
Several degradation products such as nitrates (KNO3 and Ca(NO3)2·4H2O) were identified by in situ
Raman spectroscopy. By means of ionic chromatography high correlations between chloride and
sodium, sulphate and strontium and nitrate and sodium were detected.
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Concerning the church of Ribera, the original used pigments were: vermilion (HgS), hematite (Fe2O3),
black charcoal, orpiment (As2S3) and lead white ((PbCO3)2×Pb(OH)2). The wall paintings were also
partially repainted on the green and yellow areas. In the green colour only phtalocyanine green was
found, and in the yellow one, a synthetic yellow belonging to the disazo family was identified; both from
the 19th century.
It must be highlighted the usefulness of the Raman spectroscopy in the analysis of wall paintings. Apart
from the identification of the artworks’ constitutive materials, the main degradations compounds were
detected, providing useful data for future restoration projects.
Acknowledgements
This work has been financially supported by the CTP (2012-P10) project from the Pirineos work area
(Basque Government). M.Veneranda is grateful to the Spanish Ministry of Economy and Competitiveness
(MINECO), J. Aramendia and A. Iturregui to the Basque Government and M. Irazola to the Basque
Country University for their grants. Authors thanks to Diputaciòn Foral de Alava for all their support.
Figure 1. Raman spectra from Alaiza wall painting, showing the presence of
vanadinite, chrome yellow, barium sulphate, gypsum and calcite.
References
[1] H. Brocken, G.T. Nijland, Construction and Building Materials, 2004, 18, 315-323.
[2] M. Irazola, M. Olivares, K. Catro, M. Maguregui, I. Martínez-Arkarazo, M.J. Madariaga, J.Raman
Spectrosc. 2012, 43, 1676-1684.
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Raman microspectroscopic identification of pigments of newly
discovered gothic wall paintings from the Dominican Monastery in
Ptuj (Slovenia)
Maja Gutman,1* Sabina Kramar,2 Ajda Mladenovič,1 Vlasta Čobal Sedmak,1
Martina Lesar Kikelj1
Restoration Centre, Conservation Centre, Institute for the Protection of the Cultural heritage of
Slovenia, Ljubljana, Slovenia, +386 1 2343 118, [email protected], [email protected],
2
Slovenian National Building and Civil Engineering Institute, Ljubljana, Slovenia,
[email protected]
1
In September 2012, during the first reconstruction phase of the Dominican Monastery in Ptuj, precious
gothic wall paintings were discovered; a significant find that will greatly contribute to our understanding
of artistic and architectural history of the complex. The paintings are located on the south wall of the
former sacristy, adjacent to the Chapter house.
The uncovered murals attract attention with their colouring and very interesting figural compositions,
depicting a row of horse riders turning towards one another. Particularly intriguing is also the
pronounced blue and orange-red pigment, which - together with stylistic features of individual figures
- serves as an orientation for dating to perhaps the early 14th century.[1] The depicted procession of
riders suggests either the images of certain saintly legends or even a scene of the Magi. Due to the bad
condition of the wall paintings, a fairly thick layer of calcium carbonate on the surface and especially
because of the complex process of stabilization of the paint layer, it is necessary to proceed with the
conservation-restoration works. The colour combinations used along with the determination of the
pigments and painting technique as well as distinctive details such as costume, decorative motifs and
architectural elements can assist in clarifying the subject matter and dating.
This study presents the application of Raman micro-spectroscopy for the analysis of pigments from
newly discovered wall paintings. Several natural as well as synthetic inorganic pigments were identified.
The optical microscope revealed that wall paintings were executed in lime technique, that is mortar
and several layers of lime wash, followed by a layer of paint.
The identified red pigments were red ochre (hematite), red lead (minium) and vermilion (cinnabar), of
which the latter is present in incarnate area, where it is mixed with other pigments, such as red ochre
and carbon black. Our observations also confirmed that the red lead pigment, which was mostly used
for depicting the garments of figures, degraded into a black or brown plattnerite, resulting in darkening
of the red areas.[2]
The blue pigment, which covers the largest area on the wall paintings, was identified as azurite (Figure
1). Despite its relatively high price, azurite was the most important blue pigment in European paintings
throughout the Middle Ages and Renaissance because of its texture and surface quality.[3] Similarly, it
was quite commonly used in mural paintings in Slovenia during the Middle Ages.[4]
We discovered two different yellow pigments: yellow ochre (goethite) for the yellowish horse and leadRAA 2013
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tin yellow type I, mixed together with red lead, used on the orange dress of one of the figures. However,
lead-tin oxide, which was in use between the 13th and the 18th century, was not frequently identified in
Slovenian medieval paintings.[4]
Figure 1. Blue paint layer with azurite, one of the most abundant pigments of the wall
paintings from the Dominican Monastery in Ptuj (Slovenia). a.) Optical microscope,
reflective light. b.) Raman spectrum of azurite (laser 633 nm).
Moreover, two white pigments were also identified; one being lead white (cerussite), applied together
with red lead, and the other being lime white (calcite) on a dress on one of the figures.
The present Raman microspectroscopic study of pigments from the wall paintings of the Dominican
Monastery provides important information on inorganic pigments used in medieval wall paintings in
Slovenia.
Acknowledgements
This research has been financially supported by the Ministry of Education, Science, Culture and Sport
of the Republic of Slovenia, under contract number 3211-05-000545, in the frame of the ConservationRestoration Project ”the Ptuj Dominican monastery.”
References
[1] R. Peskar, Preliminary report on the current progress of conservation-restoration works at the Dominican
monastery in Ptuj/ Preliminarno poročilo o dosedanjem poteku konservatorsko-restavratorskih
del na Dominikanskem samostanu na Ptuju (in Slovene), available on < http://www.zvkds.si/media/
medialibrary/2012/12/Preliminarno_poro%C4%8Dilo_o_dosedanjem_poteku_konservatorskorestavratorskih_del_na_Dominikanskem_samostanu_na_Ptuju.pdf >
[2] D. Saunders, J. Kirby, Gallery technical bulletin. 2004, 25, 62–72.
[3] D. V. Thompson, The materials and techniques of medieval painting. Dover publications Inc.: New York,
1956.
[4] A. Križnar. R. Ruiz Conde, P.J. Sancez-Soto, X-Ray Spectrometry, 2008, 37(4), p. 360–369.
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Shot Noise Reduction through Principal Components Analysis
J. J. González-Vidal, 1,2* R. Pérez-Pueyo,1 M. J. Soneira,1 S. Ruiz-Moreno1
Signal Theory and Communications Department, ETSETB, Universitat Politècnica de Catalunya,
Barcelona, Spain, +34 934016442, [email protected]
2
Institut de Ciències del Cosmos - Universitat de Barcelona, Institut d’Estudis Espacials de Catalunya,
Facultat de Física, Barcelona, Spain, +34 934031327, [email protected]
1
In recent years, the non-destructive technique of Raman spectroscopy has exponentially increased
its application in the art world as it is a suitable technique for the characterization of constituent
pigmentation in art works [1,2]. This task is important for the cataloguing, conservation and restoration
of paintings. In practice, several kind of noises are present in acquired Raman spectra and may
hinder the pigments identification. Thus, background correction and shot noise removal are the most
important operations for the enhancement of the Raman information in experimental spectra [35]
. The aim of this work is to present an algorithm for shot noise reduction with no user input. This
novel approach is based on the chemometric technique of Principal Components Analysis (PCA). The
presented algorithm was proved in a simulation stage and with experimental cases contaminated
with shot noise, obtaining an improved signal-to-noise ratio (see Figure 1). Being fully automated, the
presented denoising solution will be potentially useful for preprocessing unknown spectra as input in
algorithms of spectral identification [6].
Figure 1. Shot noise reduction example: Original spectrum a.)
and denoised spectrum b.).
Acknowledgements
This work has been financially supported by CICYT (TEC 2009-07855), entitled – Investigación y
Optimización de la Espectroscopia Raman aplicada al análisis directo del Patrimonio Artístico, (IRPA).
References
[1]
[2]
[3]
[4]
[5]
J. M. Madariaga, J. Raman Spectrosc. 2010, 41, 1389
H. G. M. Edwards, Spectrochim. Acta Part A. 2011, 80, 14.
M. J. Soneira, R. Pérez-Pueyo, S. Ruiz-Moreno, J. Raman Spectrosc. 2002, 33, 599.
C. J. Rowlands, S. R. Elliott, J. Raman Spectrosc. 2011, 42, 370–376.
E. Kandjani, M. J. Griffin, R. Ramanathan, S. J. Ippolito, S. K. Bhargavab and V. Bansala, J. Raman Spectrosc.,
DOI 10.1002/jrs.4232, 2013.
[6] J. J. González-Vidal, R. Pérez-Pueyo, M. J. Soneira, S. Ruiz-Moreno, J. Raman Spectrosc. 2012, 43, 1707.
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Raman investigation of artificial patinas on recent bronze,
protected by different azole type inhibitors in outdoor environment
Tadeja Kosec,1* Polonca Ropret,2,3
National Building and Civil Engineering Institute, Ljubljana, Slovenia, +386 1 2804547,
[email protected]
2
Conservation Centre, Institute for the Protection of the Cultural Heritage of Slovenia, Ljubljana,
Slovenia, +386 1 23431118, [email protected]
3
1
Bronzes have been widely used for sculptures and other art objects. These artistic bronze objects are
usually found covered by a layer of patina. These layers can either be formed spontaneously during the
years of exposure or they can be artificially applied by using various solutions of inorganic salts. Acid rain
that forms due to the presence of polluting gases may cause extensive damage on the bronze objects and
patina layers. The SO2 and NOx are the main pollutants in urban atmosphere due to the industrial activity
and the emission by automotive vehicles.
It is well known that in humid air, copper and its high copper alloys (bronze) tend to form an oxide layer
(patina). Natural patinas protect copper and its alloys from further corrosion processes. On the other
hand, artists have frequently deliberately patinated bronze for visual effects. Thus, it is of great importance
to study the patina changing mechanism in order to follow its chemical changes and to predict in advance
the likely corrosion processes. Furthermore, the origin of patina and the established degradation state of
bronze works of art is also of a great importance for planning proper conservation treatments for these
objects as well as for establishing the appropriate environmental conditions for their storage and display.
The aim of this study is to investigate the comparison of different protection systems: protection of
patinated bronze by two azole type inhibitors, namely imidazole and benzotriazole. For many years
benzotriazole was used for protection of copper alloys
but due to its toxicity it has to be replaced by some less
toxic compound. In this work inhibiting efficiency of
benzotriazole as a reference and one environment friendly,
newly developed, imidazole based compound were studied.
These corrosion inhibitors were applied in the way that our
practice confirmed the best effectiveness. Inhibited layers
were then protected with a layer that repels water. For the
patinas to study, green chloride and green nitrate patinas,
applied over the brown artist’s patina, were tested, as well as
brown patina and the patina which develops on bare bronze.
The Raman study was applied after chemical patination, at
different exposure periods and after exposing the samples
to outdoor environment for a period of 9 months. At the end
of the 9-month exposure, evaluation of protection efficiency
was investigated and the comparison of the use of the two
different inhibitors is given.
The structures of the patinas and of the corrosion products
were characterized by Raman spectroscopy, scanning Figure 1. Bronze samples: bare and patinated with
electron microscopy (SEM) and X-ray diffraction (XRD). sulphide type patina, nitrate and chloride type patina
The end products of each patina and its protection layer are with the two inhibitor system and additional waxing.
given.
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Micro-Raman Investigation on corrosion of Pb-Based Alloy Replicas
Giorgia Ghiara,1* Serena Campodonico,1,2 Paolo Piccardo,1
Carla Martini,3 Patrick Storme,4 Valeria Bongiorno1
University of Genoa, Dipartimento di Chimica e Chimica Industriale (DCCI), Genova, Italy,
+39 010 3536145, +39 010 3538733, [email protected]
2
INSTM, Genoa
3
University of Bologna, Dipartimento di Ingegneria Industriale (DIN), Bologna, Italy
4
Hogeschool Antwerpen, Royal Academy for Fine Arts, Deparment of Conservation/Restoration of
Metals, Antwerp, Belgium
1
The tendency of a metal to react with the surrounding environment in standard conditions lead to the
formation of different known corrosion products.
Lead is, as other metals, subjected to corrosion yet its effects are less visible due to the formation of a
passivating oxide layer on the metal surface. Lead behavior has been well studied in the past because of
its employment for industrial purposes. Even if general knowledge of pure lead corrosive behavior under
standard conditions - as wet environments - has been achieved, few are the researches that are dealing
with lead and lead alloys behavior under peculiar conditions as presence in the atmosphere of volatile
organic compounds (VOCs)[1] The drastic reactivity of lead alloys to VOCs has widely been recognized
in recent studies of modern art objects in closed spaces characterized by VOCs rich atmospheres[2]
but those researches did not consider the role played by alloying elements in the corrosion process,
accelerating or inhibiting corrosion mechanisms. Up to now no researches have been carried out on
binary and ternary lead alloys considering Antimony and/or Tin as alloying elements.
The employment of microRaman spectroscopy is generally well known for corrosion products of
archaeological and artistic materials. Nevertheless it is often replaced with analysis considered more
suitable for the investigations as qualitative and quantitative elemental analysis (as Energy Dispersive
X-Ray Spectroscopy) or electrochemical analysis (as Open Circuit Potential or potentiodynamic
polarization). It is also true that sometimes all the possible information collected by those non-invasive
techniques needs confirmation that only a specific type of analysis as microRaman spectroscopy can
give.
A study conducted by our research group from University of Genoa and Bologna in collaboration with
the Artesis Conservation Department of Antwerp on original printing letters from the Platin-Moretus
Museum’s Collection consisting of some specific types of Pb-based alloys (with Sb and Sn as alloying
elements), seldom studied in the past has brought to outstanding results in this direction. For the
occasion Pb alloys - in which Tin and Antimony content was conveniently modified - were reproduced
in laboratory and later subjected to specifically created tests following the procedure known as Oddy
Test which allows to test art materials. The experimentation consisted of monitoring of Pb based alloys
exposed to specific organic acids - as formic and acetic acid – vapours in the time span of few days
characterizing corrosion products step by step. Corrosion behaviour was periodically monitored as
specimens showed important changes in morphologies and weight: the embrittlement and increase of
volume with formation of white and black oxidized compounds spawning from the metal were rather
fast representing a serious problem to face once such objects have to be conserved.
On such materials microRaman spectroscopy performed in both Genova and Bologna laboratories
has given a crucial contribution to the ongoing researches proving itself as an innovative technique
not only for the uniqueness of its results and its high detection limits but also for its sensitivity to
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inorganic and organic compounds which in our case were forming on the specimens surface - and were
not recognizable with traditional metallographic analyses or electrochemical techniques. In fact this
powerful but sometimes underestimated tool not only helped us detect all the corrosion products but
allowed us to characterize general corrosion mechanisms affecting this type of alloys giving a wide
variety of information which will help estimating further conservation procedures.
Figure 1. Sample 12 - Sb – rich lead alloy replica
exploded” after Oddy Test
Figure 2. Micro-Raman Spectrum of a sample
showing metallic Sb peaks.
References
[1] L. T. Gibson, C.M. Watt, Corrosion Science. 2010, 52, 172–178.
[2] J. Tétreault, E. Cano, M. van Bommel, D. Scott, M. Dennis, M. G. Barthés-Labrousse, L. Minel, L. Robbiola,
Studies in Conservation. 2004, 48, 237–250.
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OP23
Conservation diagnosis of weathering steel sculptures using a new
Raman quantification imaging approach
Julene Aramendia,1* Leticia Gomez-Nubla,1 Ludovic Bellot-Gurlet,2
Kepa Castro,1 Céline Paris,2 Philippe Colomban,2 Juan Manuel Madariaga1
Department of Analytical Chemistry, University of the Basque Country UPV/EHU, Bilbao, Spain,
2
Laboratoire de Dynamique, Interactions et Réactivité (LADIR) UMR 7075, CNRS and Université
Pierre et Marie Curie, Paris, France
1
Weathering steel is a material used often in contemporary art. The weathering steel was designed to
resist against the atmospheric impact so that no protective coats were needed. In fact, that steel develops
a characteristic rust layer that protects the metal reducing the corrosion rate. This rust layer is formed
by different iron oxyhydroxides that, together with moisture present in the surface, acts as a barrier
that provides the protective ability. The knowledge about the rust layer development is important in
order to propose the most suitable protection or restoration method. Kamimura et al[1] came up with
the labelled as protective ability index (PAI). PAI takes into account the ratio (α/γ) between the mass
of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH), being both main components in the rust layer of
weathering steel. The corrosion rate decreases as ratio (α/γ) increases with the exposition time. This
index could be a tool to diagnose the conservation state of weathering steel structures. In this sense,
the quantification of this index is very useful to assess if some problem of development is being suffered
by steel surface.
Raman spectroscopy, apart from a qualitative technique, recently is becoming a semi quantitative
approach. Therefore, it is a valuable tool for the calculation of the mentioned index in cultural heritage
elements.
In this work, different weathering steel sculptures from Eduardo Chillida were studied. These
artworks are exposed to a Cl- and SO2 rich urban atmosphere in Bilbao, Northern Spain. They present
different aesthetical problems on their surfaces, such as detachments of steel chips, discolorations
and irregularities. In a previous work,[2] a deep atmospheric attack over these surfaces was described.
On the one hand, different atmospheric particles were detected such as calcite, silicates and charcoal
and, on the other hand, some sub products formed by reaction of acid gases and steel components. In
order to identify if the problems in the development of rust layer could be the cause of the problems
on the surface, a semi quantification of different iron oxy-hydroxides was performed over those steel
sculptures.
The semi quantitative work was carried out by the means of micro-Raman spectroscopy imaging. For
this aim, Raman imaging maps were collected using a LabRam HR 800 spectrometer (Horiba Jobin
Yvon). This equipment is provided with a 514 nm emission of Ar+ laser and Peltier cooled CCD detector.
In order to avoid thermodecompositions and mineral phase changes, the laser power was modulated
always adjusting it below 150 µW at the sample. For the mapping under a 100x objective, an Olympus
microscope coupled to the spectrometer and an automatically x-y stage were used.
The data collection was done using LabSpec software (Jobin Yvon Horiba) and the semi quantitative
data was obtained by using a home-made application so-called LADIR-CorATmos (LADIR-CAT)[3]. This
software includes pure spectra profiles (the standards) that are used to fit the experimental spectrum.
The semi quantitative data were used to perform hyperspectral images. These images help us in the
visualisation of how the rust layer is organized, how the different iron oxyhydroxides are disposed
along the steel surface and in the calculation of the PAI images.
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In the analyzed samples the heterogeneity was not very high, but in order to be repetitive, several
Raman images were performed for each sample. Goethite and lepidocrocite were the most commonly
detected mineral phases. However, hematite, akaganeite, magnetite and some atmospheric particles
were also identified. As it can be seen in Figure 1, goethite appeared very concentrated in some specific
areas of the surface, whereas lepidocrocite used to be the main iron oxide phase in the analyzed steel
surface. Obtained maps relate the imaging of sample reactivity, with the PAI values greater than 1 in
the higher areas (low rate of corrosion) while the lower ones show PAI values lower than 1, i.e., location
of high corrosion rate.
Even if these artworks have been exposed outdoors for more than 10 years, results underline that their
rust layers seem to be quite still active.
Figure 1. Semi quantitative results for goethite (α-FeOOH) content in a steel chip sample,
taken from a moderately degraded sculpture.
Acknowledgements
J. Aramendia and L. Gomez-Nubla are grateful to the Basque Government and to the University of
the Basque Country (UPV-EHU) for their pre-doc fellowships. We would like to thank the Bilbao
Guggenheim Museum, the BBVA bank and the Town Hall of Bilbao for all the support during the
analysis of the sculptures. This work has been financially supported by the DEMBUMIES project (ref.
BIA2011-28148), funded by the Spanish Ministry of Economy and Competitiveness.
References
[1] T. Kamimura, S. Hara, H. Miyuki, M. Yamashita, H. Uchida, Corrosion Science. 2006, 48, 2799.
[2] J. Aramendia, L. Gomez-Nubla, K. Castro, I. Martinez-Arkarazo, D. Vega, A. Sanz Lopez de Heredia, A.
Garcia Ibañez de Opakua, J. M. Madariaga, J. of Raman Spectrosc. 2012, 43, 1111.
[3] J. Monnier, L. Bellot-Gurlet, D. Baron, D. Neff, I. Guillot, P. Dillman, J. of Raman Spectrosc. 2011, 42, 773.
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OP24
Raman study of the salts attack in archaeological metallic objects
of the Middle Age: The case of Ereñozar castle (Bizkaia, Spain)
Marco Veneranda,1* Julene Aramendia,1 Silvia Fdez-Ortiz de Vallejuelo,1
Laura García,2 Mikel Neira,3 Kepa Castro,1 Iñaki García,2 Agustín Azkarate,4
Juan Manuel Madariaga1
Dept. Analytical Chemistry, University of the Basque Country (UPV/EHU), Bilbao, Spain,
2
Arkeologi Museoa, Bilbao, Spain
3
QarK Arqueología S.L., Vitoria-Gasteiz, Spain
4
Dept. of Geography, Prehistory and Archaeology University of the Basque Country (UPV/EHU),
Vitoria-Gasteiz, Spain
1
In this work, some metallurgical objects from the excavations of Ereñozar castle ruins (XIII century,
Basque Country, Spain) have been analyzed. The studied collection is formed by a cooper based ring,
ferric and gilded spurs and cooper based decorative objects. The pieces are very heterogenic due to
their original composition as well as to the degradation processes that can be seen on their surfaces. In
fact, the analyses carried out in this study try to determine the mentioned degradation processes. In
the same way, the characterization of the objects tried also to illustrate and explain a historical period,
in the field of metallurgy, that due to the scarcity of the investigations carried out until now, still holds
many questions.[1]
Raman spectroscopy applied in archaeology field has been successfully used to characterise artefacts
as well as to reveal decay compounds degradation causes.[2,3] Deterioration of archaeological metallic
artefacts buried in soil is often associated with the soluble salts present in those soils, which are directly
related to the corrosion products formed or/and deposited on the surfaces of the buried objects. Thus,
the analysis of the corrosion layers has great relevance for the survival of such objects.
Raman spectroscopy was used in order to assess the degradation degree of the analyzed objects. For
this purpose, a Renishaw RA100 and an ultra-mobile B&WTEK InnoRam spectrometer were used,
both provided with a 785 nm excitation laser and a Peltier cooled CCD detector. The spectrometers
were coupled to a microscope (5x, 10x and 50x objectives). The most used objective was the 50x (spot
size around 100 µm) because for this work it was crucial to do microscopic analysis. The laser power
was controlled in order to avoid thermo-decomposition. The ultra-mobile Raman spectrometer was
used in the measures done in the museum. The devices were calibrated daily with a silicon slice using
the 520 cm-1 band. The collected data were treated and interpreted by using Omnic software and homemade databases.[4]
To complete the study, soluble salt tests were done with the soils where archaeological artefacts were
buried. The quantification of the salts was carried out by means of Dionex ICS 2500 ionic chromatograph
with a suppressed conductivity detector ED50 and an Elan 9000 ICP-MS (PerkinElmer), provided with
a Ryton cross-flow nebulizer, a Scott-type double pass spray chamber and standard nickel cones.
The pieces were analyzed before their restoration, thus the ferric ones were still covered by a thick rust
layer composed by different iron oxide phases. It is worth to point out that akaganeite was identify
in all the pieces. This iron oxyhydroxide appears in rich chloride environment. The soluble salts
quantification confirmed the presence of chloride in the soils. The rust layer formed by iron acts as a
protective barrier for the noble metals that are inside the ferric coat. The presence of akaganeite in this
layer could decrease its protective ability because it has a channels structure trough which the water
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infiltrations could arrive to the metal core easier.
Raman analysis also revealed the presence of several degradation products on the surface of the objects,
including, among others, likasite (Cu3NO3(OH)5·2H2O) (figure 1), lead carbonate ((PbCO3)2·Pb(OH)2 )
and Pseudoboleite Pb31Cu24 Cl62 (OH)48.Their presence could be due to the action of soluble salts such as
nitrates, nitrites, carbonates and so on. Nitrate and nitrite were detected by ionic chromatography in
the soils. Likasite was identified in the ring, concretely, in the place where the linker is placed. Finally,
some other salts coming from the soil were detected in the surfaces, such as sodium and magnesium
nitrates.
Figure 1. Raman spectrum of likasite (Cu3NO3(OH)5·2H2O).
Acknowledgements
This work has been financially supported by the CTP2012-P10 project from the Pirineos work area
(Basque Government) and Global Change and Heritage project (UFI11/26) funded by the University of
the Basque Country (UPV/EHU). M. Veneranda and J. Aramendia are grateful to the Spanish Ministry
of Economy and Competitiveness (MINECO) and to the Basque Government for their grants.
References
[1]
[2]
[3]
[4]
T. Trojek, M. Hlozek, Applied Radiation and Isotopes. 2012, 70, 1420–1423.
S. Réguer, P. Dillman, F. Mirambet, Corrosion Science. 2007, 49, 2726–2744.
M. C. Bernard, S. Joiret, Electrochimica Acta. 2009, 54, 5199–5205.
K. Castro, M. Pérez-Alonso, M. D. Rodríguez-Laso, L. A. Fernández, J. M. Madariaga, Analytical and
Bioanalytical Chemistry. 2005, 382, 248.
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Thursday, September 5
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PL3
The Contribution of Archaeometry to Understanding of the Past
Effects and Future Changes in the World Heritage Site of Pompeii
(Italy)
Juan Manuel Madariaga1
1
Country UPV/EHU, Bilbao, Basque Country, Spain, +34 946012707, [email protected]
Archaeometry is now considered a self-standing Scientific Discipline, although just some years ago,
it was considered as a developing field within the Archaeological Sciences. In the first decades of
archaeometric developments, the physical methods were the only applicable, i.e., dating, aerial or
ground-based techniques for surveying new archaeological sites, provenance, etc.). The publication
of the book “Traces of the Past: Unraveling the Secrets of Archaeology Through Chemistry (by J.B.
Lambert, Addison-Wesley, 1997)” encouraged many researchers to apply the knowledge of chemistry
(including analytical methods) to the field of Archaeology, broadening the scope of Archaeometry.
This Plenary Lecture shows the contribution of the new Archaeometric methods (in-situ spectroscopic
analysis, chemometrics, chemical modeling, etc.) to the understanding the past effects and future
(Global) Changes on the conservation of the World Heritage site of Pompeii (Italy).
The results presented in this lecture are part of the published material developed in a research program
that started 6 years ago. Those results were obtained through chemical measurements on small sample
fragments (wall painting, mortars, joint mortars, walls, biofilms on pigmented layer, biofilms on mortars,
efflorescence crystals, etc.) processed at the laboratory level and through the spectral information
obtained in-situ during the three APUV expeditions (Analitica Pompeiana Universitatis Vasconicae)
carried out in 2010 (May), 2011 (September) and 2012 (September). Additionally, samples of volcanic
ashes, lapilli, current and foundational soil were analysed, together with the chemical composition
of rain water sampled in Pompeii, in order to interpret some “extraneous” results encountered when
analysing the composition of the walls and the wall paintings.
Most of the measurements were performed in a non-destructive way. Raman spectroscopy, assisted
by other analytical techniques (Infrared spectroscopy and X-Ray Fluorescence spectrometry, were
used both in-situ (3 portable instruments) and in laboratory, to identify the compounds present in
all the referred samples; in the laboratory also X-Ray Difraction (XRD) and Scanning Electron
Microscopy assisted with Energy Dispersive X-Ray Fluorescence (SEM/EDX) were used to complement
the observations with the other three techniques. Some other measurements were performed in a
destructive way just to obtain the total elemental concentration of the samples (acid digestion followed
by ICP/MS quantification) or to obtain the soluble ions present in the samples (water extraction followed
by ion chromatography).
The most difficult work in the interpretation of the experimental results was to define which are the
original compounds in the walls and wall paintings and which the deterioration compounds promoted
by (a) the chemical changes during the eruption and (b) the reactivity between environmental stressors
(acidic gases, microorganisms, etc.) and the original materials.
This was accomplished by using chemometrics and chemical reactivity simulations through
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thermodynamic modelling, to explain the whole set of compounds identified in a given scenario. In
this methodology, some compounds were tentatively considered as original (calcite for example) that
could react with one or several compounds in the surrounding environment (sulphuric acid aerosol),
resulting in the formation of a stable compound (gypsum in this case) that must be considered as a
deterioration product.
The lecture will show some important case studies conducted during these years of research. The first
one is related with the possibilities, advantages and inconveniences of performing in-situ spectroscopic
analyses on archaeological remains. Differences in the work in open air, compared to the work in a
Museum environment will be presented and discussed. Some results of pigment characterisation,
including the degradation of vermilion and red iron oxide will be presented, including the identification
of the metallic traces accompanying the original minerals used as pigments, it being extremely
important for the correct interpretation of the elemental concentration profiles.
The CO2 attack on non-protected walls will be presented as the greatest decaying phenomenon,
accompanied by rain wash of the highly soluble metal bicarbonate salts formed after the acid attack
(decarbonation of wall paintings and plaster layers till observation of the arriccio mortar). Only calcium,
sodium and potassium carbonate (CaCO3, Na2CO3, K2CO3) were identified by Raman spectroscopy
on such degraded walls, therefore all of them can be considered original compounds in the mortars.
Here appears one of the most exciting questions to be solved in our research: which are the sources
for potassium (and sodium) in the original mortar? Was it included during the process of mortar
manufacturing? Was it included in the walls as a consequence of the materials covering the houses
after the eruption? Our results and our answer explaining such high potassium values will be given.
Additionally, potassium is important because it has been detected (as nitrate and sulphate) in
efflorescence crystals, being one of the most deletorious compounds in the wall painting decay.
Different climate conditions were encountered during such field campaigns, allowing us to consider
also the climatic variable in the analysis of the entire information we have recorded during these years.
This was very important because different types of efflorescence were observed (crystals being two
to five millimetres long) in the same location (wall with or without paintings) during the three years.
Other highly damaging compounds systematically detected were, apart from gypsum (CaSO4.2H2O),
thenardite (Na2SO4), mirabillite (Na2SO4.10H2O), aphthitalite (K 3Na(SO4)2) and syngenite (K2Ca(SO4)2.
H2O), detected in areas near the presence of modern mortars and cements used in past restoration
processes.
Acknowledgements
I would like to thank the researchers U. Knuutinen, M. Maguregui, K. Castro, I. Martinez-Arkarazo, S.
Fdez-Ortiz de Vallejuelo, A. Giakoumaki and A. Pitarch, for their engagement in the projects developed
under the APUV activities, as well as to Dr. A. Tammisto, director of the EPUH expeditions, who
gave us the possibility to access the research area of Insula IX,3. The administrative and technical
facilities given by the Soprintendenza Speciale per I Benni Archeologici di Napoli e Pompei, during our
studies in the Archaeological Site of Pompeii and the National Museum of Archaeology of Naples, is
acknowledged. This work was financially supported by the projects DEMBUMIES (ref.BIA2011-28148,
Spanish MINECO) and Global Change and Heritage (ref. UFI11-26, funded by the UPV-EHU). The
accompanying actions CTQ2010-10810-E (MINECO), AE11-27 (UPV-EHU) and AE12-32 (UPV-EHU)
supported the expeditions APUV2010, APUV2011 and APUV2012, respectively.
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Raman spectroscopy applied to the study of Cretaceous fossils from
Araripe Basin, Northeast of Brazil
Paulo T. C. Freire,1* Francisco E. Sousa-Filho,2João H. Silva,3
Bruno T.O. Abagaro,1 Bartolomeu C. Viana,4 Gilberto D. Saraiva,5 Olga A.
Barros,6 Antonio A.F. Saraiva6
Departamento de Física, Universida de Federal do Ceará, Fortaleza, Brazil,
+55.85.33669906 [email protected]
2
Departamento de Física, Universida de Regional do Cariri, Avenida Leão Sampaio S/N,
Juazeiro do Norte, Brazil
3
Universida de Federal do Ceará – Campus Cariri, Juazeiro do Norte,Brazil
4
Departamento de Física, Universida de Federal do Piauí, Teresina, Brazil
5
Faculdade de EducaçãoCiências e Letras do Sertão Central, Universidade Estadual do Ceará,
Quixadá, Brazil
6
Laboratório de Paleontologia da Universida de Regional do Cariri - LPU, Rua Cel. Antônio Luiz,
Crato, Brazil
1
In the Northeast of Brazil there is an important paleontological region characterized by the occurrence
of several types of Cretaceous fossils with exceptional conservation, the Araripe Basin [1] (meridians 38°
30’ and 40° 50’ W longitude of the Greenwich and parallels 7° 05’ to 7° 50’ S latitude). In this work we
present Raman spectroscopic data on fossil from two different formations of Araripe Basin: Ipubi and
Crato Formations. In the Crato Formation, many fossils of plants were identified: flowers, fruits, roots,
stems, and seeds of different groups. The preservation of such fossils involved diverse mechanisms such
as calcification, limonitization, goetization and sometimes carbonization. In the Ipubi Formation there
are diverse fossil species, in special, fishes and plants. In the present work we show Raman spectra of
plants from the Crato Formation, as well as, from the specie Brachyphyllumcastilhoi from the Ipubi
Formation. Additionally, from the substances found in the fossils, we discuss the possible fossilization
processes and the environment of the Cretaceous Period in the two geological formations.
Raman spectra were collected with a triple-grating spectrometer in the subtractive mode using a
JobinYvon, T64000 equipment. A microscope lens with a focal distance of f = 20.5 mm and a numeric
aperture of NA = 0.35 was used to focus the laser on the sample surface The 514.5 nm line of an argon
ion laser was used in the excitation source with a backscattering geometry.
The Raman spectrum of Brachyphyllumcastilhoi fossil was recorded in the spectral range 250 – 500
cm–1. In the range 330 – 450 cm–1 it is expected to be observed bands associated with S–S vibrations.
These are the Raman signatures of pyrite. It is known that Raman spectroscopy gives information about
libration and stretching vibrations of S – S units.[2] The bands observed at 342 and 377 were assigned,
respectively, as S–S libration and S–S stretching, while a weak band at 428 cm–1 was assigned as a
vibration due coupling of libration and stretching of S – S [2,3]. Beyond the three, it was observed peaks
at 467, 472 cm-1 which were associated to the Si–O–Si bend of quartz (SiO2) and to the Al–O–Si bend
of alumino silicates. Additionally, in other regions of the fossil, Raman spectrum presents vibrations
at 222 cm-1 and 218 cm–1, which were associated to Fe – O bend [2]; however, the bands associated with
pyrite are dominant. From this analysis we were able to understand that the abundance of sulfur and
iron elements in the Cretaceous Period indicates an anoxic environment around the fossilized material
during pyritization. We also concluded that pyritization was an additional fossilization mechanism
in the Araripe Basin, beyond the most known and well stablished process of calcification, which is
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dominant in fossils of another geological formation in the same basin, Romualdo Formation.
We also studied the Raman spectra of two kinds of woods (Gymnosperms, Araucariaceae) from the
Crato Formation: the light wood fossil and dark wood fossil, and their respective matrices. The Raman
spectrum of the light wood matrix presented a peak located at ~ 1087 cm–1, which coincides with the
most intense peak of calcite material [4]. The Raman spectrum of the dark wood matrix presented
peaks at 282 and at 1087 cm–1, which are characteristic of the calcite crystal. In comparison with the
Raman spectrum of the light wood matrix we observed two main differences, i.e., the appearance of
a band at 282 cm-1 and the high intensity of the band at 1087 cm–1. As a consequence, the quality of
the calcite in the dark wood matrix is better than that found in the light wood matrix. The Raman
spectrum of the light wood fossil is very complex. We observed bands at 422, 487 cm–1 which were
associated with symmetric bending of SO4, n2(SO4); modes located in 612 and 659 cm-1, which were
assigned as asymmetric bending of SO4 ions, n4(SO4), and an intense band observed at 992 cm–1 , which
was associated with the symmetric stretching vibration of SO4, n1(SO4). Additionally, a mode observed
at about 1126 cm-1 was associated with the asymmetric stretching of the ion SO4, n3(SO4). In general
terms the spectrum has resemblance with the spectrum of CaSO4.2H2O [4]; such a result was confirmed
with data from X-ray diffraction measurements.
On the other hand, the Raman spectrum of the dark wood fossil is characteristic of materials consisting
of amorphous carbon, which present two main peaks. The first band is observed at 1355 cm–1 and is
known as band of disorder (D band), while the second peak, centered at 1600 cm–1, is assigned as G
(graphitic) band, being related to double bond C = C in materials with such kind of connection. So,
we can conclude the two kinds of wood fossils have different constitutions: while the sample of light
wood fossil is constituted predominantly by CaSO4.2H2O, the dark wood fossil is constituted mainly by
amorphous carbon. From this study we suggest that the origin of the dark wood fossil is a natural fire,
occurred in a dry period, while the origin for the light wood fossil is an environment of high salinity
and high rates of evaporation.
Acknowledgements
This work has been financially supported by CAPES and CNPq.
References [1] P. T. C. Freire, B. T. O. Abagaro, F. E. Sousa Filho, J. H. Silva, A. A. F. Saraiva, D. D. S Brito, B. C. Viana,
Pyritization of Fossils from the Langerstätte Araripe Basin, Northeast Brazil, from the Cretaceous Period.
in Pyrite: Synthesis, Characterization and Uses. 1ed., Nova Science Publishers: Hauppauge, 2013, p. 123.
[2] A. K. Kleppe, A. P. Jephcoat, Mineral. Mag. 2004, 68, 433.
[3] H. Vogt, T. Chattopadhyay, H. J. Stolz, J. Phys. Chem. Solids. 1983, 44, 869.
[4] M. Bouchard, D. C. Smith, in: H. G. M. Edwards, J. M. Chalmers (eds), RamanSpectroscopy in
Archaeology and Art History. The Royal Society of Chemistry: Cambridge, 2005, p. 429.
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Raman spectroscopic analyses of ~75 000 year old stone tools from
Middle Stone Age deposits in Sibudu Cave, KZN, South Africa
Linda C. Prinsloo,1* Lyn Wadley,2 Marlize Lombard3
Physics department, University of Pretoria, Hatfield, South Africa, 27 12 420 2458,
[email protected]
2
Institute for Human Evolution and the School of Geography, Archaeology and Environmental
Studies,
University of the Witwatersrand
3
Department of Anthropology and Development Studies, University of Johannesburg, Auckland Park
Campus, Johannesburg 2006, South Africa
1
Sibudu is an extremely important Middle Stone Age rock shelter located on the Tongati River near the
KwaZulu-Natal coast of South Africa. It has a large collection of Middle Stone Age deposits that are
well preserved and have been accurately dated using OSL (optically stimulated luminescence), giving
an occupation span of 77 000 to 38 000 years ago. Direct evidence was found for the use of ochre in
the hafting technology of tools from the shelter and replication studies of adhesives that may have been
used for hafting the tools show that ochre is indeed useful as loading agent for adhesives.[1,2]
Optical microscopic investigations of the stone tools showed that the distribution patterns of ochre and
resinous material coincide with the blunted side of the tools, usually associated with hafting, suggesting
that the compound mixture was used to glue the tools to their hafts (see Figure 1).
Figure 1. An example of a stone tool where the darker coloured hafting side can clearly be
distinguished from the working edge (left). Raman spectra recorded on stone tools from
Middle Stone Age deposits in Sibudu Cave, KZN, South Africa (right).
Raman spectra were recorded on both sides of various stone tools from the site with an Alpha WiTec
Raman instrument using a 514.6 nm laser as excitation source. Spectra were recorded on both the
hafted and working (sharp) sides of each stone tool. An example of the results is presented in Figure 1
where the strongest peak (463 cm-1) in spectrum (a) belongs to a-quartz (found on both the working and
hafting sides). Other phases identified through their Raman spectra are hematite (spectrum c, 216, 275
cm-1) recorded on the hafting side, bone (spectrum f, 962 cm-1) on the working side and the interface
between sides, calcium carbonate (spectrum g, 1087 cm-1) is randomly distributed and carbonaceous
material (spectra d and e, 1350, 1580 cm-1) primarily on the hafting sides. In some spectra more than
one phase can be identified.
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The presence of a-quartz originates from the stone matrix of the tool. The hematite spectra are in
line with the microscopic evidence for the use of ochre in the hafting technology and they resemble
spectra recorded from ochre from the Wonderwerk Cave in South Africa.[3] The detection of bone
on the working edge of the tool suggests that it was used on animals and the presence of residues
at the interface between hafting and working edge is due to the accumulation of material where the
original hafting configuration terminated on the stone surface. The calcium carbonate is probably from
ash, which is abundant in combustion features at the site. The spectra of carbonaceous material range
from highly graphitic to amorphous (spectra d and e). It has been shown that fruit and nuts buried
underneath hearths in anoxic conditions become carbonized to different extents depending on the
distance from the fire, and the carbon is therefore most likely due to the original plant gum that has
undergone the same post-burial changes as the fruit and nuts.[4]
This study validated the work that has so far been done using microscopy and highlights the usefulness
of Raman spectroscopy in the study of Middle Age Stone tools and opens up a whole new avenue of
experimentation.
Acknowledgements
The authors wish to thank the NRF, and the Universities of Pretoria, the Witwatersrand and
Johannesburg for their financial support. Results and inferences are, however, those of the authors and
not the funding or supporting institutions.
References
[1] L. Wadley, J. Hum Evol. 2005, 49(5), 587–601.
[2] M. Lombard, J. Hum Evol. 2007, 53(4), 406–419.
[3] L. C. Prinsloo, A. Tournié, P. Colomban, C. Paris, S. T. Bassett, J. Archaeol Sci. 2003, 40(7), 2981–
2990
[4] C. Sievers, L. Wadley, J. Archaeol Sci. 2008, 35, 2909–2917.
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Raman spectroscopy in archaeometry: multi-method approaches
and in situ investigations: advantages and drawbacks
Peter Vandenabeele,1* Luc Moens2
Research group in Archaeometry, Department of Archaeology, Ghent University, Ghent, Belgium,
[email protected]
2
Raman Spectroscopy Research Group, Department of Analytical Chemistry, Ghent University, Ghent,
Belgium
1
In archaeometry, it is the aim to maximise the amount of information that is obtained from an object
while minimising the risk on damage to the art object. This criterion can be met by using several
complementary analytical techniques, especially when these techniques are compatible to perform
in situ investigations. The current research paper focusses on these two important aspects of current
archaeometrical projects: on the one hand the use of multi-analytical approches (where Raman
spectroscopy is combined with other non-destructive analytical techniques) and on the other hand
the state-of-the art of mobile analytical approaches.
Raman spectroscopy has grown to be one of the preferred techniques when investigating art objects.
Indeed, the technique is well-appreciated for, amongst others, its non-destructive character, the
possibility to obtain molecular information at a micrometer-level and its speed of analysis. Moreover,
this is a very versatile analytical approach, that allows the archaeometrist to obtain analytical
information from a very broad range of materials (e. g. pigments, glass, ceramics, minerals, glazes,
corrosion products, gemstones, biomaterials, etc.) of different periods. However, where we highly
esteem the possibilities of the approach, sometimes it can be useful to complement the approach with
other analytical techniques, so that more complete information is obtained. When using multiple
analytical techniques, this has some implications towards the analytical procedures concerning
planning, documenting and the workflow of the approach.
One of the main advantages of Raman spectrosocpy, is that it can be used to investigate an artwork
directly – thus reducing the need for sampling. Today, several Raman instruments are available for in
situ investigations. However, all approaches have their advantages and drawbacks. In this presentation,
we will focus on the specific needs in archaeometry, to have a versatile, yet mobile Raman spectroscopic
approach. This will be illustrated with a broad range of applications from daily lab practice: the analysis
of pigments, manuscripts, paintings and ceramics.
Acknowledgements
The authors wish to acknowledge the MEMORI project for their financial support and for the interesting
discussions with the colleagues. The MEMORI, ‘Measurement, Effect Assessment and Mitigation
of Pollutant Impact on Movable Cultural Assets. Innovative Research for Market Transfer‘, project
is supported through the 7 th Framework Programme of the European Commission (http://www.
memori‑project.eu/memori.html).
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Spectroscopic Analysis of Chinese Porcelain Excavated in
Clairefontaine (Belgium): Pigment Identification and Dating
Jolien Van Pevenage,1* Debbie Lauwers,1 Davy Herremans,2 Eddy Verhaeven,3
Bart Vekemans,4 Wim De Clercq,2 Laszlo Vincze,4 Luc Moens,1
Peter Vandenabeele2
Raman Spectroscopy Research Group, Department of Analytical Chemistry, Ghent University, Ghent,
Belgium, +32 9 2644719, [email protected]
2
Department of Archaeology, Ghent University, Ghent, Belgium
3
Department of Conservation and Restauration, Artesis Hogeschool Antwerpen, Antwerp, Belgium
4
Department of Analytical Chemistry, Ghent University, Ghent, Belgium
1
The porcelain objects, investigated in this project, were found in a latrine of the Cistercian abbey of
Clairefontaine (Belgium). From archaeological point of view, based on the shape and the style, the
porcelain objects are thought to be Chinese, dating from the first half of the 18th century. However
most of these chronologies have kept up for years and are rarely supported by absolute dating or
determination of the origin. By doing spectroscopic research on these samples, more certainty about
the production date and origin of these samples can be retrieved.
According to the macroscopical analysis of the decoration patterns, the Clairefontaine porcelain could
be divided in two main groups. Group A consists of porcelain characterized by an abundantly blueand-white decoration. A variety of designs appear such as crabs, flowers and Chinese landscapes. A
limited part of the vessels was painted brown on the surface. Both designs and colour patterns suggests
a production under emperor Kangxi (1661-1722) [1]. The second group comprises porcelain with more
colourful decoration. Both decoration and colour range suggests a production under emperor Qianlong
(1735-1795). A variety of designs appear including Chinese landscapes, rural sceneries with birds,
flowers and rodents, and more abstract floral decoration. Typical for Qianlong porcelain is the wide
range of pigments used for the application of these desings [1–2]. The colour range on the Clairefontaine
vessels consists of gold, red and green. All the objects of group B have a brown decorated exterior.
In this project, both Raman spectroscopy and X-Ray Fluorescence (XRF) spectroscopy are used for
the characterization and identification of the samples. By using these two complementary techniques
we gather molecular (Raman) and elemental (XRF) information about the different porcelain objects.
All groups and subgroups were sampled. A set of 36 samples covering the variety of pigments was
separated for further analysis. Before Raman and XRF analysis, samples are cut, embedded and
polished, in order to be able to measure on the transversal side of the samples.
The glaze layers of the porcelain objects were analysed. The following results are obtained: the samples
of group A were probably produced under emperor Kangxi (1661–1722), based on the presence of cobalt
blue (CoAl2O4). The identification of hematite (α-Fe2O3) and malachite (Cu2CO3(OH)2) ascertains without
doubt that the objects of groups B1, B2 and B3 were produced during the Qing period (1644–1922). In
the glaze layers of the samples of group B1, also an opaque lead tin yellow type II (PbSn1-xSixO3, where
x ~ ¼), and an opaque lead acetate were identified, which indicates that these samples date from the
emperor Qianlong (1735–1795), more precisely. These former two pigments belong to the colour pallet
of famille rose porcelain, which was very famous during this period. At last, the golden colour was
identified as a mixture of gold and lead.
It can be concluded that Raman and XRF spectroscopy form a perfect match for the analysis of Chinese
porcelain as it are complementary and non-invasive techniques, which allow identification of pigments,
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used to colour the glaze layers, with the result that retrieving the production date of porcelain objects
becomes possible.
Acknowledgements
Special acknowledgments go to Prof. dr. J. De Meulemeester (†), who directed archaeological fieldwork
at Clairefontaine, and to the Walloon Governement, ©SPW-DPat, who financed this project. Postexcavation research is carried out within the framework of the PhD-project (FNR Luxembourg–
BFR06-80): “The material culture of Clairefontaine abbey”.
References
[1] J. Wu, P. L. Leung, M. J.Stokes, M. Li, X-Ray Spectrometry. 2000, 29, 239–244.
[2] J. Miao, B. Yang, D. Mu, Archaeometry. 2010, 52, 146–155.
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Characterization of ancient ceramic using micro-Raman
spectroscopy: the cases of Motya (Italy) and Khirbetal-Batrawy
(Jordan)
Laura Medeghini,1* Pier Paolo Lottici,2 Caterina De Vito,3
Silvano Mignardi,3 Danilo Bersani,2 Mariangela Turetta,2 Jennifer Costantini,2
Elena Bacchini,2 Maura Sala,4 Lorenzo Nigro4
PhD in Applied Sciences for the Protection of the Environment and of Cultural Heritage,
Department of Earth Sciences, Sapienza University, Rome, Italy,
+39 0649914155 [email protected]
2
Department of Physics and Earth Sciences, University of Parma, Parma, Italy.
3
Department of Earth Sciences, Sapienza University, Rome, Italy.
4
Department of Sciences of Antiquities, Sapienza University, Rome, Italy
1
In the last years, the number of scientific contributions in which Raman spectroscopy is the key
technique to analyze archaeological objects is continuously increasing. In particular, the application of
this non-destructive technique in the characterization of ancient ceramic has received a major boost.
The spectroscopic information obtained by Raman analysis allows for the mineralogical characterization
of pottery, answering to the main questions of archaeologists about the nature and provenance of raw
materials for ceramic production, as well as exploring the technological aspects of the firing conditions
and post-burial processes.[1-8]
We report in this study two different types of ceramics in terms of technological fingerprints and
preparation of the raw materials with the aim to show how micro-Raman spectroscopy can answer the
above questions.
Micro-Raman spectroscopy has been applied on ancient ceramics from two archaeological sites of the
Mediterranean area and Near East. The first case is Punic “Black-Gloss Ware” from the PhoenicianPunic site of Motya (Sicily, Italy), dating back from the end of 6th to the early 4th century B.C. These
ceramics are the result of a high technological background due to imitation of the most famous Attic
production, diffused in all Mediterranean world.
As a second case study, pottery samples with lower technological background have been selected from
the archaeological site of Khirbet al-Batrawy (Jordan), dating back in the III millennium B.C.
The use of micro-Raman spectroscopy allowed us to characterize the mineralogical composition of
the vessels fragments in order to define the pottery composition and the firing conditions, the nature
of the black gloss of Motyan ceramics and of the superficial decorations of Jordan ceramic. Moreover,
Raman results combined with those obtained by optical microscopy, X-ray diffraction and SEM-EDAX
analysis helped in the reconstruction of the raw material provenance.
In the case of Motya samples, the internal body is composed by quartz, feldspars, pyroxenes, micas,
gehlenite, magnetite, and haematite. In addition to previous minerals hercynite also occurs in the
black gloss. Chemical data showed that the main body and the black gloss contained the same major
elements: Si, Al, Fe, Ca, K, Mg, Ti, and Na. However, a Fe-enrichment in the black gloss has been
observed. The ceramic samples were exposed to similar firing temperatures and fO2 as suggested by
mineral assemblage: estimated T is the range 1000-1100 °C at oxidizing-reducing-oxidizing conditions.
The potential sources of raw materials used for ceramic production are difficult to infer as the starting
material was selected and purified; however, the presence of a kiln in Motya proves a local production.
[9]
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In the Khirbet al-Batrawy pottery, calcite and quartz are the main components. Hematite, magnetite
and carbon are frequently found in all samples. K-feldspar, plagioclase, apatite, gypsum, titanium
dioxide (anatase and rutile), pyroxenes, bassanite, barite, zircon, and olivine have been detected in
minor amounts and only in few samples. Detailed micro-Raman analysis has been carried out on
the superficial decorations of fragments. Raman spectra revealed the occurrence of hematite in red
decorations, whereas amorphous carbon has been found in the black ones. The co-presence of calcite,
diopside, anatase, and rutile, mineral phases having different thermal fields of stability, allows to
hypothesize a firing temperature range of Khirbet al-Batrawy ceramic between 850 and 900 °C. The
diffuse occurrence of hematite probably indicates an oxidizing atmosphere during firing, whereas the
presence of magnetite could indicate an incomplete transformation from magnetite to hematite.[10]
The exhaustive information about mineralogical composition in potteries obtained allows to define the
technological process of production, underlining the key role of micro Raman spectroscopy in the study
of archaeological ceramic.
Figure 1.Views of the two archaeological sites: Motya a.) and Khirbetal-Batrawy b.).
References [1] G. Barone, S. Ioppolo, D. Majolino, P. Migliardo, G. Tigano, J. Cult. Herit. 2002, 3, 145.
[2] C. M. Belfiore, M. di Bella, M. Triscari, M. Viccaro, Mater. charact. 2010, 62, 440.
[3] G. Cultrone, C. Rodriguez-Navarro, E. Sebastian, O. Cazalla, M. J. De La Torre, Eur. J. Mineral. 2001, 13,
621.
[4] A. Iordanidis, J. Garcia-Guinea, G. Karamitrou-Mentessidi, Mater. Charact. 2009, 60, 292.
[5] L. Maritan, Eur. J. Mineral. 2004, 16, 297.
[6] C. Rathossi, P. Tsolis-Katagas, C. Katagas, ApplClaySci, 2004, 24, 313.
[7] C. Tschegg, J. Archeol. Sci. 2009, 36, 2155.
[8] G. Velraj, K. Janaki, A. M. Musthafa, R. Palanivel, Appl. ClaySci. 2009, 43, 303.
[9] G. Falsone, Struttura e origineorientaledeiforni del vasaio di Mozia, Fondazione G. Whitaker: Palermo,
1981, p. 89.
[10]C. Lofrumento, A. Zoppi, E. M. Castellucci, J. RamanSpectrosc. 2004, 35, 650.
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Hispano-Moresque architectural tiles from the Monastery of Santa
Clara-a-Velha, in Coimbra, Portugal: a µ-Raman study
Susana Coentro,1,2 Rui M. C. Silva,2 Vânia S. F. Muralha1
VICARTE – Research Unit “Glass and Ceramics for the Arts”, Faculdade de Ciências e Tecnologia da
Universidade Nova de Lisboa, Caparica, Portugal
2
Instituto Tecnológico e Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa,
Sacavém,Portugal
1
In the last decades of the 20th century, several archaeological campaigns in the Monastery of Santa
Clara-a-Velha, in Coimbra, brought to light an impressive collection of Hispano-Moresque glazed
tiles. Among this collection, dated from the 15th and 16th centuries, we find complex techniques such
as cuerda-seca, arista and relief, but also simpler techniques as flat monochromatic tiles. There
were also excavated unglazed arista pieces and a large number of trivets, which casted doubts on the
subject of provenance, usually attributed to Seville, in Spain.
This study is focused on the chemical and morphological characterisation of the tile collection from
the Monastery of Santa Clara-a-Velha, with the intent of understanding its production technology
and gather information to later compare with other Hispano-Moresque tile collections in Portugal
and Spain. In this context, both the ceramic bodies and glazes of the tiles were analysed by μ-Raman
spectroscopy.
A typical Raman spectrum of a glass or glaze material shows two main broad bands, corresponding
to the Si-O bending vibration (about 500 cm-1) and the Si-O stretching vibration (about 1000 cm1
). The shape, intensity and mathematical fitting of these bands are characteristic of a certain glass
composition, and can infer on processing temperatures of manufacture, substitution patterns and
discriminating between different groups. In this study, the band at 1000 cm-1 is always stronger, as it is
characteristic for lead glazes. Differences in intensity and shape of the bands are detected for differentcoloured glazes and it will be discussed alongside the glazes quantitative data.
Another important element that m-Raman can provide is the characterization of the glaze-ceramic
interface (where chemical reactions occur during firing and new crystalline phases are formed), an
important aspect in glazed ceramics to understand the production technology. These crystals depend
on the chemical composition of the glaze and the ceramic paste, and also on the firing conditions. Glazes
are very homogeneous and only cassiterite (SnO2), was identified very well distributed through all the
glaze depth. Other crystalline phases were only identified in interface and seem to be the outcome
of the reaction between the lead glaze and the calcium-rich ceramic body. Some phases identified
include wollastonite (CaSiO3), andradite (Ca3Fe2Si3O12) malayite (CaSnOSiO4) crystals, and bustamite
(CaMnSi2O6). The results will be discussed according to the glaze colour composition.
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The blue colour of glass and glazes in Swabian contexts (South of
Italy): an open question
Maria Cristina Caggiani,1,3 Pasquale Acquafredda,2 Philippe Colomban,3
Annarosa Mangone1*
Chemistry Department, Bari University “Aldo Moro”, Bari, Italy,
+39805442117, [email protected], +39805442022, [email protected]
2
Earth Science and Geo-Environmental Department, Bari University “Aldo Moro”, Bari, Italy,
3
Ladir umr 7075, CNRS, Université Pierre et Marie Curie, c49, Paris France,
+33-144272785, [email protected]
1
The most known and studied medieval enamelling productions occurred in the Islamic culture with the
gilded and enamelled works produced between the 13th and 14th centuries. In literature, some earlier
groups of objects attesting the existence of an anterior manufacturing, also of different provenances,
are documented, such as the Roman Lübsow beaker (first half of 2nd cent. AD)[1] and the Begram treasure
(1st-2nd cent. AD). The recent discovery of enamelled glass objects (Figure 1a) in Frederick II Melfi castle
(South of Italy), with a dating prior to the end of the 13th century, brings into question the exchanges of
knowledge, technological procedures, raw materials and artefacts.
In this work, importance is given to the blue colour because in our specific case it can provide clues
about technological choices and economic circumstances. Recently, archaeometric studies are strongly
contributing to demonstrate that a material considered for long time extremely precious, of difficult
availability and expensive like lapis lazuli was actually used more often and in more differentiated
geographical contexts than thought. One case is that of pottery glazes and glass fragments where lapis
lazuli was found coming from different contexts connected to Frederick II influence: the abandoned
Medieval village of Castel Fiorentino, the fortress in Lucera, the only surviving mosaic tile of the
original mosaic decoration of Castel del Monte,[2] and the medieval sea port of Siponto.[3]
Also the Raman analyses conducted on the blue enamels of Melfi samples showed the presence of the
radical anions chromophores S2- S3-, typical of lazurite mineral, principal constituent of lapis lazuli.
In this case, though, due to the presence, in the same area of the archaeological findings, of two rocks
that contain haüyne, a mineral belonging to sodalite group like lazurite: Phonolite of Toppo San Paolo
(Figure 1b’) and Haüynophire of Melfi, the latter located exactly at the foot of the town, a question arose
on the real nature of the enamels raw materials, in the lack of local artisans manuscripts of receipts
and procedures.
In order to understand if the chromophore-bearing mineral in the artefacts could be other than lazurite,
the two volcanic rocks and some archaeological samples with blue enamels were subjected to a study
through Optical Microscopy (OM), Raman micro-spectroscopy and micro X-ray Diffraction (µ-XRD).
In the rocks, particular attention was given to the haüyne crystals that can be blue or become blue after
heating (Figure 1b’’).[4]
Flat-surfaces chunks of the rocks phonolite and haüynophire were heated up to different temperatures
(400, 700, 900°C) and after observed through optical microscopy and analysed by micro-Raman
spectroscopy at different wavelengths, also by means of areal mappings after each step. Raman analyses
were also carried out on single crystals of lazurite and haüyne during heating and cooling in a special
temperature controlled chamber up to 900°C in order to follow the crystal evolution during the entire
process.
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The results obtained allowed to understand that a transformation occurs in haüyne mineral starting
from about 700°C, after which the Raman spectrum shows an increase in intensity and diffusion in the
crystal of the S2- S3- signature, the same as lazurite chromophores whose absorbance spectrum was in
this work experimentally reconstructed.
Figure 1. a.) one of the samples of gilded and enamelled glass from Melfi; b) optical microscope (OM) micro-photographs of
thin sections of fragments of phonolite rock: b.) in the not-heated sample, haüyne crystals are from colourless to black, b.) in the
heated one (900°C for 11 days) they appear blue.
The preliminary results obtained on real samples of blue enamels would lead to think to the use of lapis
lazuli, but this will be better seen with further studies and experimental archaeology productions of
glass including haüyne-bearing rocks.
References
[1] S. Greiff, J. Schuster, J. of Cultural Heritage. 2008, 9 (Supplement 1), 27.
[2] I. M. Catalano, A. Genga, C. Laganara, R. Laviano, A. Mangone, D. Marano, A. Traini, J. of Archaeological
Science. 2007, 34, 503.
[3] A. Traini, L. C. Giannossa, R. Laviano, A. Mangone, Le indagini archeometriche dei reperti ceramici, in
C. Laganara (Ed.): Siponto. Archeologia di una città abbandonata nel Medioevo. Claudio Grenzi: Foggia,
2011, p. 133.
[4] P. Ballirano, Physics and Chemistry of Minerals. 2012, 39(9), 733.
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Spectroscopic characterisation of crusts interstratified with
prehistoric paintings preserved in open-air rock art shelters
Antonio Hernanz,1* Juan F. Ruiz-López,1 Juan Manuel Madariaga,2 Egor Gavrilenko,3
Maite Maguregui,2 Silvia Fdez-Ortiz de Vallejuelo,2 Irantzu Martínez,2 Ramiro AllozaIzquierdo,4 Vicente Baldellou-Martínez,5 Ramón Viñas-Vallverdú,6 Albert Rubio i
Mora,7 África Pitarch,2 Anastasia Giakoumaki2
Departamento de Ciencias y Técnicas Fisicoquímicas, Facultad de Ciencias, Universidad Nacional de
Educación a Distancia (UNED), Madrid, Spain, +34 91 398 7377, [email protected]
2
Department of Analytical Chemistry, Faculty of Science and Technology, University of Basque
Country, Bilbao, Spain, [email protected]
3
Instituto Gemológico Español, Madrid, Spain, [email protected].
4
Laboratorio de Análisis e Investigación de Bienes Culturales, Gobierno de Aragón, Zaragoza, Spain,
[email protected]
5
Museo de Huesca, Huesca, Spain, [email protected]
6
Ramón Viñas-Vallverdú, Dr., Instituto Català de Paleoecología Humana y Evolució Social (IPHES),
Tarragona, Spain, [email protected]
7
Centro Asociado de Cervera, Cervera, Lleida, Spain, [email protected]
1
One of the main difficulties applying on-site and laboratory m-Raman spectroscopy to study prehistoric
paintings from open-air rock shelters is the presence of layers of fluorescent materials interstratified
with the pigment.[1] A considerable number of on-site m-Raman analytical campaigns in significant
open-air rock art sites from the Iberian Peninsula have undergone this problem. The objective of this
work is to characterise the composition and microestratigraphic distribution of these layers, to infer
its origin and to present methods to deal with this difficulty. The painting panels of the rock shelters
Cova dels Rossegadors (Pobla de Benifassà, Castellón), Cueva de la Vieja and Cueva del Queso (Alpera,
Albacete), Los Chaparros (Albalate del Arzobispo, Teruel) and Riquelme (Jumilla, Murcia) in the Iberian
Peninsula have been studied. This work collects the results of several archaeological seasons in these
sites developed by diverse researchers; hence the large number of co-authors. On-site and laboratory
m-Raman spectroscopy have been applied. SEM/EDX and polarized optical microscopy have been
used as auxiliary techniques.
Previous on-site EDXRF screening analyses of the walls were very useful to detect elemental signals
from pigments that are covered by crusts and remain hidden to the human eye, an advantage of the
EDXRF penetration depth. The presence of a supposed pictograph in Cova dels Rossegadors has
been confirmed this way. Different layers of accretions have been discovered in this site studying
thin cross sections, Figure 1. A thick crust made difficult the on-site m‑Raman study of the Cueva de
la Vieja pigments. The repeated spraying of water to exhibit clearly the pictographs, an unfortunate
frequent practice, has caused this crust. A deplorable example of anthropic deterioration. The walls
of Los Chaparros and Riquelme rock shelters appear covered by an orange crust that produces strong
fluorescence radiation even exciting at 785 nm. Wind-blown dust and surface water runoff could have
contributed to form some of these crusts. Clay minerals, clayey loams, marls, calcite and dolomite are
the most frequent components found in the crusts. In spite of these difficulties, a careful selection
of the operating conditions of the spectrometers made possible in some cases to record acceptable
Raman spectra. On the other side, the finding of interstratified layers of calcium oxalate (whewellite
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and weddellite) with the pigment is very helpful to achieve the AMS 14C dating of the paintings, a
fundamental objective for the archaeologists.[2-4] These methodology can be applied to other shelters,
where men have left paintings preserved during thousands of years.
Figure 1. Microphotograph with polarised
light of a thin section of the crusts
interstratified with prehistoric paintings in the
Cova dels Rossegadors rock shelter, Pobla de
Benifassà, Castellón, Spain.
Acknowledgements
We gratefully acknowledge Dr. S. Martin (Dept. Física Matemática y Fluidos, UNED) for their help in
recording SEM/EDX data. This work has been financially supported by project I+D+i CTQ2009-12489
from Ministerio de Ciencia e Innovación and funds from Dept. Analytical Chemistry (EHU, Bilbao,
Spain).
References
[1] A. Hernanz, J. F. Ruiz-López, J. M. Gavira-Vallejo, S. Martin, E. Gavrilenko, J. of Raman Spectrosc. 2010,
41, 1104–1109.
[2] A. Hernanz, J. M. Gavira-Vallejo, J. F. Ruiz-López, J. of Optoelectronics and Advanced Materials. 2007, 9,
512–521.
[3] J. F. Ruiz, M. M. Mas, A. Hernanz, M. W. Rowe, K. L. Steelman, J. M. Gavira, International Newsletter on
Rock Art. 2006, 46, 1–5.
[4] J. F. Ruiz-López, A. Hernanz, R. A. Armitage, M. W. Rowe, R. Viñas, J. M. Gavira-Vallejo, A. Rubio, J. of
Archaeologial Science. 2012, 39, 2655–2667.
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Micro-Raman on Roman glass mosaic tesserae
Claudia Invernizzi,1,2* Elena Basso,1,3 Marco Malagodi,1,4
Mauro Francesco La Russa,5 Danilo Bersani,2 Pier Paolo Lottici2
Laboratorio Arvedi-CISRiC, Università di Pavia, Italy, [email protected]
Dipartimento di Fisica e Scienze della Terra, Università di Parma, Italy, [email protected],
[email protected]
3
Dipartimento di Scienze della Terra e dell’Ambiente, Università di Pavia, Italy, [email protected]
4
Dipartimento di Chimica, Università di Pavia, Italy, [email protected]
5
Dipartimento di Scienze della Terra, Università della Calabria, Arcavacata di Rende, Cosenza, Italy,
[email protected]
1
2
The results of a Micro-Raman spectroscopy investigation performed on twenty-one Roman glass
mosaic tesserae (II century A.D.), from the “Villa dei Quintili” excavation in Rome, are reported. The
set of tesserae was retrieved in the thermal baths and covers the majority of the colour palette of that
time. The aim was to identify the raw materials, the colouring agents and the opacifiers as well as the
production technology used during the Roman Imperial Age.
FESEM-EDS and LA-ICP-MS were also employed for a detailed spectroscopic characterization of both
the glass matrix and the crystalline inclusions.
The tesserae are made by soda-lime glass produced with natron as flux. For some red samples higher
levels of MgO e K 2O suggest the use of plant-ashes as a source of alkali.
Sn-Pb antimonates (yellow), Ca-antimonates (white), a mixture of Cu2+ ions and Sn-Pb antimonates
(green), a mixture of Ca-antimonates and Cu2+ or Co2+ ions (blue and blue-green) are the colouring and
opacifying agents used. Cu0 metal nanoparticles and Cu2O nanocrystals are found in the red and orange
lead-containing tesserae. The results confirm the high technological level of Imperial Age glassmakers
and emphasize the importance of complementary micro-analytical (SEM-EDS and LA-ICP-MS) and
spectroscopic (µ-Raman) techniques.
Figure 1. Raman spectra of calcium antimonates:
a.) CaSb2O6, b.) Ca2Sb2O7
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Raman and IR Spectroscopic Study of Vitreous Artefacts from the
Mycenaean to Roman Period: Glassy Matrix & Crystalline Pigments
Doris Möncke,1* Eleni Palamara,2 Dimitri Palles,3 Efstratios I. Kamitsos,3
Nikos Zacharias,2 Lothar Wondraczek1
Otto-Schott-Institut, Friedrich-Schiller-Universität, Jena, Germany,
+49-3641-948505, [email protected], [email protected].
2
Laboratory of Archaeometry, Department of History, Archaeology and Cultural Resources
Management, University of Peloponnese, Kalamata, Greece, [email protected], [email protected]
3
Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Athens,
Greece, [email protected], [email protected]
1
Coloured glasses and glass ceramics such as glazes, enamels or mosaic tesserae were studied in
regard to the glass structure and for eventual present crystalline particles. The samples come from
the Peloponnese and belong to the Mycenaean, Classic Hellenic and Roman Period. Attic black glazed
fragments from the Classical period and glazed pottery from Corinth of the ‘Byzantine period were also
included in this study.
Quantitative analysis by SEM/EDX is available for most samples while some had also been studied
by X-ray diffraction for the identification of crystalline minerals, or by optical spectroscopy for the
absorption bands of dissolved transition metal ions used as colourants.
Reflectance infrared spectroscopy (IR) and the FT-IR microscope were used for structural studies of
the glass samples and the vitreous substrate of glazes, enamels or tesserae. Micro-Raman analysis
complimented these studies and helped additionally via Raman fingerprint spectral identification in
the characterization of various opacifiers and colouring pigments.
Thermal properties (transition, melting and crystallization temperature) of the glass substrate and
the identified pigments can be used to deduce the outer limits of possible process windows during
preparation of these vitreous artefacts. Such information will help in distinguishing pigments which
were added at some point to the melt but did not fully dissolve, from crystalline particles which only
precipitated upon cooling of the melt, or from particles which might even need an additional annealing
step in which the finished glass sample was tempered in a second production step for a certain time. The
identified pigments will also be compared with naturally occurring pigments in order to distinguish
these from artificially prepared crystalline particles.
The variation of different pigments and different combinations of opacifiers and pigments in different
regions and over time will be studied in various vitreous materials.
Figure 1. Classic Hellenic vessel fragment of a cobalt
blue coloured glass matrix and decorative lining.
Raman spectroscopy identified the yellow pigment
Naples Yellow (Pb2Sb2O7) and in both, the white and
yellow lines also the white opacifier CaSb2O6.
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Acknowledgements
DM wants to thank the Fritz Thyssen Foundation for financial support.
References [1] D D. Möncke, D. Palles, N. Zacharias, M. Kaparou, E. I. Kamitsos, L. Wondraczek, Phys. Chem. Glasses: Eur.
J. Glass Sci. Technol. 2013, B54, 52–59.
[2] M. Papageorgiou, N. Zacharias, K. G. Beltsios, Analytical and Typological Investigation of Late Roman
mosaic tesserae from Ancient Messene, Greece, Proceedings of the ΑΙHV 18, D. Ignatiadou, A. Antonaras
(eds.), Thessaloniki, 2012, 241–248.
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The detection of Copper Resinate pigment in works of art:
contribution from Raman spectroscopy
Irene Aliatis,1* Claudia Conti,2 Geneviève Massonnet,3 Cyril Muehlethaler,3
Tommaso Poli,4 Matteo Positano,5 Elena Possenti,2 Jana Striova6
University of Parma, Dep. DIFEST, Parma , Italy, +390521905206, [email protected]
ICVBC-CNR, Milan, Italy
3
University of Lausanne, School of Forensic Science, Institut de Police Scientifique, Lausanne
Dorigny, Switzerland
4
University of Turin, Dep. Chemistry I.F.M., Turin, Italy
5
Emmebi diagnostica artistica s.r.l., Rome, Italy
6
CNR-INO and LENS, University of Florence, Sesto Fiorentino, Italy
1
2
Copper resinate is a green pigment widely used in the 16th century by Italian painters, as many surveys
on Caravaggio[1] and on Flemish paintings proved.[2] This pigment consists of a transparent green
glaze and its colour is obtained by copper salts of resin acids. The composition of this compound is
controversial and a great variety of recipes exists. Verdigris is always the principal ingredient giving
the glaze its green colour and old recipes suggest the preparation of copper resinate by mixing verdigris
with terpenic resins, as Venice turpentine (conifer resins).[2]
Given the complexity of the nature of copper resinate, its identification is matter of debate. In several
cases, the detection of this pigment has been based only on the observation of its morphology;[1] the
identification of its characteristic FTIR pattern[3] is generally quite uncertain due to the copresence of
the binder and other pigments. To date, the best analytical technique for the detection of copper resinate
is gas chromatography coupled with mass spectrometry (GC-MS). This method allows identifying the
terpenic compounds and their characteristic oxidation products,[4] but it is a sample destroying and
relatively time consuming technique. At the present time, there are a few Raman studies of copper
resinate published in literature; generally fluorescence obscures the Raman scattering[5] or weak bands
make its characterization difficult.[6] Raman analyses carried out by the authors during the last years
on several paintings, included “Madonna dei Pellegrini” by Caravaggio (Figure 1), highlighted the need
of an extensive study of the Raman vibrational features of copper resinates. Therefore, the aim of this
work is to study copper resinates available on the market nowadays and thus to verify the possiblity
of Raman identification of this pigment in paintings. Commercial copper resinate pigments have been
also characterized by elemental and microscopical analyses (portable XRF and SEM-EDS) as well as
by FTIR spectroscopy.
488, 514, 532, 633, 785 and 830 nm laser lines of different Raman spectrometers have been used to
analyze raw samples and painted layers prepared spreading copper resinate with linseed oil.
Collected spectra have been compared to the ones of verdigris in order to identify the Raman lines
specific of the two green pigments. The comparison of the Raman spectra recorded by different sources
highlighted the possibility to distinguish copper resinate from the other green pigments; Raman spectra
will be presented, discussed and compared with FTIR spectra.
References
[1] P. D. Weil, Rev. Bras. Arqueometria, Restauraçao e Conservaçao. 2007, 1, 106.
[2] H. Kühn, Artists’ Pigments. A Handbook of Their History and Characteristics, vol. 2, Oxford University
Press: Oxford, 1997, p. 131.
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[3] H. Kühn, Stud. Conserv. 1970, 15, 12.
[4] M. P. Colombini, G. Lanterna, A. Mairani, M. Matteini, F. Modugno, M. Rizzi, Ann. Chim-Rome. 2001, 91,
749.
[5] S. Daniilia, D. Bikiaris, L. Burgio, P. Gavala, R. J. H. Clark, Y. Chryssoulakis, J. Raman Spectrosc. 2002,
33, 807.
[6] M. L. Franquelo, A. Duran, L. K. Herrera, M. C. Jimenez de Haro, J.L. Perez-Rodriguez, J. Mol Struct. 2009,
404, 924–926.
Figure 1. a.) Detail of “Madonna dei Pellegrini” by Caravaggio, 16041606, Basilica di Sant’Agostino, Rome. The black square indicates the
sampling point. b.) Cross section of the sample; the white segment
indicates the investigated layer, likely composed of copper resinate.
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Micro-Raman and internal micro-stratigraphic analysis of the
painting materials in the rock-hewn church of the Forty Martyrs in
Şahinefendi, Cappadocia (Turkey)
Claudia Pelosi,1* Giorgia Agresti,1 Maria Andaloro,1 Pietro Baraldi,2
Paola Pogliani,1 Ulderico Santamaria1
Department of Cultural Heritage Sciences, University of Tuscia, Viterbo, Italy,
2
Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia,
Modena, Italy, +390592055087, [email protected]
1
The aim of this work is to investigate the pigments, the mortars and the degradation products in the
wall paintings of the Forty Martyrs church, a medieval rock-hewn settlement in Cappadocia, the
central region of Turkey (UNESCO Heritage). This work is part of a wider research project called “Rock
paintings in Cappadocia. For a project of knowledge, conservation and enhancement of the church of
the Forty Martyrs at Şahinefendi and its territory”. The study of the extraordinary pictorial complex
of Cappadocia is a prerequisite knowledge necessary to carry out its conservation, restoration and
valorization. It is worth stressing that the rock hewn wall paintings are the result and the peculiar
expression of Cappadocia’s environmental scenic context where the permanent union between a
stunning landscape and the painted churches constitutes the very identity of this area.
The Forty Martyrs church is characterized by wall paintings applied on pink-white mortars sometimes
containing vegetable fibers. The plaster was generally spread by means of large horizontal bands relating
to the scaffolding lifts. A conservation work was performed in order to unveil the wall paintings covered
by a thick sooty layer due to the fires lit in the past. The cleaning intervention revealed a wide figurative
cycle which develops throughout the two naves of the church (see figure below).[1]
The various aspects of the research were supported by scientific analyses carried out according to a
methodological path tested during the several years of surveys in Turkey.[2]
The preliminary in situ investigations were performed by a portable video microscope, Dino Lite AM
413 in order to study in detail the painted surfaces and to choose the best sampling points for the
laboratory analysis.[3]
The micro samples, collected during the 2006-2011 campaigns in Cappadocia, were analysed by
different and complementary laboratory techniques in order to obtain as much information as possible
about the materials and the technique.
The sample cross sections were observed and photographed using a Zeiss Axioskop polarising
microscope equipped with a Zeiss AxioCam digital camera. Cross sections were also studied under UV
lighting, using a Mercury Vapour lamp directly connected to the microscope in order to observe the
materials’ fluorescence, and by Raman microscopy.
The micro-Raman spectrometer used in this case to characterize the pigments and the possible
degradation materials, was a Labram Model from the Jobin Yvon-Horiba with a spatial resolution of
1 µm and with quick detection ability as a result of the CCD detector 1024x256 pixels cooled to -70 °C
by the Peltier effect. The spectral resolution was 5 cm-1. The exciting wavelength was the 632.8 nm red
line of a He-Ne laser.
Infrared spectroscopy was also applied by using a Nicolet Avatar 360 Fourier transform spectrometer.
For each sample 128 scans were recorded in the 4000 to 400 cm-1 spectral range in diffuse reflection
modality (DRIFT) with a resolution of 4 cm-1. Spectral data were collected with OMNIC 8.0 software.
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The Forty Martyrs church at Şahinefendi is characterized by the presence of at least four pictorial
phases put in evidence during the conservation work. The micro stratigraphic analysis of the samples
taken from the Forty Martyrs layer showed a white, sometimes pinkish, plaster: micro-Raman
analysis, performed both on the cross-sections and on the powders, allowed to detect the presence
of calcite, gypsum, anhydrite and calcium oxalate. Gypsum is present in all the mortar with a greater
concentration in the area under the painting layers: probably it was used as a setting layer. Apart the
traditional pigments of the medieval wall paintings, micro-Raman analysis revealed the presence
also of organic dye and lead based compound sometimes characterized by degradation phenomena.
Between the yellow pigments, jarosite was also found, an iron silicate rarely used as painting pigment.
The scientific analysis of the Forty Martyrs church supported the art historians and restorers work to
define the chronology of the painting layers and to study the materials and techniques. The internal
micro stratigraphic analysis and the spectroscopic techniques allowed to found that the mortar in the
Forty Martyrs’ layer was made of lime probably with the addition of organic materials and the painted
layers were applied over a thin setting made of gypsum by a secco or lime technique. The main pigments
are natural earths and ochres, lead based compounds, ultramarine blue and indigo. Some deterioration
phenomena were also observed, probably due to the fires lit in the church during the past years.
The conservative intervention restored the legibility of the pictorial scenes also allowing a valorisation
of the church and of its entire territory.
Figure 1. The Forty Martyrs’
scene at Şahinefendi before and
after the cleaning intervention by
University of Viterbo
Acknowledgements
The survey in Cappadocia is part of a wider project called For a data bank of wall paintings and
mosaics of Asia Minor (4th–15th centuries): images, materials, techniques of execution, directed by
Prof. Dr. Maria Andaloro. The project couldn’t have been carried out without the kind permission
granted by the Turkish Ministry for Culture.
References
[1]
[2]
[3]
[4]
M. Andaloro, Araştirma Sonuçlari Toplantisi. 2009, 26, 187–200.
M. Andaloro, Araştirma Sonuçlari Toplantisi, Denizli. 2010, 27, 517–535.
M. Andaloro, Araştirma Sonuçlari Toplantisi. 2011, 28, 155–172.
C. Pelosi, U. Santamaria, G. Agresti, F. Castro, D. Lotti, P. Pogliani, Arkeometri Sonuclari Toplantisi. 2010,
25, 535–552.
[5] C. Pelosi, G. Agresti, M. Andaloro, P. Baraldi, P. Pogliani, U. Santamaria, e-Preservation Science, accepted
6. 2. 2013, in press.
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Vibrational characterization of the new gemstone Pezzottaite
Erica Lambruschi,1* Danilo Bersani,1 Pier Paolo Lottici,1 Giacomo Diego Gatta,2,3
Ilaria Adamo3
Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Parma, Parma, Italy,
+39 0521905239, [email protected].
2
Dipartimento di Scienze della Terra, Università degli Studi di Milano, Milano, Italy
3
CNR-Istituto per la Dinamica dei Processi Ambientali, Milano, Italy
1
Pezzottaite is a rare Cs-bearing mineral with ideal composition Cs(Be2Li)Al2Si6O18, discovered
in November 2002. Pezzottaite is probably the only new mineral species with some relevance in
gemology, thanks to its optical properties, rarity and beauty.
It is considered as a member of the “beryl group”, along with beryl sensu-scricto (Be3Al2Si6O18), bazzite
(Be3Sc2Si6O18), stoppaniite (Be3Fe2Si6O18) and indialite (Mg2Al3(AlSi5O18)).
The chemical composition and the spectroscopic features of pezzottaite from Ambatovita (central
Madagascar) and a Cs-rich beryl from Monte Capanne (Isolad’Elba, Italy) were investigated by standard
gemmological analysis, electron microprobe analysis in wavelength dispersive mode (EMPA-WDS),
X-ray diffraction and micro-Raman spectroscopy.
The density and the refractive index of pezzottaite were found to be higher than those of beryl due to
the entrance of a large amount of alkali. However, an unambiguous distinction between pezzottaite and
Cs-rich beryl cannot be done only on the basis of density and optical properties.
Pezzottaite and Cs-rich beryl are usually distinguished on the basis of chemical analysis, considering
a conventional upper-limit of caesium in Cs-rich beryl of Cs2O ~ 9 wt%, or by X-ray diffraction, as
pezzottaite has different symmetry. In any case, the discrimination is not easy and requires advanced
and expensive techniques.
Chemical analysis of our samples showed an high amount of cesium (Cs2O 12.91 wt%) for pezzottaite,
while the Cs-beryl has 1.27 wt%.
Figure 1. Raman spectra of pezzottaite (above) and Cs-
Figure 2. Raman spectra of pezzottaite (above) and Cs-beryl
beryl (below) in the region 100-1,200 cm .
(below) in the region 3,500-3,650 cm-1.
-1
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The crystal structure of the samples has been investigated through X-ray diffraction. The pezzottaite
has a trigonal symmetry (space group R-3c, with a~15.9 and c~27.8 Å), while beryl is hexagonal
(space group P6/mcc, with a~9.2 and c~9.2 Å). The increase of cell parameters is due to the entrance
of lithium,that replaces beryllium in the tethaedra. The replacement causes a positive charge deficit
neutralized by cesium in the channels.
The samples of pezzottaite and Cs-rich beryl were investigated by micro-Raman spectroscopy, a nondestructive and rapid tool of investigation. The un-polarized Raman spectrum of pezzottaite over the
extended region 100-3,650 cm-1 was collected for the first time, and compared with the spectrum of
a Cs-beryl (Figure 1 and 2). In particular, Cs-beryl has showed only an intense peak at 3604 cm-1,
ascribable to H2O stretching vibrations. On the other hand, two weak Raman bands at 3,591 and 3,545
cm-1,ascribable to the fundamental H2O or OH stretching vibrations respectively, were observed, despite
the mineral should be nominally anhydrous. The Raman spectroscopy was useful to understand the
type of water (type “I” or type “II”) and then to evaluate presence of alkali in the channels.
In addition, the Raman spectrum of pezzottaite shows two intense and characteristic bands at 110-112
cm-1 and 1,100 cm-1, which are not present in the beryl spectrum (Figure 1).
Even if the true nature of the two bands is not completely understood, Raman spectroscopy appears to
be a promising and inexpensive tool for a quicker identification of pezzottaite.
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Preliminary investigations by Raman microscopy, FTIR-ATR
and ESEM of wall paintings from the tomb of Amenemonet (TT277),
Qurnet Murai necropolis, Luxor, Egypt
Mohamed Abd El Hady 1*, Hussein Marey Mahmoud2
Department of Conservation, Faculty of Archaeology, Cairo University, Giza, Egypt,
+386 1 2343 118, [email protected].
2
Department of Conservation, Faculty of Archaeology, Cairo University, Egypt
1
The present paper reports preliminary results obtained from the application of different analytical
techniques used to characterize samples of wall paintings from the tomb of Amenemonet (TT277) (the
19th dynasty, c. 1298-1187 BC) , Qurnet Murai necropolis, Luxor, Egypt. The samples were analyzed
by optical microscopy (OM), environmental scanning electron microscopy (ESEM) coupled with an
energy dispersive X-ray analysis system (EDAX), Raman microscopy and Fourier transform infrared
spectroscopy equipped with an attenuated total reflectance detector (FTIR-ATR). Thanks to the
microscopic unit attached to Raman instrument, spectra were recorded on individual grains in the
samples. The analyses on the samples have been undertaken on the rough samples without any kind
of preparation. The chromatic palette used in the tomb was identified as: Egyptian blue (cuprorivaite),
red ochre (haematite), yellow ochre (goethite) and carbon black (from a vegetable origin). A green
tonality was obtained through a mixture of Egyptian blue and yellow ochre. The analysis showed
that the preparation layer is almost made of pure gypsum. The Raman spectrum recorded on the red
pigment sample (see Fig. 1) represents typical peaks of haematite (α-Fe2O3) at 226, 298, 417 and 614
cm–1 (Goodall et al. 2007; Marey Mahmoud, 2011). Moreover, the strong band at 417cm–1 indicates a
well-crystallised haematite. The Raman spectrum of the yellow pigment sample shows bands at 395,
305 and 557 cm–1 are for goethite (α-FeOOH). Several amounts of titanium dioxide phase anatase were
detected in the yellow pigment samples which can be a contaminant in natural iron oxide deposits.
EDAX microanalysis obtained on the red and yellow pigment samples shows the presence of signal
of iron together with minor amounts of Al and Si. The later ones could be due to the existence of
an aluminosilicate material (e.g. clay minerals which could be primary accessory minerals in ochre
pigments). In the case of blue pigment samples, the pigment fluoresced very strongly when it was
excited at 785 nm. For this, the identification of the blue pigment was based mainly on ESEM-EDAX
Figure 1. ESEM image and µ-Raman spectrum
obtained on the red pigment sample.
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and FTIR-ATR analyses which indeed confirm the presence of cuprorivaite. The FTIR-ATR spectrum
recorded on the pigment shows characteristic peaks in the region 1000 and 1050 cm−1 are attributed to
Si−O−Si stretching vibrations.
In this region, Egyptian blue gives raise to a typical triplet bands, medium intensity bands at 1003,
1049 cm−1 and low intensity bands at 1157 and 1215 cm−1. The Raman spectrum recorded on the black
pigment contains two characteristic broad bands for carbon black centred at 1345 and 1583 cm–1. The
Raman analyses detected no band at 960 cm–1, the wave number of the stretching of the phosphate ion
[PO4]3–, so that the presence of ivory black and bone black may be excluded (Ospitali et al. 2006). This
indicates that the carbon was obtained from a vegetable origin. FTIR-ATR analysis on the pigment
samples showed the spectra are consistent with a proteinaceous material (amide II vibration at 1541
and 1578 cm–1). The absence of carbonyl bands at c. 1730 cm–1 suggests that the protein may be the
animal glue. In most of samples, the content of animal glue was not confirmed because the amide I and
II bands are masked by the broad bands of calcium sulphate, oxalate and carbonate.
Further analysis using gas chromatography mass spectrometry (GC/MS) will be useful to identify
the proteins in the sample. In conclusion, the obtained results will be discussed and compared with
previous finds from ancient Egyptian monuments dating back to the same period.
References
[1] R. A. Goodall, J. Hall, H. G. M. Edwards, R. J. Sharer, R. Viel, P. M. Fredericks, Journal of Archaeological
Science. 2007, 34(4), 666–673.
[2] H. Marey Mahmoud, Mediterranean Archaeology and Archaeometry. 2011, 11(1), 99–106.
[3] F. Ospitali, D. C. Smith, M. Lorblanchet, J. of Raman Spectrosc. 2006, 37, 1063–1071.
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Physico-chemical characteristics of Predynastic pottery objects
from Maadi Egypt
Mohamed Abd El Hady,1 A. Abdel-Motelib,2 Rabea Radi,3 Shaimaa Sayed4*
Faculty of Archaeology, Cairo University, Giza, Egypt, +0201064945338, [email protected]
Geology Department, Faculty of Science, Cairo University, Giza, Egypt, +0201223314921,
[email protected]
3
Ministry state of Antiquities, Giza, Egypt, +0201002079624, [email protected]
4
Ministry state of Antiquities, Egypt, +0201007256560, [email protected]
1
2
Pottery manufacture is considered one of the oldest techniques practiced by human beings all over the
world through ages. This is why that the archeological missions working in the ancient sites found a lot
of pottery objects of different kinds and types which were processed by different techniques.
The archeological pottery objects discovered in Maadi Sites in Egypt are mostly dating back to
Predynastic Period about 3500 BC (Naqada Culture, Early Bronze Age). These objects are very rare
either in Egypt or in international museums but they are unique and of great archaeological value.
The chosen pottery objects were investigated and analyzed using polarized microscope, XRD analysis,
and SEM techniques. The present research focuses on the processes and techniques of this type of
pottery and illustrates its physio-chemical properties which varied greatly due to heterogeneity of the
raw materials used in manufacturing as revealed from the obtained results. Moreover the results show
that the incompletely fired samples contain clays, iron and titanium oxides, carbonates, quartz silt
and organic materials while the completely fired samples are composed of chlorite, Meta kaolinite and
quartz.
On the other hand the present research focuses the light on identifying the deterioration products
presenting in these archaeological objects. The obtained results showed that these objects seriously
deteriorated due to due to physico-chemical and biological deterioration factors.
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Raman Database of Corrosion Products as a powerful tool
in art and archaeology
Serena Campodonico,1,2* Giorgia Ghiara,1 Paolo Piccardo,1
Maria Maddalena Carnasciali1,2
University of Genoa, Department of Chemistry and Industrial Chemistry (DCCI), Italy,
+39 010 3536088, +39 010 3538733, [email protected]
2
Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM),
Firenze, Italy
1
The employment of Raman spectroscopy is well known in the field of art and archaeology,[1] being this
non-destructive type of analysis also practicable with portable instruments if necessary. It is in fact
known that elemental analysis cannot provide a precise and univocal answer in the detection of organic
and inorganic compounds and many other analytical techniques (as X-Ray Powder Diffraction – XRD
– for instance) are destructive and needing a sample taking, that for artistic and archeological objects
is not frequently possible to obtain.
Even though significant progress has been made in the construction of Raman spectral databases
of historical materials, many of these ‘reference’ spectra come from isolated incidents belonging to
modern materials which do not focus their attention specifically on corrosion products. Accordingly,
even if literature spectra represent a good starting point for the identification of unknown phases, the
presented research mainly focuses on the collection of different spectra of corrosion products of a
restricted area of materials (metallic materials) in order to help researcher and conservator scientists
in their work of characterization and study of deterioration mechanisms and of conservative conditions
of artistic and archaeological materials.
The main purpose of the research is to compare real cases coming from different scientific contexts,
from cultural heritage to industrial applications (archaeological, ethnological, historical. modern,
industrial), with standard samples (powders and minerals) and to realize a complete and exhaustive
Raman library in the field of corrosion, where this tool has not been recognized as powerful as it possibly
could become, yet. For example, the specific and non-destructive identification of minute quantities
of material can provide the archaeologist invaluable information regarding an artefact including its
authenticity, provenance, manufacturing technology, trade patterns, state of preservation and in some
cases, approximate age.
By the analysis of minerals, powders, artistic and archaeological metallic artifacts it was also possible
to give a direct proof of corrosive mechanisms and an immediate term of comparison since the
suitability of the modern reference spectra for identifying aged samples has not been fully tested. For
instance, samples found in archaeological context are likely to be natural products of inherent chemical
variability which have undergone traditional processing, subsequent ageing and possible degradation
and appearing variable in stoichiometry their Raman spectra are likely to reflect this variability - e.g. a
mixture of tin and copper oxides forming on the surface of tin bronze objects.
Following this line, part of the research aim was also to better understand all the possible differences in
spectral signal of as many real cases as possible, homemade powders and selected minerals associated
to all kind of corrosion mechanisms involving metallic artifacts by modifying certain parameters as
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corrosion products status, growth degree, flaws and defects, mixed forms, etc…
Moreover the choice of the laser excitation source has to be taken into account each time a spectrum
is obtained. It is possible in fact not being able to identify the same corrosion product on a specimen
surface due to the change of laser wavelenght applied. The akaganeite spectrum shown in Figure 1
emphasizes the difficulties in its identification by comparisons to literature spectra which differ in
relative intensities using a different excitation source. Each time such problems occur the possibility of
using a Raman database of known corrosion products offers more reliable answers.
Figure 1. Raman spectrum of Akaganeite
(β-FeOOH), corrosion product rarely found on iron
artifacts.
Analyses were undertaken at the Department of Chemistry and Industrial Chemistry (DCCI) with a
Renishaw Raman System 2000 coupled with an optical microscope and a red He-Ne laser applying
same laser parameters as gain, power, accumulations.
The obtained database will soon be available on-line and shared by all research users.
References
[1] L. Bellot-Gurlet, S. Pagès-Camagna, C. Coupry. J. of Raman Spectrosc. 2006, 37, 962–965.
.
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Micro-Raman as a powerful non-destructive technique to
characterize ethonological objects from D’Albertis Castle Museum
of World Cultures in Genova
Serena Campodonico,1,2* Giorgia Ghiara,1
Maria Maddalena Carnasciali,1,2 Camilla De Palma3
University of Genova, Department of Chemistry and Industrial Chemistry (DCCI), Italy,
[email protected]
2
Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM),
Firenze, Italy
3
D’Albertis Castle Museum of World Cultures, Genova, Italy
1
In recent periods an awakened interest is grown on non - invasive techniques employed in the field
of art and archaeology – mainly focusing on the identification of pigments, binding media, etc…or on
the characterization of degradation processes of objects showing some cultural or ethnological value.
Characterization of cultural heritage artifacts by the use of non - invasive procedures has widely been
discussed, as shown in many publications and books. Energy Dispersive or Wavelength Dispersive X Ray Fluorescence (EDXRF or WDXRF) measurements have often been associated to more traditional
sample-requiring analyses – e.g. X-Ray Diffraction (XRD) or Scanning Electron Microscopy coupled
with Energy Dispersive X-Ray Spectroscopy (SEM-EDXS) – in order to gain preliminary compositional
information.[1] Yet only in recent times Raman spectroscopy has roused a wide range of interest because
of his great potential as non-destructive technique in the field of diagnostics.[2]
The D’Albertis Castle Museum of World Cultures in Genoa represents a wonderful example of
ethnological collection. A large number of different types of objects - of unknown nature and/or
composition -, have been collected by the Captain D’Albertis during its journeys across lands and seas
all around the world between the end of the XIX century and the beginning of the XX century. This
remarkable collection, like a “cabinet of curiosities”, gave us the possibility to discover artworks of great
interest from the conservative point of view. Since the possibility to analyze them has been limited
under the sine qua non condition of non-destructive analysis without sample taking, the employment
of microRaman spectroscopy has been considered perfect for the research.
MicroRaman technique resulted as a powerful tool, coupled also with a p-XRF instrument for the
material characterization of a selection of small metal objects taken from the collection inside the
Sala Colombiana of the museum. These metal objects have been chosen for their different provenance,
date, type of metal/alloy, use, conservation status, shape and color. Analyses have been carried out in
the laboratories of the Department of Chemistry and Industrial Chemistry (DCCI) with a Renishaw
Raman System 2000 coupled with an optical microscope and a red He-Ne laser – applying changes in
laser parameters e.g. gain, power, accumulations.
The obtained results not only allowed us to identify metal composition – e.g. an unknown bracelet
constituted by a metallic twist of brass and iron with copper plates was identified by detecting iron and
copper corrosion products – but with the help of this invaluable technique it was possible to investigate
corrosion products depositing on the object surface and correlating them directly to the environmental
conditions they were exposed to – e.g. wet and dry cycles, marine atmospheres, burial.
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Figure 1. LOM and Stereo micrographs of an African bracelet
Figure 2. From the analysis it was possible to see the heterogeneous
from Rhodesia, Zimbabwe.
nature of corrosion products, which gave information on the
elemental composition of the bracelet itself.
Acknowledgements
The authors would like to thank the Soprintendenza ai Beni Artistici e Archeologici of Genova and
the D’Albertis Castle Museum of World Cultures for giving the possibility to undertake this research
project.
References
[1] V. Desnica, K. Škarić, D. Jembrih-Simbuerger, S. Fazinić, M. Jakšić, D. Mudronja, Appl. Phys. A. 2008, 92(1),
19–23.
[2] L. Bellot-Gurlet, S. Pagès-Camagna, C. Coupry, J. of Raman Spectrosc. 2006, 37, 962–965.
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Micro ATR-IR study of pollutions affecting radiocarbon dating
of ancient Egyptian mummies
Céline Paris,1 Anita Quiles,2,3* Ludovic Bellot-Gurlet,1 Emmanuelle DelquéKolič,3 Cathy Vieillescazes,4 Matthieu Ménager,4 Clothilde Comby-Zerbino,3
Karine Madrigal5
LADIR UMR 7075 CNRS-UPMC, Université Pierre et Marie Curie, Paris, France,
[email protected]
2
LSCE, Bât. 12, avenue de la Terrasse, Gif-sur-Yvette, France, [email protected]
3
LMC14 – UMS 2572 – CEA de Saclay, Gif-sur-Yvette, France
4
Université d’Avignon et des Pays de Vaucluse, IMBE, Avignon, France
5
Musée des Confluences de Lyon, Lyon, France
1
In the frame of a study on the establishement of an absolute chronology for ancient Egypt[1] the
Laboratoire de Mesure du Carbone 14 has dated by 14C textiles and body fragments of Egyptian
mummies conserved at the Musée des Confluences de Lyon (France). Ages older than expected were
obtained for two mummies. Further examinations let suspecting some late rituals possibly involving
the use of bitumen which could explain the aging of 14C results by fossil carbon. As the use of bitumen
could have been used for mummification rituals in the graeco-roman period, the establishment of
easily implemented procedure for detection and removal of aging pollution will offer new perspectives
to ensure radiocarbon dating in these contexts.
Complementary analyses were then performed to look for bitumen identification; in parallel some
specific procedures for sample preparation were evaluated to remove fossil organic pollution before
dating.
Because of its flexible implementation, its low requirement in sample amount and sensitivity for
organics, micro-ATR IR spectroscopy (micro-Attenuated Total Reflexion Infrared) was privileged in
this study to detect and identify aging’s contaminant. In order to facilitate organics identification,
we focused on the study of mummy’s strips made of linen. A first study of “contaminated” and “none
contaminated” linen samples (in respect to their radiocarbon age) underline the presence of a “lipidic”
organic substance. It is characterised by a specific profile of the CH massif and an acid group (with a
band at 1707 cm-1). A comparison with modern test samples imbibed by bitumen of Judea provides a
very similar vibrational signature.
On the other hand, various protocols of ultrasound-assisted organic component extraction were
carried out on a set of modern lin fabric impregnated with bitumen. Micro ATR-IR analyses and 14C
measurements were then performed to evaluate the sample purification.
The efficiency validation will allow proposing a pre-treatment procedure for samples in which aging
pollutions could be suspected by a preliminary spectroscopic analysis.
References
[1] A. Quiles, E. Aubourg, B. Berthier, E. Delque-Količ, G. Pierrat-Bonnefois, M. W. Dee, G. Andreu-Lanoë, C.
Bronk Ramsey, C. Moreau. J. of Archaeological Science. 2013, 40, 423.
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Raman Scanning of Biblical Period Ostraca
Arie Shaus,1* Barak Sober,2 Omer Tzang,3 Zvi Ioffe,4 Ori Cheshnovsky,5 Israel
Finkelstein,6 Eliezer Piasetzky7
The Department of Applied Mathematics, Tel Aviv University, [email protected]
The Department of Applied Mathematics, Tel Aviv University, [email protected]
3
School of Chemistry, Tel Aviv University. [email protected]
4
School of Chemistry, Tel Aviv University.
5
School of Chemistry, Tel Aviv University, [email protected]
6
The Jacob M. Alkow Department of Archaeology and Ancient Near Eastern Civilizations, Tel Aviv
University, ﬁ[email protected]
7
The Sackler School of Physics and Astronomy, Tel Aviv University, [email protected]
1
2
The ink of ostraca inscriptions tends to fade significantly over time. Therefore, acquiring the most legible
image of an ostracon promptly after the excavation is crucial for its documentation. Unfortunately,
existing image acquisition techniques were not able to cope with the challenging medium in a satisfying
manner. Preliminary experimentation showed that Raman-based methods bear the potential for ink
identification. Consequently, a novel Raman scanning device suitable for this task was constructed
and tested on ostracon from Horvat ‘Uza in the Beersheba Valley. The mapping was based on new
computational peak-finding tools, producing a binary inscription image. Our experiments showed the
promise in these techniques.
Acknowledgements
The research leading to these results received funding from the F.I.R.S.T. (Bikura) Individual Grant
no. 644/08. The research was also partially funded by the European Research Council under the
European Community’s Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no.
229418. This study was also supported by a generous donation of Mr. Jacques Chahine, made through
the French Friends of Tel Aviv University. Arie Shaus is grateful to the Azrieli Foundation for the award
of an Azrieli Fellowship.
Figure 1. a.) Raman complex diagram: The laser (red) was collimated, reflected by a
prism onto the objective lens. The scattered light (pink) was collected and passed through a
beam splitter (BS) and a notch filter (NF). Light that travelled through the notch filter was
collimated by a tube lens on to an optical fiber and entered the spectrograph. b.) General
drawing of the Raman microscope system.
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Figure 2. Example of Horvat ‘Uza ostracon scan a.) Area of interest b.) Overlaid Raman scan results c.) Scan results after post-processing
(median filter).
References
[1] S. Faigenbaum, B. Sober, A. Shaus, M. Moinester, E. Piasetzky, E. Bearman, M. Cordonsky, Finkelstein I.
“Multispectral Images of Ostraca: Acquisition and Analysis”. J. of Archaeological Science, 2012, 93(12),
3581–3590.
[2] I. Finkelstein, E. Boaretto, S. Ben Dor Evian, D. Cabanes, M. Cabanes, A. Eliyahu, S. Faigenbaum, Y. Gadot,
D. Langgut, M. Martin, M. Meiri, D. Namdar, L. Sapir-Hen, R. Shahack-Gross, A. Shaus, B. Sober, M.
Tofollo, N. Yahalom-Mack, L. Zapassky, S. Weiner, “Reconstructing Ancient Israel: Integrating Macro- and
Micro-archaeology”, Hebrew Bible and Ancient Israel. 2012, 1, 133–150.
[3] B. W. Porter, R. J. Speakman, “Reading Moabite Pigments with Laser Ablation ICP-MS: A New
Arcbaeometric Technique for Near Eastern Archaeology”, Near Eastern Archaeology. 2008, 71(14), 238–
242.
[4] O. Tzang, K. Kfir, E. Flaxer, O. Cheshnovsky, S. Einav, “Detection of Microcalcification in Tissue by Raman
Spectroscopy”, Cardiovascular Engineering and Technology. 2011, 2(3), 228–233.
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Analyses of pigments from 4th century B.C. the Shushmanets tombs
in Bulgaria
Cristina Aibéo,1 Stefan Simon,1 Diana Georgova,2 Veska Kameranova,
Ivelina Pavlova, Angel Pavlov
Rathgen Research Laboratory – National Museums Berlin, Germany,
2
National Institute of Archaeology with Museum – BAS, Sofia, Bulgaria, +359 2 988 24 06
3
CRA – Centre for Restoration of Art Works, Sofia, Bulgaria, +359 887262718
1
The Thracian tomb-temple under the “Shoushmanets” tumulus was discovered in 1996. The tumulus
belongs to the huge necropolis of the Odryain kingdom in the Kazanlak valley and dates back to the
4th century BC.
The tomb is one of the most representative works of the Thracian architecture. It is typical
for the South Thracian lands tholos type, but is unique with its architectural solutions.
It is built of large, well-formed stone blocks and consists of a wide dromos, an antechamber with
a semi-cylindrical vault, supported by a Doric column with Ionic capital and a circular main
chamber with a small bed on the opposite to the entrance side. Although the tholos tomb is the most
characteristic architectural type in Southern Thrace, the tomb under Shushmanets is unique with
the central column in the burial chamber ending with a large disk as a Sun symbol. It is the only
Balkan example of a series of Megalithic and Early Iron Age tombs with central column known from
the Mediterranean world - from Menorca to the Etruscan territories. The main chamber is decorated
with semi-columns in Doric style and vertical flutes. The floors and the walls were plastered in white
in several layers. The discovery during restoration works of an earlier omphalos (altar), plastered on
the floor of the central chamber, the sacrifices in the antechamber of four horses and two dogs, as well
as the small bed in the chamber, suitable rather for sitting, confirm its function as tomb-temple, in
which periodically different mysteries, connected with the Orphic mysteries and beliefs in the astral
immortality had been performed.
The interdisciplinary approaches are the only possibility after the archaeological research to throw new
light on the story of the tomb temple, on its function, and on the character of the mysteries performed
in it.
The characterisation of mortars[1] was already published; the present paper is about the characterisation
of the tomb pigments and its comparison with similar constructions from the same period.[2] The nondestructive technique of Raman spectroscopy was used for this purpose.
Spectra were acquired with a Horiba XploRa Raman-Microscope, fitted with lasers of wavelength 532
nm, 638 nm and 785 nm. The power of each laser was 25 mW (532 nm), 24 mW (638 nm) and 90 mW
(785 nm). The maximal spatial resolution was 1 µm. In the spectra, Raman shifts are given in cm-1.
References [1] Eugenia Tarassova et al., National Conference with international participation “GEOSCIENCES 2012”,
BULGARIAN GEOLOGICAL SOCIETY, 2012, 157–158.
[2] Koinova-Arnaudova, Lorinka, K. Krusstev, M. Enev, L. Kinova, I. Penev, The Thracian Tomb near Sveshtary
village, The conservation of cultural heritage for sustainable development, ed. European Communities,
ICSC, 2003, 291–295.
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Raman Spectroscopic Study of the Formation of Fossil Resins
Analogs
Oscar R. Montoro,1* Mercedes Taravillo,1 Margarita San Andrés,2 José Manuel
de la Roja,2 Alejandro F. Barrero,3 Pilar Arteaga,3 Valentín G. Baonza1
MALTA-Consolider Team & QUIMAPRES Team, Departamento de Química Física I, Facultad de
Ciencias Químicas, Universidad Complutense de Madrid, Spain, +34 91 394 42 62, ormontoro@quim.
ucm.es
2
Universidad Complutense, Facultad de Bellas Artes, Dpto. de Pintura-Restauración, Madrid, Spain,
3
Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Granada, Spain,
1
Fossils resins are gemstones of organic nature that have survived until ours days. The vast majority of
fossil resins derives from natural terpene-based polymers, and therefore has an organic origin. These
are classified into five classes, of which the most important is called Class I, that it is composed by
monomers of labdanics family (a type of diterpene) polymerized, primarily of polymerized communic
acids [1,2], whose chemical structures are shown in Figure 1.
The reaction processes that have taken place throughout the ages until formation of fossil resins are
complex and little studied, therefore they are poorly understood. Existing studies have focused on the
possible high temperature polymerization in the family of communic acids, which are precursors for a
large majority of Class Ia fossil resins.[3]
Figure 1. Communic acids. R = -COOH; trans-, cis-, mirceo-.
The main purpose of this work is to provide spectroscopic evidences of possible chemical pathways
that took place in the formation of fossil resins, through the reactivity of pure communic acids at
different temperatures. We shall focus here on trans-, cis- and mirceo- communic acids. The maturing
reactions proposed in the literature are mainly polymerizations between the conjugated double bonds
and subsequently internal molecular reactions in the initial polymer formation.
The samples were characterized by a confocal micro-Raman spectrometer (BWTEK VoyageTM BWS435532SY) coupled to an Olympus BX51 microscope. Raman spectra were taken by using a 532.0 nm laser
line. Our studies for these pure compounds were completed with Fourier Transform infrared (FTIR),
ATR-FTIR and differential scanning calorimetry measurements.
We have performed our study in each pure component separately. Figure 2 depicts some Raman spectra
measured at selected temperatures for the trans-communic acid. An increase in fluorescence of the
sample is observed above the melting temperature of these acids (around 170–180 °C in the case of
trans-communic acid), which results in a significant change of color of the initial mixture (white to
yellow-amber for the recovered sample after heating cycle). We will analyze the temperature-induced
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changes in the different Raman features and the possible reactivity that has taken place.
In addition, we have focused in the spectral regions of the C-H stretches and bending fingerprint,
since this is key spectral region for understanding the formation of fossil resins. Such features usually
give information of the geographical origin and antiquity of the specimens, and they may assist to
distinguish real fossil resins from imitations. Finally, the spectroscopic results have been compared
with a number of fossil resins of different geological dating.
Figure 2. Raman spectra of trans-communic acids
at selected temperatures. λ exc = 532 nm.
Acknowledgement
This work has been funded by the Spanish Ministry of Science and Innovation under Projects CTQ201020831, CTQ2012-38599-C02-02 and MALTA-Consolider Ingenio 2010(CSD2007–00045). The
authors are also grateful to the Science and Technology of Heritage Conservation Laboratory Network
(RedLabPat), CEI, Moncloa Campus (UCM-UPM) and Comunidad de Madrid and EU through the
QUIMAPRES-S2009/PPQ-1551 program.
References
[1] K. B. Anderson, R. E. Winans, R. E Botto, Organic Geochemistry. 1992, 18, 829–841.
[2] A. F. Barrero, M. M. Herrador, P. Arteaga, J. F. Arteaga, Molecules. 2012, 17, 1448–1467.
[3] R. M. Carman, D. E. Cowley, R.A. Marty, Australian Journal of Chemistry. 1970, 23, 1655–1665.
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Pigments from Templo Pintado (Pachacamac, Perú) investigated by
Raman Microscopy
Dalva Lúcia Araújo de Faria,1*Gianella Pacheco,2
Denise Pozzi-Escot,2 Marta S. Maier,3 Valeria Careaga3
Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil,
2
Museo de sitio de Pachacamac, Ministerio de Cultura, Lima Perú, [email protected],
[email protected].
3
UMYMFOR and Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales,
Universidad de Buenos Aires. Buenos Aires, Argentina, [email protected],
[email protected]
1
Pachacamac is a complex and vast archaeological site on the coast of Perú, 31 km south from Lima
(Lat.12° 15’ 29” South Long. 76° 54’ 00” West). Its origin goes back to 200 CE and was taken over from
the Ychma by the Incas around 1470 CE. As a religious and pilgrimage site, among the most significant
buildings are the Templo Pintado (Painted Temple) and Templo del Sol (Temple of the Sun). The former
is a 50 m high and 100 m wide adobe pyramid, with 3 sides made of a succession of giant steps (1 m
high); the fronts of such staggered building are decorated with people, plants, birds and fish paintings,
Figure 1. Painted wall at Templo Pintado, showing severe deterioration (left) and adobe fragment with
a bluish-green paint (right).
colored in red, yellow and bluish-green mineral pigments, outlined in black1(Fig. 1). The current efforts
in the preservation of such magnificent archaeological site demand a better understanding on the
materials and techniques originally employed. This work reports the results of pigment analysis using
Raman Microscopy and XRD.
The investigated samples were 5 painted adobe fragments from Templo Pintado (north wall) and 4
minerals collected in quarries at the site area (Table 1). The painted fragments were investigated by
Raman Microscopy (632.8 nm, 785 nm and 1064 nm excitation) and the reference minerals were also
characterized by XRD.
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Table 1. Samples identification and description
Sample ID
Sample Description
TP-029a
Painted fragment (several layers): red, pale yellow and bluish-green
TP-029b
Painted fragment: red and orange pigments
TP-029c
Painted fragment: red paint
TP-029d
Painted fragment: bluish-green paint with black trace
TP-029e
Stone bluish-green fragment with porous and irregular surface
MC1
Yellow pigment from quarry
MC2
Red pigment from quarry
MC3
Pale yellow pigment from quarry
MC4
Pale red pigment from quarry
The main issues to be addressed in the present investigation are: (i) the minerals from the quarries
(MC1 to MC4) and the pigments in the painted fragments (TP-029a to TP-029e) are the same? (ii) the
bluish-green pigment on sample TP-029d and TP-029e are the same? (iii) the black colored pigment
in sample TP-029d is carbon? (iv) which organic binders, if any, were used to prepare the paintings?
An extensive Raman Microscopy investigation revealed that the red pigments were hematite2 (α-Fe2O3)
in both MC and TP samples, but bands assigned to α-quartz (465 cm-1) and magnesium sulfate (main
band at 1006 cm-1) were also identified. Curiously, XRD did not show the presence of any crystalline
compound (including hematite) in none of the red samples (MC2 and MC4). Cinnabar was not
detected. Black pigment in TP-029d is carbon (broad bands at ca.1360 and 1580 cm-1), although in
a much smaller extension, magnetite (Fe3O4)was also identified; it is very likely that the latter is a
contamination, considering the minerals used in the paint. Concerning the bluish-green pigment,
despite the luminescent background it was possible to identify celadonite (K(Mg,Fe2+)Fe3+(Si4O10)(OH)2)
in both painted adobe and stone fragment, using Raman Microscopy and XRD. Furthermore, in the
bluish area of the adobe fragment, a very small (300-400 µm) piece of bright blue bird feather was
found.
In conclusion, Raman Microscopy and XRD were used to show that the minerals collected in quarries
at the Pachacamac site and the paints on the adobe fragments are mostly silicates; in the case of the
red pigment, hematite was identified by Raman Microscopy but not by XRD, indicating a low degree
of crystallinity. It is thus very likely that the pigments used in Templo Pintado were from the local
quarries. It was also shown that the bluish-green pigment in sample TP-029d and TP-029e are the
same and corresponds to celadonite. A small fragment of blue bird feather suggests that the walls
decorations had more than mineral pigments. Finally, the pigment in the black trace in sample TP029d is carbon.
References
[1] J. C. Muelle, R. Wells, Revista del MuseoNacional. 1939, 8, 265.
[2] D. L. A. de Faria, S. Venâncio Silva, M.n Spectroscopy. 2012, 43, 1811–1816.
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Lithic tools raw materials recognition by Raman spectroscopy of
Palaeolitihic artifacts
Sonia Murcia-Mascaros,1*Clodoaldo Roldan,1 Valentin Villaverde,2
Aleix Eixea,2 Jorgelina Carballo1
1
Materials Science Institute, University of Valencia, ICMUV, Paterna, Valencia, Spain,
[email protected]
2
Departamento de Prehistoria y Arqueología, Universityof Valencia, Spain
A preliminary characterisation of the lithic raw-materials found in levels I-III of the Middle Paleolithic
site of Abrigo de la Quebrada (Valencia, Spain) is reported. The artifacts were excavated in the field
seasons of 2004 and 2007, have already been the object of a preliminary technological assessment and
their analysis has been preceded by a survey of local procurement sources, carried out in 2008. We
recognized six raw-material categories by means of a macroscopic study.[1]
A representative set of these lithic tools has been nondestructively investigated by means of Raman
spectroscopy. The characterization of the mineral composition allows the assessment of the resource
catchments and mobility patterns of the human groups that used the shelter at this time.[2]
It was found that a-quartz crystallites, in association with the silica mineral moganite and the free
Si–O vibrations of non-bridging Si–OH from silanole, are present on raw materials and could be used
to distinctive fingerprint in these chert samples.[3]
Figure 1. Lithictoolsfromthe Abrigo de la Quebrada,
Chelva, Valencia (middlePalaeolithic).
References
[1] V. Eixea, V. Villaverde, J. Zilhão, Trabajos de Prehistoria, 2011, 68, 65.
[2] V. Hernández, S. Jorge-Villar, C. Capel Ferrón, F. J. Medianero, J. Ramos, G.C. Weniger, S. Domínguez-Bella,
J. Linstaedter, P. Cantalejo, M. Espejoi, J. J. Durán Valsero, J. RamanSpectrosc. 2012, 43, 1651.
[3] P. Schmidt, L. Bellot-Gurlet, A. Slodczyk, F. Frohlich, PhysChem Minerals. 2012, 39, 455.
183
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Raman characterization on historical mortar. Crossing data with
XRD and Color Measurements
Dorotea Fontana,1,2* Anna Maria Gueli,1 Giuseppe Stella,3,4 Sebastiano Olindo
Troja,1 Maria Brai,2 Jorge Dinis,4 Luis Almeida,3 Lilia Basílio,3 Miguel Almeida3
PH3DRA Laboratories (PHysics for Dating Diagnostic Dosimetry Research and Applications),
Dipartimento di Fisica e Astronomia, Università di Catania & INFN Sezione di Catania, Catania, Italy,
[email protected]
2
Laboratorio di Fisica e Tecnologie relative – UniNetLab, Dipartimento di Fisica e Chimica, Università
degli Studi di Palermo, Palermo, Italy
3
iDryas / Dryas Octopetala, Coimbra, Portugal
4
Earth Sciences Dep., Faculty of Science and Technology, University of Coimbra, IMAR-CMA,
Coimbra, Portugal
1
Raman spectroscopy is becoming a popular technique to classify samples of building materials
such as mortars by molecular analysis, thus providing invaluable information about these material’s
composition and manufacture techniques, relevant for preservation operations and/or dating and
technical studies.[1]
Carbonation takes place in building materials when atmospheric CO2 reacts with Ca2+ present in the pore
solution. Of the three crystallized forms of calcium carbonate, calcite is the most thermodynamically
stable. Raman spectroscopy is a very useful technique for distinguishing between calcite, aragonite and
vaterite.[2]
In the present study, micro-Raman techniques are used for the first time to establish the existence
of various forms of calcium carbonate in lime mortar collected from the Convento de S. Francisco
(Coimbra, Portugal). Measurements were carried out using a micro-Raman system equipped with 542
nm and 785 nm laser sources excitation wavelenghts.
Raman results were crossed with macroscopic interpretation of the building’s structure, mineralogical
characterization by XRD and colorimetric data.
The mineralogical characterization was based on X-ray diffraction (XRD) with a Philips X’Pert Pro
PW3710 diffractometer equipped with a with CuK_ radiation, operating at 40 kV and 20 mA.
An experimental contact spectrophotometric method, with Spectral Reflectance Factor (SRF), was used
for colorimetric characterization, using a portable Konica-Minolta CM2600D instrument equipped with
an integrating sphere in the geometry d/8°, that produces a mathematical calculation of the tristimulus
values, choice the measurement geometry, the type of illuminant and the standard observer amongst
those regulated by the Commission Internationale de l’éclairage (CIE). Preliminary results on mortar
characterization showed two different colorimetric groups, both structural and mineralogical.
References [1] O. Gómez-Laserna, N. Prieto-Taboada, I. Ibarrondo, I. Martínez-Arkarazo, M. A. Olazabal, J. M. Madariaga,
Brick and Mortar Research, 2012, pp. 195–214.
[2] S. Martinez-Ramirez, S. Sanchez-Cortes, J. V. Garcia-Ramos, C. Domingo, C. Fortes, M. T. Blanco-Varela,
Cement and Conrete Research, 2003, 33, 2063–2068.
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Roman ceramics from Vicofertile (Parma, Italy): micro-Raman
study of the heat diffusion during the production process
Elisa Adorni,1* Danilo Bersani,2 Pier Paolo Lottici,2 Talisa Cerasoli,2 Lorenzo
Sambo,1 Irene Aliatis,2 Manuela Catarsi3
University of Parma, Department of Civil- Environmental Engineering and Architecture, Parma,
Italy, +39 0521 905961, [email protected], [email protected]
2
University of Parma, Department of Physics and Earth Sciences, Parma, Italy, +39 0521 905239,
[email protected], [email protected], [email protected]
3
Soprintendenza per i Beni Archeologici dell’Emilia-Romagna, Museo Archeologico Nazionale di
Parma, Parma, Italy
1
The present work focuses on the archaeometric characterization of Roman ceramics from Vicofertile
(Parma, north-west Italy), with the main aim of defining the production systems, the surface finishing
and the origin of the clays and to identify the production areas, through a multi-methodological
approach.
In 2008, during the two-year campaign of excavations in the area of Vicofertile, five Roman villas of the
end of the first century AD, modified till the Imperial age with the addition of wineries and furnaces,
were discovered.
From the villas, twenty-eight samples of Roman ceramics were selected: amphorae with seals, terra
sigillata pottery with in plantapedis seals, fragments of thin-walled ceramics, black painted pottery
and an antefix.
The samples were mineralogically and petrographically analyzed to characterize the composition of
temper, ceramic body and decorations.
The use of micro-Raman spectroscopy, in particular for the identification and understanding the
structural changes during a fire treatment, is well established.[1–5]
In this article, in addition to the standard characterization of the components of ceramic body and
surface, Raman mapping was extensively carried out along the thickness of the ceramic samples to
define the heat distribution during the production process. The collected data were compared with the
peculiar shape of the ceramics and the ancient types of kilns to compare the real distribution of heat
and its effect on the ceramic artifacts.
Figure 1. Raman maps obtained from the main bands of feldspar,
hematite and quartz on a cross section of a red Roman ceramic; brighter
shade means larger peak intensity.
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References
[1] P. Colomban, N. QuangLiem, G. Sagon, H. XuanTinh, T. Ba Hoành. J. of Cultural Heritage. 2003, 4, 187–
197.
[2] P. Colomban, Applied Physics A. 2004, 79, 167–170.
[3] D. Bersani, P. P. Lottici, S. Virgenti, A. Sodo, G. Malvestuto, A. Botti, E. Salvioli-Mariani, M. Tribaudino, F.
Ospitali, M. Catarsi, J. of Raman Spectrosc. 2012, 41, 1266–1271.
[4] Š. Pešková, V. Machovič, P. Procházka, Ceramics – Silikáty. 2011, 55, 410–417.
[5] M. C. Zuluaga, A. Alonso-Olazabal, M. Olivares, L. Ortega, X. Murelaga, J. J. Bienes, A. Sarmiento, N.
Etxebarria, J. of Raman Spectrosc. 2012, 43, 1811–1816.
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Raman spectroscopic study on ancient glass beads found in
Thailand archaeological sites
Krit Won-in,1 Yatima Thongkam,2 Pisutti Dararutana3*
Faculty of Science, Kasetsart University, Bangkok, Thailand
Faculty of Archaeology, Silpakorn University, Bangkok, Thailand
3
The Royal Thai Army Chemical School at the Royal Thai Army Chemical Department, Bangkok,
Thailand
1
2
Various colors of glass beads excavated at different archaeological sites in Thailand such as Khlong
Thom, Phu Khao Thong, Nang Yon, Thung Thuk, Khao Sri Vichai, Khao Sam Kaeo, Laem Pho, HorEk, U-Thong and Huay Yai Tai were characterized non-destructively using Raman spectroscopy and
X-ray fluorescence spectroscopy in order to determine the glass composition and the glass production
technology in ancient time. The Raman spectra and XRF analysis classified that they were mostly alkalibased glass matrix. Some were lead-based glass. Their compositions were similar to Mediterranean,
Islamic and Indian glasses, but higher concentration of aluminum. The colors were affected from
the transition metal ions’ addition, such as copper, iron and manganese. Tin and lead were mostly
presence in the opaque color samples. Consideration of the glass compositions and colorants, it could
be assumed that there was some technological production which related with South-East Asia, South
Asia, East Asia and Asia Minor. The information led to gain knowledge of the historic link of the long
distance trade and exchange networks in the ancient maritime.
Acknowledgements
This work was partly funded by the Faculty of Science at Kasetsart University. Authors were kindly
thanks Captain Boonyarit Chansuwan from the 15th Regional Office of Fine Arts at Phuket Province
for supporting the glass bead samples. The Maejo University at Chiang Mai and the Plasma and Beam
Physics Research Facility at Chiang Mai University and the Gem and Jewelry Institute of Thailand
(Public Organization) at Bangkok were also thanked for providing SEM-EDS, PIXE and Raman
spectroscopy, respectively.
References
[1] H. Veeraprsert, Khlong Thom: An ancient bead-manufacturing location and an ancient entrepot. Early
Metallurgy, Trade and Urban Centres in Thailand and Southeast Asia, White Lotus: Bangkok, 1992.
187
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Identification of Neolithic jade found in Switzerland studied using
Raman spectroscopy: Jadeite- vs. Omphacite- jade
Alessia Coccato,1 Stefanos Karampelas,2* Marie Wörle,3
Samuel van Willingen,4 Pierre Pétrequin5
Ghent University, Department of Archaeology, Ghent, Belgium, [email protected]
Gubelin Gem Lab, Lucerne, Switzerland, [email protected]
3
Suisse National Museum, Collection Centre, Affoltern am Albis, Switzerland
4
Suisse National Museum, Archeological Department, Zurich, Switzerland
5
Grande Rue 71, 70100 Gray, France
1
2
Objects made of jade, principally tools because of toughness of the rock, were used by humans since
VI-IV millennia b.C. and are today found in excavations throughout the world (from Europe to far East
as well as to Central and South America). In the course of time, jade became also a greatly appreciated
gem (mainly to Far East). The term jade could signify different material. For example, for gemologists
the term jade refer to virtually (>90%) amphibolitic and pyroxentitic monomineralic rocks; e.g.,
nephrite- and jadeite- jade respectively.[1] For archeologists, the term jade includes much more rocks,
not forcibly monomineralic. Neolithic artifacts (e.g., axe-heads) made of “jade” were found all over the
Europe.[2-5] Some Neolithic jade artifacts were also found in different places in Switzerland as well. The
present study is focused to the identification by Raman spectroscopy of the sodic or sodic-calcic mono
mineralic pyroxenites; i.e., the jadeite- and omphacite- jade.
Twelve finished and semi-finished green stone objects coming from excavations carried out in
Figure 1. Ramanspectra with green laser of two rough samples
collected recently. The bottom spectrum is of a jadeite-jade (main
band at around 700 cm-1and a double band at around 1000 cm-1) and
the upper spectrum is of anomphacite (main band at around 680 cm-1
and a double band at around 1020 cm-1).
Switzerland were selected among the collection of the Swiss National Museum (SNM) of Zurich,
covering a wide range of materials and shapes. Some rough samples were recently collected (by one of
the authors -PP-) from North Italy (Piedmont), where the jade was sourced during Neolithic. In Table
1 are reported some of the studied samples, their provenance, dimensions and description.
Micro-Raman spectroscopy is useful for the characterization of jade (see some examples to [6,7]
Raman spectra were acquired at the Gübelin Gem Lab (GGL) in Lucerne with a Renishaw Raman
1000 spectrometer coupled with a Leica DMLM optical microscope. All spectra were recorded using
an excitation wavelength of 514 nm emitted by an argon ion laser (Ar+) and most were taken using
standard mode (with 50x magnification). Raman spectra were acquired from 200 to 4000 cm−1 using
a power of 5 mW on the sample, with an acquisition time of 60 seconds (3 cycles) and about 1.5 cm−1
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resolution. Rayleigh scattering was blocked by a holographic notch filter, the backscattered light was
dispersed on an 1800 grooves/mm holographic grating and the slit was set at 50 μm. More than one
measurements were acquired to the most of samples and most of them were also measured with other
means such us EDXRF and micro-FTIR (results not presented here).
Raman spectra of omphacite-jade and jadeite-jade are slightly different, jadeite shows a main band at
around 700 cm-1, as well as two weak bands around 1000 cm-1 and a group of peaks below 400 cm-1.
[8,9]
On the other hand, omphacite spectra present an intense band at around 680 cm-1, a broad band
at around 1020 cm-1 and a group of peaks between 300 and 450 cm-1.[9,10] These differences are due to
slight differences to their chemistry and structure.[11] Raman spectra of the rough reference samples
recently collected in situ from the Northern Italy are presented in Figure 1. The studied archeological
samples, which are similar macroscopically as well as under microscope, are not only jadeite-jade but
also omphacite-jade. These results were cross-checked with other means (FTIR and/or EDXRF).
Nowadays, jadeite-jade and omphacite-jade is not only found in Italy but also in Russia, Burma, Japan
and Greece.[1]However, no remains of Neolithic minning or references to it, has yet been found.
References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
G. E. Harlow, S. S. Sorensen, V. B. Sisson, Short Course Handbook Series. Ed. L. A. Groat, 2007, 207–254.
P. Petrequin, S. Cassen, C. Croutsch, O. Weller, Notae Praehistoricae. 1997, 17, 135–150.
P. Petrequin, M. Errera, A. M. Petrequin, European Journal of Archaeology. 2006, 9(1), 7–30.
C. D’Amico, R. Campana, G. Felice, M. Ghedini, European Journal of Mineralogy. 1995, 7(1), 29–41.
C. D’Amico, Archaeometry. 2005, 47(2), 232–252.
A. G. Badou, D. C. Smith, F. Gendron, J. of Archaelogical Science. 2002, 29 (8), 837–851.
D. C. Smith, Geomaterials in Cultural Heritage. Ed. M. Maggetti & B. Mesigga, 2006, 10–32.
H. Shurvell, L. Rintoul, P. M. Fredericks, The Internet Journal of Vibrational Spectroscopy. 2004, 5,
http://www.ijvs.com/volume5/edition5/section2.html.
[9] rruff.info
[10]A. Katerinopoulou, M. Musso, G. Amthauer, Vibrational Spectroscopy. 2008, 48(2), 163–167.
[11]P. Makreski, G. Jovanovski, A. Gajović, T. Biljan, D. Angelovski, R. Jaćimović, Journal of Molecular Structure.
2006, 788(1–3), 102–114.
189
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P59
Raman Spectroscopy as useful tool for the gemmological
certification and provenance determination of sapphires
Barone Germana,1* Bersani Danilo,2 Crupi Vincenza,3 Longo Francesca,3
Ugo Longobardo,4 Majolino Domenico,3 Mazzoleni Paolo,1 Simona Raneri,1
Venuti Valentina3
University of Catania, Department of Biological, Geological and Environmental Sciences, Catania,
Italy, [email protected]
2
University of Parma, Physics and Earth Science Department, Parma
3
University of Messina, Department of Physics and Earth Sciences, Messina, Italy
4
Jeweller – Catania, Italy
1
In the last decade Raman spectroscopy was used for routine investigation in the characterization of
gems,[1] as it offers many advantages for gemological purposes being nondestructive and noninvasive
and granting short measurement times, low amount of material and no sample preparation.
In this context, this work is focused on the spectroscopic characterization of different kinds of
sapphires, by using handheld Raman instrumentation, in order to
furnish gemological certification and to acquire information about the
provenance of the gems.
In particular, the aim of the present study is to distinguish between
natural and synthetic sapphire and identify imitations gems. The
Raman spectra are collected by means of a portable MiniRam™ series
spectrometer (MADAtec) using a wavelength of 785 nm as excitation
source, in the spectral range 175 – 3150cm-1.
In order to perform further and deeper analysis on some selected
samples, in particular for the characterization of the inclusions, a
confocal JobinYvon Horiba Labram, equipped with the 632.8 nm and
Figure 1. Raman spectra of
473.1 nm excitation lines, is used.
The obtained data could improve the existing databases of gem spectra sapphire sample.
recently built and wide available also in the Web.[2–5]
References [1] D. Bersani, P. P. Lottici, Anal. Bioanal. Chem. 2010, 397, 2631–2646.
[2] RRUFF Project (2010) Department of Geosciences, University of Arizona, Tucson, USA. http://rruff.info/.
Accessed 01 Mar 2013.
[3] Minerals Raman Database (2010) Physics Department, University of Parma, Italy. http://www.fis.unipr.it/
phevix/ramandb.php. Accessed 01 Mar 2013.
[4] Handbook of Minerals Raman Spectra (2010) Ecole normale supérieure de Lyon, Lyon. http://www.enslyon.fr/LST/Raman/index.php. Accessed 01 Mar 2013.
[5] Raman spectra database, Dipartimento di Scienze della Terra, Università di Siena (2010). http://www.dst.
unisi.it/geofluids/raman/spectrum_frame.htm. Accessed01 Mar 2013.
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Authentication of ivory by means of 1064 nm Raman spectroscopy
and X-ray fluorescence spectrometry
Maurizio Aceto,1* Alessandro Crivelli,2 Pietro Baraldi,3 Maurizio Bruni,2 Angelo
Agostino,4 Gaia Fenoglio4
1
Dipartimento di Scienze e Innovazione Tecnologica (DISIT), Università degli Studi del Piemonte Orientale,
Alessandria, Italy; Centro Interdisciplinare per lo Studio e la Conservazione dei Beni Culturali (CenISCo),
Università degli Studi del Piemonte Orientale, Italy, +39 0131 360265, [email protected]
2
Nordtest s.r.l., Serravalle Scrivia (AL), Italy
3
Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, Modena,
Italy
4
Dipartimento di Chimica, Università degli Studi di Torino, Torino, Italy; Nanostructured Interfaces and
Surfaces Center of Excellence (NIS), Torino, Italy
Authentication of ivory has long been a problematic issue for archaeometry, as long as non-invasive
analysis was concerned. It is hard to discriminate among ancient and modern ivory without using
invasive and destructive measurements such as elemental content determination (carbon, nitrogen or
fluorine content) or isotope ratio analysis. At the same time, ivories obtained from different animal
species (elephant, hippopotamus, marine animals, etc.) can hardly be differentiated, since the
composition keeps fairly constant among themselves. An analytical protocol for identification of the
origin of ivories was proposed by Edwards et al. in several studies [1,2] in which the authors used FTRaman spectroscopy. In the spectra obtained from ivory samples, the typical spectral features of both
inorganic components, i.e. hydroxyapatite, and organic components, i.e. collagen, were identified and
used by means of chemometric procedures in order to recognise the different species from which teeth
and tusks ivory was produced. In a similar way, authors tried to individuate some spectral features
useful to distinguish among modern and ancient ivory [3] but it was found that these features were
highly dependent on the conservation history of the samples. An alternative approach was proposed
with FT-IR spectrophotometry, still combined with chemometric procedures [4].
A major drawback of these procedures is that they were entirely based on measurements performed in
laboratory. Most precious ivory artworks, however, cannot be moved from museums, due to their value
and fragility, especially in cases where ancient items are concerned. In these cases portable instruments
are needed, which should guarantee similar performances in the production of analytical information.
In this study a combined Raman spectroscopy – X-ray fluorescence spectrometry is proposed to allow
discrimination among ancient and modern ivory samples and among different animal species. Both
techniques were used in portable version, in order to perform analyses in situ without need of moving
samples. Raman spectroscopy was performed with the innovative Rigaku XantusTM-1064 spectrometer,
equipped with 1064 nm laser source which showed to be the most suitable for analysis of ivories.
Acknowledgements
This work has been financially supported by Nordtest s.r.l.
References
[1] H. G. M. Edwards, D. W. Farwell, Spectrochim. Acta A. 1995, 51, 2073.
[2] R. H. Brody, H. G. M. Edwards, A. M. Pollard, Anal. Chim. Acta. 2001, 427, 223.
[3] D. A. Long, H. G. M. Edwards, D. W. Farwell, J. Raman Spectrosc. 2008, 39, 322.
[4] C. Paris, S. Lecomte, C. Coupry, Spectrochim. Acta A. 2005, 62, 532.
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Characterization of emeralds by micro-Raman spectroscopy
Danilo Bersani,1* Pier Paolo Lottici,1 Emma Salvioli-Mariani,1 Erica
Lambruschi,1 Alessandro Francioli,1 Giulia Azzi,1 Germana Barone,2
Paolo Mazzoleni,2 Ugo Longobardo2
Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Parma, Parma, Italy,
2
Dipartimento di Scienze Biologiche, Geologiche ed Ambientali, Università degli Studi di Catania,
Catania, Italy
1
In recent years the use of Raman spectroscopy as a gemological tool has largely increased. In
particular, in the conservation science field, the possibility to have a quick, non-destructive, contactless
identification of a gem, maybe mounted on precious archaeological item, made this technique an
invaluable procedure for gemologists and conservators.
The results of the Raman analysis are not limited to the simple identification of a gem. In this work we
show the large amount of information which is possible to obtain on one of the most important gems,
emerald, the green variety of beryl.
We studied by means of a standard micro-Raman spectrometer a large group of emeralds in different
forms and of different origin: 15 faceted gems and a series of raw crystals (some of them still embedded
in the host rock) coming from Val Vigezzo (Western Alps). Some fakes have been identified between
the faceted gems (a garnet, a glass, a “quartz-beryl” sandwich). All the natural gems and crystals have
been fully characterized from the vibrational point of view. In particular, the high frequency spectrum,
in the OH-rich region, was used to estimate the amount of alkali ions present in the channels of the
structure.[1] To quantify Be and Li, alkali ions in the channels such as Cs, Rb, K, Na, and other elements
which better define the structure of beryl such as V, Cr, Mn, Fe analyses with LA-ICP-MS have been
performed.
Figure 1. Raman spectra of two simulants found
Figure 2. Raman spectra of an emerald coming from Val Vigezzo and of
between the faceted gems and the characteristic Cr3+
the liquid and gas phases present in a fluid inclusion; the broad band of
luminescence of the emerald excited at 473.1 nm.
liquid water, the sharpest one of the channel water at ~3600 cm-1 and the
peak of methane at 2915 cm-1 are clearly visible.
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In addition, solid inclusion were identified and used as a tool to differentiate the provenance of the
emeralds. The shape and the position of the characteristic laser-induced luminescence of chromium
ions was used to better define the origin of the gems.[2]
Fluid inclusions present in the alpine crystals were studied; the identification of the phases and their
concentration obtained by micro-Raman spectroscopy was completed by thermal analysis in order to
made hypothesis on their genesis.
References
[1] M. Łodziński, M. Sitarz, K. Stec., M. Kozanecki, Z. Fojud, S. Jurga. J. of Molecular Structure. 2005, 744–
747: 1005–1015.
[2] I. Moroz, M. Roth, M. Boudeulle, G. J. Panczer. Raman Spectrosc. 2000, 31, 485.
193
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Raman micro spectroscopy of inclusions in gemstones
from a chalice made in 1732
Miha Jeršek,1* Sabina Kramar2
1
2
Slovenian Museum of Natural History, Ljubljana, Slovenia, [email protected]
Slovenian National Building and Civil Engineering Institute, Ljubljana, Slovenia
Sacral heritage of Slovenia is well documented and described.[1]Of special interest among the various
chalices, monstrances and other vessels are the arte facts decorated with gems. The most outstanding
in this respect is no doubt the baroque chalice made in 1732 with no less than 459 embedded
gemstones.[2]
The chalice, made of wrought and cast silver with engraved and chased decoration, and fully goldplated,
is 30.2 cm high and measures 11.2 cm in diameter at the rim (Figure 1). It was manufactured in Graz,
which in those times, during the Baroque period, was an important goldsmith'sandart centre. No data
as to the chalice's manufacturer are at hand, except for the initials I. H. engraved and preserved in the
chalice. In the interior of the chalice's foot, a plate with engraved inscription is attached, which reveals
that this artefact, decorated with most precious gems, was commissioned by Sigismund Feliks, the
Bishopof Ljubljana.[1]
In 2001, all 459 gemstones on the baroque chalice were accurately inventoried, with their dimensions
measuredand the as well as colour and type of gems determined.[1] On the basis of macroscopic
observations, examination with a 10 x magnifying glasses, the conductivity and macroscopic analysis
of the inclusions in the gems, the researchers determined 68 amethysts, 101 garnets, 93 rubies, 4
sapphires, 152 emeralds, 15 citrines, 24 diamond sand one sample of glass and dyed agate each.
The jewels in the baroque chalice include numerous inclusions, some of which are recognisable already
through a 10x magnifying glass, such as colourzoning in sapphires. With the aid of gemological
microscope or stereo lens, other more or less characteristic inclusions can be detected as well, such
as rutile needles, which give the distinctive appearance of silk, stress cracks around the zircon, liquid
inclusions in the form of fingerprint, etc.
Some solid inclusions, however, bear such a strong resemblance with each other that they simply can not
be determined merely on the basis of observations of their morphology, orientation and size. This is the
reason why we examined the gems embedded in the baroque chalice with Raman micro spectroscopy
that enabled us to identiy the numerous solid inclusions in the majority of the stones, particularly in
emeralds, garnets, rubies and sapphires.
Identification of solid inclusions helps us not only to determine the types of gemstones, but primarily
Figure 1.Baroque chalice with 459 gemstones (left) with some detail (right).
Photo: Ciril Mlinar
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to detect the sites and origin of gemstones.[3]In 1732, when the chalice was made, not all gemstone sites
were known as yet. Diamonds were known to originate from India and Brazil, emeralds from Egypt,
Habachtal in Austria, from the region of modern-day Afghanistan, Columbia and the Ural Mts. In
those times, rubies were duglargely in SriLanka and Burma (present-day Myanmar), garnets in the
Czech Republic, India and Africa, amethysts and citrines in some additional places as well.
Through the analysis of solid inclusions by Raman microspectroscopy we managed to identify the types
of solid inclusions in the jewels from the baroque chalice and thus to additionally confirm their origin
in this most noble sacral vessel kept in Slovenia.
References
[1] M. Simoniti, Zakladi slovenskih cerkva. Narodna galerija: Ljubljana, 1999, p. 199.
[2] M. Jeršek, F. Šerbelj, B. Mirtič, Dragulji in motivi v kelihu iz leta 1732. Scopolia, 2001, 47, 42.
[3] J. E. Gübelin, I. J. Koivula, Photoatlas of Inclusions in Gemstones, 3rd edition, Drückerei Wintherturdw
AG: Zürich, 1997, p. 532.
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Spectroscopic investigation: impurities in azurite as provenance
markers
Mariafrancesca Aru,1 Lucia Burgio,2* Mike Rumsey3
Physics Department, University of Parma, Parma, Italy, [email protected]
Victoria and Albert Museum, London, UK, +44(0)2079422114, [email protected]
3
Department of Earth Sciences, Natural History Museum, London, UK, +44(0)2079426034,
[email protected]
1
2
Background and objectives. As pigment microscopists know by experience, when one or more
layers of azurite (a basic copper carbonate frequently used as a blue pigment in the past) are seen in
a cross section, the blue particles are often intermixed with small amounts of impurities. Normally
these are not related to other artists’ materials present nearby in the object, although occasional
contamination should never be ruled out; the impurities present in the azurite-containing layers are
typically green or orange-brown, although other colours can also be seen, and usually correspond to
particles of malachite and iron oxides such as hematite and goethite,[1,2] which have traditionally been
used as artists’ pigments in their own right since antiquity. This observation triggered a study aimed
at finding out if those impurities were deliberate additions by the artist, or if they were present in the
original mineral material. This study involved in the first instance the identification of the impurities
(if any) present in high quality mineral specimens of azurite, i.e. specimens, which could have been
chosen as a raw material for making the blue pigment in medieval and Renaissance time. Are different
mines associated with specific impurities? Can these impurities, once they are found in azurite-based
paint layers on museum objects, help identifying what mine the original source of azurite came from
and therefore help reconstructing trade routes and mine usage over time? To find out, a collaborative
pilot study was conducted between the Victoria and Albert Museum and the Natural History Museum,
London. The latter provided 19 specimens of azurite from their historical collections, the provenance of
which matched the azurite mines known in medieval Europe (Hungary, Germany, Austria, Spain etc.).
Method. The specimens were analysed by Raman microscopy in the first instance; this technique was
chosen because it allows analysing minute impurities with minimal interference from surrounding
materials. When possible, for each specimen both the matrix (i.e. the part of the host rock that the azurite
crystals formed on, usually containing a high concentration of impurities) and apparently homogenous
crystals or crystalline areas of azurite were analysed as they were, (i.e. as unbroken portions of mineral
not yet reduced to powder). The crystalline azurite samples were subsequently ground to achieve a
high-grade pigment powder, with grain size ranging from 1 to 15 _m. The powder thus obtained was
then analysed in detail by Raman microscopy and a record was kept of all materials present as well as
of any identification achieved. X-ray fluorescence and SEM-EDX analyses were occasionally carried out
to support the Raman results.
Results. The study was undertaken with full awareness of its limitations at this stage: it is not
statistically significant yet due to the relatively small number of specimens analysed; it is being assumed
in first approximation that one or two samples can be taken as representative of a whole mine; the oldest
specimens are likely to be from the end of the 18th century, therefore a lot ‘younger’ than any specimens
mined in medieval times. The results obtained were therefore considered as preliminary, and further,
more in-depth surveys will be conducted in the future. Nonetheless, several facts were ascertained:
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1) Goethite and hematite were found in almost every specimen analysed (13 and 14 out of 19, respectively),
and malachite was detected in more than half of them; this is unsurprising as these minerals form
and are stable under the same general conditions in nature that produce azurite. This confirmed that
the presence of the three dominant material impurities in azurite-containing pigment layers can be
ascribed to nature rather than artistic choice.
2) The red copper oxide cuprite, where present, is likely to be a remnant of the original copper-containing
material(s) that actually lead to the production of the azurite from weathering/oxidation;
3) Calcite, quartz and two polymorphs of titanium dioxide, anatase and rutile, were also found fairly
regularly. These minerals are examples of what geologists would term rock forming minerals and it
would not be uncommon to find these specific minerals within the matrix of the specimens studied. As
such it is hard to use these as markers for specific mines, although other rarer rock forming minerals or
their relative proportions to each other in an azurite specimen may prove more distinctive.
4) Impurities such as jarosite, cerussite and rhodochrosite occur in a smaller number of specimens, but
do not seem to be unique to one location alone.
5) The presence of cinnabar in all three Austrian specimens analysed is puzzling and needs to be
investigated further to figure out if HgS is a possible marker (as there are mercury mines in the area) or
represents a historical environmental contamination, possibly from before the specimens entered the
NHM collections (as contamination within the V&A was ruled out).
Conclusion. The results of this pilot/preliminary study confirmed that the presence of abundant
particles of pigment-type materials (such as malachite, hematite and goethite) within paint layers
made of azurite is not due to a deliberate choice by the artist but is rather the consequence of the way
azurite forms in nature and the minerals it is often associated with. Other materials, such as cuprite,
calcite, quartz, anatase and rutile, which can occasionally be found as rare impurities in art objects
painted with azurite, were found fairly regularly in the mineral specimens of azurite, and cannot be
used as markers for provenance due to their ubiquity. Finally, further studies will be needed to find
out if the materials that were identified less frequently (such as jarosite or cerussite), as well as their
relative proportion, can help to narrow down the provenance of the original azurite mineral. A larger,
more statistically significant sample set will be required to reach further conclusions relating azurite
provenance to mineralogical impurity.
Acknowledgements
The authors gratefully acknowledge the assistance of Prof. Danilo Bersani, University of Parma, in the
interpretation of some of the Raman spectra collected during this study.
References
[1] L. Burgio, R. J. H. Clark, R. R. Hark, PNAS. 2010, 107, 5726–5731.
[2] L. Burgio, A. Cesaratto, A. Derbyshire, J. of Raman Spectrosc. 2012, 43, 1713–1721.
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Implementation of scientific methods of fine art authentication
into forensics procedures: the case study of “Bolko II Świdnicki”
by J.J Knechtel
Barbara Łydżba-Kopczyńska,1 Marcin Ciba,2 Grzegorz Rusek1
University of Wroclaw, Faculty of Chemistry, Cultural Heritage Research Laboratory, Wroclaw,
Poland, +48 71 3757379, [email protected]
2
Institute of Art History, Faculty of History, Jagiellonian University, Kraków, +48 12 663 1848
1
Over the last few years the Fine Art Market generated more than billion of dollars just in US, but there
are suggestions that many pieces of arts that are being sold are of questionable authenticity. The number
of fakes, forgeries and copies that appear on the art market in Poland in recent years is significantly
growing, whereas the selection and standardization of procedures of verifying the authenticity of
objects of art is not up to date, and seems to be losing the battle. Traditionally the decision is based on
the opinion of art expert or art historian. However, the real statement of authenticity should include at
least three levels of analysis: the confirmation of provenance, i.e. authenticity of documents supporting
ownership, the verification of the artistic style of work by art expert and scientific analysis of the object
using generally approved methods. The development of reliable document analysis was motivated
by requirements of business contracts, useful tools in verification of authenticity of investigated
masterpieces however, the subtle aspects of art style have been discussed by numerous experts over
the years and are still far from validation. Therefore the introduction of scientific methods of analysis
of object of art, based on examination of used materials and their transformations, may bring some.
The application of methodology used in forensic investigations, characterized by well defined
procedures of sampling, instrumental methods of analysis and data handling, leads to consistent and
reliable results, as could be seen in numerous cases of examinations of documents, drugs or explosives.
The scientific examination of piece of art incorporates the investigations of paintings materials
like pigments and media, canvas, wooden support, nails etc. with the application of wide variety of
noninvasive and non-destructive techniques. The discovery of the materials not consisting with the
supposed time of the creation would suggest that analyzed object is not authentic. On the other hand,
the consistency of all materials employed in the investigated piece of art with the time of creation does
not necessarily prove the attribution of that object. In this situation the question that the forensic
expert has to consider is how detailed the further analysis should be.
Our amassed experience gathered during recently accomplished authenticity and attribution
investigations of the paintings, documents and cartographic objects[1–3] suggests that the implementation
of forensic schemes into this type of investigations is beneficial. The schemes should cover the
procedures of collecting, storing and protecting samples, as well as validation of applied analytical
techniques. We consider the possibility of selecting the “authenticity/attribution markers” that would
help experts to evaluate the levels of authenticity similarly to fingerprints analysis.
Joseph Jeremias Knechtl, one of the most famous painters of XVIII century, was nearly completely
forgotten in following centuries. His artistic heritage is hardly known by art historians and his painting
techniques and materials employed by the artist have not been investigated. Recently in Lower Silesia
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in Poland several painting attributed to J.J. Knechtl were discovered in private collection. The problem
of authenticity of paintings preliminary attributed to J.J. Knechtl is attracting attention due to the
rising interest in Silesian art and the growing art market in Poland.
The painting “Bolko II Świdnicki” of questioned attribution was subjected to comprehensive
investigations based on noninvasive and nondestructive physicochemical analyses. Five paintings
characteristic for each period of the painter creativity were selected for comparatives study. UV and IR
photography was carried out to determine the state of the preservation of the paintings and to specify
area for collections micro-samples. Both, unprocessed paint samples and paint cross-section were
submitted to optical microscopy in order to characterize their stratigraphy. Application of ATR and
Raman spectrometry, SEM-EDX point analysis and mapping delivered information about employed
pigments and their distribution in different layers. HPLC analysis gave the complementary information
about employed organic media.
The results of the investigations allowed to verify the attribution of the painting “Bolko II Świdnicki”.
To test the hypothesis of attribution with reasonable significance the “authenticity/atribution markers”
were selected. The markers, their number and relations among markers chosen to test the hypothesis
will be disscussed.
References
[1] B. Łydżba-Kopczyńska, E. Kendix, S. Prati, G. Sciutto, R. Mazzeo, 5th International Congress on the
Application of Raman Spectroscopy in Art and Archaeology, Bilbao, Spain, 14–18 September, 2009, Book
of abstracts: Juan Manuel Madariaga (ed.), Bilbao: Universidad del Pais Vasco, Servicio Editorial, 2009, p.
87.
[2] M. Ciba, A. Kozieł, B. Łydżba-Kopczyńska, Obrazy Michaela Willmanna pod lupą, Muzeum Regionalne,
Jawor, 2010, pp. 1–111.
[3] B. Łydżba-Kopczyńska, L. Cartecchini, B. Doherty, Ch. Anselmi, D. Buti, Ch. Grazia, A. Romani, 2nd
International Congress of Chemistry for Cultural Heritage (ChemCH), Istanbul, Turkey, 8–11 July, 2012,
Turkish Chemical Society: Istanbul, 2012.
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Raman analysis of multilayer automotive paints in forensic science:
measurement variability and depth profile
Danny Lambert,1* Cyril Muehlethaler,1 Line Gueissaz,1 Geneviève Massonnet1
1
School of Criminal Justice, University of Lausanne, UNIL-Sorge Batochime, Lausanne-Dorigny,
Switzerland, +41 (0)21 692 46 28, [email protected]
Paint analysis in forensic sciences is involved in diverse areas as the expertise of automotive paint),
graffiti [1] household [2] or more generally, in the comparison of a trace evidence with a reference sample.
[3]
The criminalist’s objectives are both to identify the main components of a paint system and compare
the composition of a trace and a reference sample, in order to infer on a potential common source.
This follows a two-steps process: first a comparison based on the analytical results of the trace and
reference sample is performed. This is then followed by an evaluative step to give information on the
strength of the link potentially highlighted during the comparison process. Therefore several paints are
examined. From the trace collection on a crime scene to the laboratory analysis, the paint samples will
undergo various examinations, demanding different sample preparations.
Comparison and identification of paint samples are achieved by different techniques, including
microscopy, micro-spectrophotometry (MSP), elemental analysis (X-ray fluorescence (XRF) or scanning
electron microscopy – energy dispersive X ray analysis (SEM-EDX)), Fourier-transform infrared
spectroscopy (FTIR), Raman spectroscopy and pyrolysis gas chromatography mass spectrometry
(pyGCMS).
Raman spectroscopy is appreciable as it requires few or no special sample preparation.[4,5] A recent
study [6] demonstrates that Raman spectroscopy suffers from reproducibility problems which could be
problematic in statistical treatments application (chemometrics). Actually, when attempting to develop
chemometric treatments to classify and compare Raman spectra, it is imperative to minimize the
variability among replicates of the same sample (defined as intra-variability). Therefore, the parameters
that influence the distributions of the intra- and inter-variability (variations between measures from
different reference samples) must be optimized. The ideal situation would be when the two distributions
don’t overlap and when the intra- is a narrow distribution, in contrary of inter- which must be as
broad as possible.[7] To reach this goal, the factors having an influence on the intra-variability must be
identified in order to minimize them.
When a multilayer paint sample is analysed, two types of analysis procedures are frequently encountered:
cross-section of the sample (realized with a microtome) for the analysis of the layers and the so-called
in situ analysis, which is realized without sample preparation. These two analysis procedures were
evaluated in this research.
In order to evaluate their influence as well as other analytical parameters on the intra-variability, a
design of experiment (DoE) such as “fractional full factorial” was used. The following parameters were
also considered: the paint type, laser spot size, objective magnification, microscopic slide type, number
of accumulations and exposure time of the CCD. This statistical approach has the advantage of reducing
the number of necessary experiments while allowing the visualization and the understanding of the
impact of the tested factors on the measured response (in this research the variability).[8] The data
collected were then analysed with chemometric tools such as principal component analysis (PCA) to
observe the data distribution. The main outcome shows that analysis procedure has a more important
effect than other tested parameters.
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To explore this result, surface characteristic (smooth or rough surface) of the sample were investigated.
For multilayer samples with a clearcoat, its influence was also assessed through depth profile
measurements. It was noted that the coloured layer can be measured through the clearcoat in order to
avoid a preparation step. The findings of this study demonstrate the influence of sample preparation,
on the variability of the measurement. All the conducted experiments show that the measurement
variability on the colour layer is greater with a cross-section of the sample than in situ, even when
analysing through a transparent medium (clearcoat). Thus, it is preferable to conduct in situ analysis
of an automotive paint sample, when it is possible, rather than its cross-section to provide less
measurement variability in the context of using a database.
This survey helps to provide measuring guidelines to other laboratories in order to get the more
reproducible spectra as possible. This study is part of a more general research on the comparability of
Raman analyses between forensic laboratories.
References
[1.] J. De Gelder, P. Vandenabeele, F. Govaert, L. Moens, J. of Raman Spectrosc. 2005, 36(11), 1059–1067.
[2.] P. Buzzini, G. Massonnet, Science and Justice – J. of the Forensic Science Society. 2004, 44(3), 123–131.
[3.] S. E. J. Bell, L. A. Fido, S. J. Speersand, W. J. Armstrong, Applied Spectroscopy. 2005, 59(1), 100–108.
[4.] P. Buzzini, G. Massonnet, F. M. Sermier, J. of Raman Spectrosc. 2006, 37(9), 922–931.
[5.] G. Ellis, M. Claybourn, S. E. Richards, Spectrochimica Acta Part A. 1990, 46(2), 227–241.
[6.] R. S. Das, Y. K. Agrawal, Vibrational Spectroscopy. 2011, 57(2), 163–176.
[7.] C. Muehlethaler, G. Massonnet, P. Esseiva. Forensic Science International. 2011, 209(1–3), 173–182.
[8.] P. Esseiva, L. Dujourdy, F. Anglada, F. Taroni, P. Margot. Forensic Science International. 2003, 132(2),
139–152.
[9.] D. R. Cox, N. Reid, The Theory of the Design of Experiments, Chapman and Hall/CRC, 2000.
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The Art of non-invasive in situ Raman spectroscopy:
identification of chromate pigments on Van Gogh paintings
Costanza Miliani1
1
Istituto CNR di Scienze e Tecnologie Molecolari (ISTM) and SMAArt, Dipartimento di Chimica,
Università degli Studi di Perugia, Perugia, Italy
Chrome yellows represent a class of pigments commonly used by painters of the late 19th-early 20th
century such as V. Van Gogh. It has been found that upon exposure to sunlight, the both the chemical
composition and the crystalline structure of the pigment critically influence the darkening behavior
of this class of materials. Synchrotron X-ray based investigations by means of micro X-ray absorption
near edge structure (µ-XANES), carried out on the artificially aged surface of a historic sulfate-rich
orthorhombic PbCr1-xSxO4 paint sample (Figure 1A) (Monico et al., 2011a) and on the sulfur-rich areas
of the brown layer of two paint microsamples from the Van Gogh paintings Bank of the Seine and Field
with flowers near Arles (both conserved at the Van Gogh Museum) (Monico et al., 2011b), allowed to
effectively ascribed this darkening phenomenon to the reduction of the original Cr(VI) to Cr(III). The
insights that chemical composition and the crystalline structure play a role in the alteration mechanism
of these pigments have been successfully demonstrated by studying photochemically aged oil paint
models made up of in-house synthesized lead chromate yellows (Monico et al., 2012a). Similarly to the
historical pigment, a profound darkening and the formation of up to about 60% of Cr(III)-species in
the outer layer was observed only for those paints composed of sulfate-rich PbCr1-xSxO4 (x≥0.4) and an
abundance of the orthorhombic phase higher than 30 wt % (Figure 1B).
Figure 1. Images of sulfate-orthorhombic rich PbCr1-xSxO4 (x~0.6-0.8)
paints of (A) historic and (B) in-house synthesized materials before and after
UVA-visible light exposure
If on the one hand investigations of model paint samples of either pure PbCrO4 or PbCr1-xSxO4
employing µ-XANES spectrometry made possible to attribute the alteration mechanism of the pigment
to a reduction reaction, on the other Raman [Monico et al., 2012b] allowed to characterize chrome
yellow pigments depending on their chemical composition (in terms of SO42-abundance) and crystalline
structure (Figure 2).
This preliminary spectroscopic study of paint model samples was very useful for the interpretation of
the data have been collected from several embedded micro-paint samples taken from several paintings
by V. van Gogh and contemporaries, on which both chrome yellow forms (either as pure PbCrO4 or
PbCr1-xSxO4) were detected.
Similarly, recent in situ non invasive MOLAB Raman investigations on the painting Sunflower
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(conserved at the Van Gogh Museum) allowed to map the distribution of pure chrome yellow in its coprecipitated forms, providing a possible explanation why only some chrome yellow-painted areas of the
painting are prone to darkening.
A detailed discussion of Raman spectra of chrome yellow pigments will be given and a comparison
between the results collected from model paint samples and those collected from paintings by V.van
Gogh and contemporaries will be illustrated highlighting potentialities and limitations of non invasive
Raman spectroscopy.
References
[1] L. Monico, G. Van der Snickt, K. Janssens, W. De Nolf, C. Miliani, J. Dik, M. Radepont, E. Hendriks,
M. Geldof, M. Cotte, Anal. Chem. 2011a, 83(4), 1214–1223.
[2] L. Monico, G. Van der Snickt, K. Janssens, W. De Nolf, C. Miliani, J. Dik, M. Radepont, E. Hendriks,
M. Geldof, M. Cotte, Anal. Chem. 2011b, 83(4), 1224–1231.
[3] L. Monico et al., Anal. Chem. 2012a: DOI: 10.1021/ac302158b.
[4] L. Monico et al., Anal. Chem. 2012b: DOI: 10.1021/ac3021592.
Figure 2. Raman spectra acquired by means of the bench-top (left) and portable (right)
instrumentation from oil paint model samples of both pure lead chromate (S1mono, S1ortho)
and solid solutions of PbCr1-xSxO4 (S3A-S3D).
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Characterisation of a new mobile Raman spectrometer for in-situ
analysis
Debbie Lauwers,1* Anna Garcia Hurtado,2 Vinka Tanevska,3 Luc Moens,1
Danillo Bersani,4 Peter Vandenabeele5
Department of Analytical Chemistry, Research Group Raman Spectroscopy, Ghent University, Ghent,
Belgium; +32 (0)9 264 47 19, [email protected], [email protected]
2
Universitat de Barcelona, Barcelona, Spain
3
Institute of Chemistry, Faculty of Natural Sciences and Mathematics, University ‘Ss.Cyril & Methodius’,
Skopje, Republic of Macedonia
4
Physics Department; University of Parma, Parma, Italy
5
Department of Archaeology, Archaeometry research group, Ghent University, Ghent, Belgium
1
Mobile Raman instrumentation is often used for in-situ characterisation and identification of inorganic and
organic materials in art and archaeometry.[1] In the literature, one can find several publications on on-site,
molecular examination of medieval wall paintings, museum objects, geo-biological samples, etc.[2–4] In all
these cases, the definition of mobile Raman spectroscopy is somewhat arbitrary: different authors have
different definitions. Colomban divides between mobile (instrument < 30 kg), ultramobile and hand-on
(instrument or probehead < 2 kg).[5] Smith on the other hand, used mobile instrumentation as general term
and made a distinction between portable (portable by 1 man) and transportable (transportable by 4 men)
instrumentation.[6]
In this work a new mobile instrument (cfr. defintion Colomban), EZRAMAN-I-DUAL Raman system
(Enwave Optonics, Irvine CA, USA) is presented. The fiber-optic-based device is equipped with two type of
lasers, a red diode laser (785 nm) and a green Nd:YAG laser (532 nm) and has three interchangeable lenses:
a standard lens (STD), a long working distance lens (LWD) and a high numerical aperture lens (HiNA). The
Raman spectrometer also consists of an adjustable power controller for each laser and has a CCD detector
as detection system. When comparing this Raman instrument to other spectrometers, several advantages
can be observed e.g. the possibility to use two lasers, to work on batteries, etc.
The aim of this project was to characterise this Raman system. This characterisation was twofold: (i)
Spectroscopic characterisation: develop a method for Raman shift calibration, check the stability of the
lasers and instrument (on short and long term), define the laser output power corresponding to different
reductions and the influence of grating change; (ii) Determination of characteristics needed for art
analysis (working distance, positioning equipment, determine the LOD of pigments). Finally, the Raman
spectrometer was also tested for its applicability for the in situ investigation of wall paintings.
The spectroscopic characterisation of the instrument consisted of several aspects. The examination of the
Raman shift calibration was performed with five reference products: sulphur, cyclohexane, 𝜀-caprolactone, acetonitrile/toluene (50:50) and polystyrene. The Raman bands of each standard (for both lasers and each
lens) were compared with the reference Raman wavenumbers, presented in the literature. [7] The correlation
indicated that a second calibration is necessary for lower wavenumbers, to obtain reliable results. Next to
the calibration, the stability of the instrument, on short and long term, was investigated by analysing the
fluctuation of the characteristic band position at 1001.4 cm-1 of polystyrene. The band positions over time
denoted to be significantly constant which affirms the instrument to be stable on short and long term. Using
the same method for the evaluation of the grating change (i.e. changing to the other laser), one can conclude
that the instrument must be calibrated when interchanging the excitation source.
Not only the stability of the instrument is an important feature, also the fluctuations of the laser wavelength
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must be examined. By comparing the results of the recorded neon emission lines with the lines presented
in the literature, it confirms both lasers to be stable with an average value of 784.9 nm and 531.8 nm for
the red and the green laser, respectively.[8] As final aspect, to complete the characterisation, the relationship
between the laser reduction and the corresponding laser output power at the sample was investigated. It
was been found that no spectra could be recorded with a laser output power at the source lower than 33%
for the 785 nm laser and 50% for the 532 nm.
The second part of the characterisation
contains the optimisation of the
methodology needed for art analysis. One
of the important factors for in situ Raman
investigations of precious artefacts, is the
working distance. By recording Raman
spectra of polystyrene and determining the
band intensity at 1001.4 cm-1, the optimal
acquisition distance could be defined. Apart
from the independency of the two laser
excitation sources, each type of lens has a
Figure 1. Preliminary result of the in situ set-up, developed in-house
different optimal working distance: 7-8mm
for the STD lens, < 1 for the LWD lens and
3mm for the HiNA lens. Next to the working distance, the positioning of the equipment is very important.
Figure 1 shows a preliminary result of the set-up, developed in-house.
After the characterisation of the new mobile Raman equipment, the efficacy of the instrument for pigment
analysis was tested, giving satisfactory results which evidence the suitability of the EZRAMAN-I-DUAL
instrument for pigment identification.
As a general conclusion one can say that, the EZRAMAN-I-DUAL Raman system, provides good
performance and spectra of good quality. The mobile spectrometer shows larger stability over short and
long term independent of the used excitation source. Apart from the two laser excitation sources, this
mobile instrument is equipped with three types of lenses (STD, LWD, HiNA) each with a different optimal
working distance: 7-8mm for the STD lens, < 1 for the LWD lens and 3mm for the
HiNA lens. Another important conclusion of this work is related to the laser power: it has been found that
no spectra can be recorder, lower than 33% of the laser output power at the source for the 785nm
laser and 50% for the 532nm.
Acknowledgements
This research is financially supported by the European Commission, through the FP-7 MEMORI
project ‘Measurement, Effect Assessment and Mitigation of Pollutant Impact on Movable Cultural
Assets. Innovative Research for Market Transfer' (http://www.memori-project.eu/memori.html).
References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
P. Vandenabeele, H. G. M. Edwards, L. Moens, Chem. Rev. 2007, 107, 675.
J. P. Vera, U. Boettger, R. Noetsel, F. Sanchez, D. Grunow, Planetary and Space Science. 2012, 74, 103–110.
M. Pérez-Alonso, K. Castro, J.M. Madariaga, Anal. Chim. A. 2006, 571, 121–128.
I. Reiche, S. Pages-Camagna, L. Lambacha, J. of Raman Spectrosc. 2004, 35, 719–725.
Ph. Colomban, J. Raman Spectrosc. 2012, 43, 1529–1535.
D. C. Smith, Spectrochim. Acta A. 2003, 59, 2353–2369.
M. R. McCreery, Raman spectroscopy for Chemical analysis, John Willey & Sons: New York, 2000.
H. Hamaguchi, Applied Spectroscopy reviews. 1988, 24, 137–174.
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On-site high-resolution Raman spectroscopy on minerals and
pigments
Martin A. Ziemann1*
1
Universität Potsdam, Institut für Erd- und Umweltwissenschaften, Potsdam, Germany,
+49 331 977-5876, [email protected]
Sample taking, touching or producing traces of analyses on valueable masterpieces and archeological
and art objects are increasingly considered undesirable or prohibited. Raman spectroscopy can meet
these demands, even if these objects cannot be transported to the lab and have to be studied on-site
with a mobile Raman system. Sometimes however, objects are big and/or located at considerable height
above the floor. Raman studies in the Grotto Hall of the New Palace, Park Sanssouci in Potsdam [1] we
started with a mobile Raman equipment, which allowed measurements to only up to 1.80 m height.
However, most of the 20.000 minerals, rocks and fossils in the Grotto Hall, that have to be identified
are in bands located up to 4 m high.
A new mobile Raman system was designed for on-site measurements in positions in up to 5 m high.
Thus, objects in any position in the Grotto Hall can be analysed, as well as pigments of wall paintings
in chapels, museums etc. The lateral resolution and stability of the system is in the range of 5 to 10 µm,
good enough for using a 50x ULWD micro-objective, thus allowing measurements on single pigment
grains or microscopic inclusions in minerals.
References
[1] M. A. Ziemann. J. of Raman Spectrosc. 2006, 37, 1019–1025.
207
Book of Abstracts
OP40
Molecular Characterization and Technical Study of Historic Aircraft
Windows and Head Gear Using Portable Raman Spectroscopy
Odile Madden,1,3* Kim Cullen Cobb,1 Alex M. Spencer1
1
2
Museum Conservation Institute, Smithsonian Institution, Suitland, MD, USA, [email protected]
National Air & Space Museum, Smithsonian Institution, Washington DC, USA
Introduction
Early aviation design incorporated the most innovative plastics available at the time, and examples
of these technologies are represented in the Smithsonian National Air and Space Museum (NASM)
collection. Particularly interesting, and unexplored until now, is the co-evolution of transparent sheet
plastics and the enclosure of cockpits in heavier-than-air aircraft of the 1920s and 1930s. A novel, noninvasive study of goggles, helmets, and airplane canopies in Smithsonian collections was undertaken.
It is the first known large-scale technical survey of aviation plastics and leverages the world’s largest
air and space collection as evidence of the materials and technologies used to create plastic objects in
the early-20th century. The study relied heavily on portable, adjustable focal length, fiber optic Raman
spectroscopy (AFL-FORS) and FT-Raman spectroscopy, techniques ideally suited to non-invasive
characterization of polymers and 3-dimensional plastic objects.
The Wright brothers’ first flew at Kitty Hawk in an open architecture aircraft. By 1910, pilots were
given some protection from the slipstream and elements by covering the aircraft’s skeletal frame with
fabric, leaving the top open for the pilot’s head and shoulders. These early cockpits were located behind
the engine, and the pilot was pelted with wind, rain, ice, oil, and the occasional bird that happened
into the propeller. All threatened the pilot’s ability to see and maneuver the plane. Goggles and small
windshields were a first defense, provided they did not fail.[1,2] As flying became more common,
ambitious pilots flew ever higher, faster, and year round,[3] which brought the need to enclose cockpits
and still see out of them.[4] This period coincided with the development of shatterproof laminated
safety glass and water-clear transparent plastic sheets that were lighter, more flexible, easier to shape,
and less likely to shatter on impact.[5,6] Aviation soon was a target market for these products.
Because the evolution of transparent window materials and plastic occurred on a similar trajectory,
early aircraft - the production history of which is well known - are an opportunity to study
developments in early transparent plastics. Written documentation of materials used tends to be from
plastic manufacturers’ research and development reports, marketing materials, and advertisements.
These offer valuable insight into what was available but may not coincide with what was used. The
Smithsonian Museum Conservation Institute (MCI) and NASM teamed up to evaluate the potential of
Raman spectroscopy to identify and characterize the plastics that actually were used.
Methods
Ninety aviator goggles, flight helmets, and aircraft windows were analyzed by Raman and XRF
spectroscopies. A portable BW Tek MiniRam II dispersive Raman spectrometer was the primary tool.
It incorporates a 785 nm excitation laser, fiber optic probe, and CCD detection with 10 cm-1 spectral
resolution. A custom adjustable focal length adapter was designed to facilitate analysis of laminated
glass structures. Fluorescent artifacts, particularly colored or deteriorated plastics, were analyzed by
Fourier-transform Raman spectroscopy using an enclosed, benchtop, research grade Thermo Scientific
NXR module attached to a 6500 Fourier transform infrared spectrometer. The Raman module features
1064 nm excitation using a YVO4 laser and electronically cooled InGaAs detection. Spectral resolution
was adjusted from 2-8 cm-1.
RAA 2013
208
OP40
Results and Conclusions
Portable Raman spectroscopy has proven a useful tool for identification of synthetic polymers,
plasticizers, and other compounds in plastic. It now is used routinely for sorting transparent and
colorless plastics at Smithsonian and often can identify major components of intentionally colored
or degraded plastics as well. We modified the portable spectrometer’s fiber optic probe to analyze
laminated glass structures, a category of materials not anticipated when the grant was written. The
addition of an adjustable focal length adapter allows us to focus the excitation laser on the polymer
within the laminated glass sandwich. We propose that adjustable focal length fiber optic Raman
spectroscopy (AFL-FORS) has great potential for analysis of transparent laminated structures, and
other situations where the material of interest is located within a transparent substance.
As expected, fluorescence interference was a challenge for many artifacts, particularly plastics that are
colored or contain polarizing media. Better spectra were obtained for many with a NIR FT-Raman
spectrometer, but the instrument is not portable and has a fixed sample compartment, which limits
the range of artifacts that can be analyzed. This finding underscores the value in developing portable
Raman spectrometers with NIR excitation.
Using these tools and X-ray fluorescence spectrometry we constructed a timeline for the development
of aviator eyewear and aircraft window materials through World War II. Open cockpit aircraft through
the 1920s incorporated small windshields of glass or laminated glass. Sheets of cellulose nitrate also
were used for windows where impact resistance and visibility were not vital. Pilots relied on goggles
for eye protection, and laminated glass lenses were common. Plasticized cellulose nitrate was the
laminating polymer from 1910 through the 1920s, when plasticized cellulose acetate began to supplant
it in safety glass and other applications. In 1939 polyvinyl butyral (PVB) was introduced as an ideal
safety glass laminating layer and still is used today. Transparent plastic sheets, particularly methyl
methacrylate, were developed in around 1937 for windows and canopies and quickly were incorporated
in American and German aircraft during World War II.
Acknowledgements
This research was funded by the National Park Service and the National Center for Preservation
Technology and Training. Its contents are solely the responsibility of the authors and do not necessarily
represent the official position or polices of the National Park Service or the National Center for
Preservation Technology and Training. The authors thank Gary Gordon of NASM and Don Williams,
emeritus of MCI, for fabricating two iterations of the adjustable focal length adapter. Russ Lee (NASM)
and Paula DePriest (MCI) offered valuable discussion.
References [1] Triplex Safety Glass A Vital Necessity. Flight, January 3, 1918, xxvii.
[2] United States War Department, United States War Department Specifications for the Uniform of the United
States Army Special Regulations No. 42, U.S. War Department: Washington, DC, 1917.
[3] C. G. Sweeting, Hitler’s Personal Pilot: Life and Times of Hans Bauer, Potomac Books, Inc.: Dulles, VA,
2001.
[4] L. F. E. Coombs, Control in the Sky: the Evolution and History of the Aircraft Cockpit, Pen and Sword
Aviation: Barnsley, United Kindgom, 2005.
[5] G. B. Watkins, W. Harkins, Industiral & Engineering Chemistry, 1933, 25, 1187–1192.
[6] W. Davis, The Science News-Letter. 1941, 40, 314–315.
209
Book of Abstracts
PL5
The Infrared and Raman Users Group Web-based Raman Spectral
Database
Beth A. Price1*, Boris Pretzel,2* Suzanne Quillen Lomax,3* Marcello Picollo,4*
Charles Davis,5 Andrew Lins,1 Haddon Dine,1 Gabriel Richards6
Philadelphia Museum of Art, US, +1 215 684 7552, [email protected]
Victoria and Albert Museum, London, UK, +44 207 9422116, [email protected]
3
National Gallery of Art, Scientific Research Department, DCL-SR, Washington DC, US, +1 202 842
6763, [email protected]
4
“Nello Carrara” Institute of Applied Physics – National Research Council, Sesto Fiorentino, Italy, +39
3666754973, [email protected]
5
The Dow Chemical Company, Philadelphia, PA, US, [email protected]
6
Endertech Corporation, Torrance, CA, US, [email protected]
1
2
Raman spectroscopy is a well-known powerful technique for the analysis of cultural heritage materials.
The number of Raman systems installed in museum and academic laboratories has grown over the past
decade. Despite this popularity, there remains a lack of readily-accessible, relevant, peer-reviewed,
Raman reference data on known substances to serve as comparisons for samples taken from works of
art and archaeological artifacts.
To help meet this need, the Infrared and Raman Users Group (IRUG) has partnered with the
Philadelphia Museum of Art (PMA) on a project to create a Raman spectral database to be housed
on the IRUG website at www.irug.org. This project is supported by a National Leadership Grant for
Advancing Digital Resources awarded by the Institute of Museum and Library Services (IMLS) to the
PMA in 2009.[1] It is the second database project to be undertaken by IRUG, which previously developed
and distributed several infrared (IR) compilations, the latest containing over 2,100 peer-reviewed
spectra of carbohydrates, minerals and pigments, oils and fats, natural and synthetic resins, and waxes.
When completed, the Raman database is expected to become a similar fundamental resource for the
international cultural heritage community.
The new Raman web-based database software allows users to create personal accounts for online
submission, peer-review, editing, storage, and downloading of data (see Figure 1). As with the IRUG
online IR database, spectra will be submitted in the non-proprietary raw JCAMP-DX (ASCII text)
format, along with supporting information regarding the sample, sampling and data acquisition. After
on-line peer review and quality assurance, spectra will be distributed in the IRUG JCAMP-DX format as
discreet data records.[2] Additional project deliverables include: a software interface for public keyword
and (digital) spectral searches of the database; a searchable Raman bibliography with peer-reviewed,
downloadable, open-source PDF papers; and a glossary of chemical structures and terms.
IRUG has worked with Endertech, a Los Angeles based web design and software development company,
to develop the Raman database and associated functionalities using MySQL® open-source database
management system. Thus far, over 600 Raman spectra have been collected from various contributors
worldwide to form the foundation of the database. Database beta testing and refinement currently are
underway. The target date for launching the database is fall 2013. Individuals interested in participating
should contact their respective IRUG Regional Chair: Beth Price, Americas; Marcello Picollo, Asia and
RAA 2013
210
PL5
Australia; Boris Pretzel, Europe and Africa; or the IRUG Raman Committee Chair, Suzanne Lomax.
Figure 1. Screenshot of redesigned IRUG website showing online Raman spectrum submission
form and interactive spectrum accessed from a user personal account.
Acknowledgements
This project is supported by the Institute of Museum and Library Services; National Center for
Preservation Training & Technology; The Dow Chemical Company, Advanced Materials and Corporate
Information Technology Divisions; Philadelphia Museum of Art; Victoria and Albert Museum; National
Gallery of Art, Washington; and Institute of Applied Physics “Nello Carrara”, National Research
Council. The authors also recognize Abigail Teller, Lauren Klein, Terra Huber, and Heather Brown for
their important contributions.
References
[1] The IMLS is the primary source of federal support in the United States for libraries and museums. Its
mission is to create strong libraries and museums that connect people to information and ideas; to sustain
heritage, culture, and knowledge; to enhance learning and innovation; and to support professional
development. For more information, see http://www.imls.gov (accessed 19/08/2013).
[2] JCAMP-DX (Joint Committee on Atomic and Molecular Physical Data Exchange) is a file specification. For
full information on the IRUG JCAMP-DX protocol, see B. A. Price, B. Pretzel, S. Q. Lomax, C. Davis, J.
Carlson, Revised JCAMP-DX Spectral File Format for Submissions to the Infrared & Raman Users Group
(IRUG) Spectral Database, http://www.irug.org/ed2k/jcamp.asp (accessed 19/08/2013).
211
Book of Abstracts
Index
A
Abagaro 145
Abd El Hady 168, 170
Abdel-Motelib 170
Aceto 73, 96, 191
Acquafredda 155
Adamo 166
Adorni 185
Agarwal 90
Agostino 73, 191
Agresti 164
Aibéo 178
Aliatis 162, 185
Alloza-Izquierdo 157
Almeida 184
Andaloro 164
Anghelone 110
Antônio Cruz Souza 42
Antunes 125
Appolonia 86, 96
Aramendia 130, 138, 140
Araújo de Faria 42, 64, 181
Arteaga 179
Aru 196
Ayora-Cañada 31, 123
Azkarate 140
Azzi 192
B
Bacchini 152
Backus 86
Baldellou-Martínez 157
Baonza 112, 179
Baraldi 52, 54, 56, 73, 164,
191
Barone 192
Barrero 179
Barrocas Dias 121
Barros 145
Basílio 184
Basso 159
Becucci 102
Bellot-Gurlet 33, 48, 138,
175
Bensi 56
Bergamonti 118
Bernard 27
Bersani 35, 118, 152, 159,
166, 185, 190, 192,
205
Bešlagić 68
Bleton 33
Bongiorno 136
Bouzas 112
Brai 184
Brooker 70
Bruder 72
Brunetti 88, 95
Bruni 73, 100, 191
Bucklow 26
Burgio 196
C
Caggiani 155
Caldeira 44
Campodonico 136, 173
Campos Suñol 31, 123
Candeias 44, 121, 125
Caneva 22
Carballo 183
Careaga 64, 181
Carlyle 38
Carnasciali 173
Carvalho 125
Casadio 86, 98
Casoli 35
Castellucci 102
Castro 60, 92, 130, 138, 140
Castro, K. 29
Catarsi 185
Cattersel 66
Centeno 94
Cerasoli 185
Cerc Korošec 82
Chandler 75
Chang 86
Chércoles 112
Cheshnovsky 176
Chillón 116
Ciba 198
Cînta-Pînzaru 108
Claro 121
Clementi 95
Čobal Sedmak 132
Coccato 40, 58, 188
Coentro 154
Colomban 138, 155
Comby-Zerbino 175
Conti 162
Coroado 125
Costantini 35, 152
Craenhals 66
Crivelli 73, 191
Cullen Cobb 208
D
Daher 33, 48
Dararutana 187
Davis 210
De Clercq 150
de Ferri 114
Defeyt 104
De Laet 40
de la Roja 112, 179
de la Torre López 31, 123
Delqué-Količ 175
Demšar 24
De Palma 173
De Torres 116
De Vito 152
Diana 96
Dias 125
Díez 130
Dine 210
Dinis 184
Doherty 88
Domene 31
Domenico 190
Domínguez-Vidal 31, 123
E
Echard 48
Edwards 20
Eixea 183
Elliott 26
Esteves 121
Ewa 50
213
F
Fazio 90
Fdez- Ortiz de Vallejuelo
60, 29, 140, 157
Fenoglio 73, 191
Ferreira 121
Ferrer 116
Finkelstein 176
Fontana 184
Forray-Carlier 33
Francesca 190
Francioli 192
Freguglia 54
Freire 145
G
Gamberini 54
García 140
Gasparotto 52
Gatta 166
Gavrilenko 157
Georgova 178
Germana 190
Ghiara 136, 173
Giakoumaki 29, 157
Gomez-Nubla 138
González-Vidal 134
Graiff 118
Griesmar 51
Gueissaz 200
Gueli 184
Guglielmi 100
Gui 106
Gulmini 86, 96
Gutman 132
H
Hernanz 157
Herremans 150
Hurtado 205
Book of Abstracts
I
Lycke 40
Łydżba-Kopczyńska 198
Idone 86, 96
Invernizzi 159
Ioffe 176
Irazola 130
Isca 118
Iturregui 130
J
Jembrih-Simbürger 110
Jeršek 194
K
Kameranova 178
Kamitsos 160
Karampelas 188
Kavkler 24, 128
Knuutinen 29, 60
Kosec 135
Kramar 132, 194
L
Laakso 60
Lambert 200
Lambruschi 166, 192
Langlois 33
La Russa 159
Lauwers 66, 150, 205
Le Hô 33, 51
Leona 78, 80, 84, 92, 102
Lesar Kikelj 68, 132
Lins 210
Lofrumento 102
Lombard 147
Lombardi 84, 102
Londero 84
Longelin 125
Longobardo 190, 192
Lopes 92
López-Gil 116
Lorenzi 114
Lottici 35, 114, 118, 152, 159,
166, 185, 192
Lubin-Germain 51
RAA 2013
M
Madariaga 29, 46, 60, 130,
138, 140, 143, 157
Madden 208
Madrigal 175
Maguregui 29, 46, 60, 157
Mahmoud 168
Maier 64, 181
Malagodi 159
Malekfar 62
Mangone 155
Marte 64
Martínez 157
Martinez-Arkarazo 29
Martini 136
Massonnet 162, 200
Mazzoleni 192
Medeghini 152
Melo 38, 92
Ménager 175
Menu 51
Mexia 121
Mignardi 152
Miliani 88, 95, 203
Mirabaud 51
Mirambet 51
Mirão 44
Mladenovič 132
Mladenovič 128, 132
Moens 40, 58, 66, 104, 149,
150, 205
Möncke 160
Montagner 38
Montenero 114
Montoro 112, 179
Morillas 46
Motahari 62
Muehlethaler 162, 200
Municchia 22
Muralha 154
Murcia-Mascaros 183
Muscillo 56
N
Neira 140
Neri 90
Nigro 152
Novik 95
O
Oliveira 121, 125
Olszewska-Świetlik 50
Ossi 90
Otero 38
P
Pacheco 181
Pagès-Camagna 51
Palamara 160
Palles 160
Pallipurath 26
Paolantoni 95
Paolo 190
Paolucci 56
Paris 33, 138, 175
Pavlov 178
Pavlova 178
Pellegrino 95
Pelosi 52, 54, 164
Pérez-Pueyo 134
Pétrequin 188
Piasetzky 176
Piccardo 136
Picollo 210
Pitarch 29, 157
Platania 102
Pogliani 164
Poli 162
Ponterio 90
Pontiroli 35
Positano 162
Possenti 162
Pozzi 92, 98
Pozzi-Escot 181
Predieri 118
Pretzel 210
Price 210
Prinsloo 147
Proniewicz 50
214
Q
Qian 75
Quiles 175
Quillen Lomax 210
R
Radi 170
Raneri 190
Reagan 80
Reis 44
Retko 27, 36, 82
Ricci 22, 102
Richards 210
Rizzo1 94
Roldan 94, 183
Romani 95
Ropret 27, 36, 82, 135
Rosado 44
Rosi 95
Rossi 56
Rubio Domene 123
Rubio i Mora 157
Ruiz-López 157
Ruiz-Moreno 116, 134
Rumsey 196
Rusek 198
S
Sala 152
Salcedo 46
Salvioli-Mariani 192
Sambo 185
San Andrés 112, 179
Sanches 38
Santamaria 164
Santoro 51
Saraiva 145
Sawczak 119
Sayed 170
Schade 123
Schreiner 110
Sedlmeier 70
Serrão 125
Seruya 125
Sevilhano Puglieri 42
Sgamellotti 88
Shah 86
Shaus 176
Silva 145, 154
Simon 178
Skelton 26
Śliwiński 119
Sober 176
Sodo 22
Soneira 134
Sousa-Filho 145
Spencer 208
Stella 184
Storme 136
Striova 162
Strivay 104
Špec 27, 36
T
Talebian 62
Tanevska 205
Taravillo 112, 179
Thomas 75
Thongkam 187
Tommasini 90
Toti 54
Trebolazabala 46
Troja 184
Trusso 90
Turetta 152
Tzang 176
Vekemans 150
Veneranda 130, 140
Venuti 190
Verhaeven 150
Viana 145
Vieillescazes 175
Vilarigues 38
Villaverde 183
Viñas-Vallverdú 157
Vincenza 190
Vincze 150
W
Wachowiak 119
Wadley 147
Williams 70
Wondraczek 160
Won-in 187
Wörle 188
Wu 75
Z
Zacharias 160
Zaffino 100
Zannini 52, 56
Ziemann 207
Żmuda-Trzebiatowska 119
V
Vaiedelich 48
Valadas 121
Vandenabeele 40, 44, 58,
66, 104, 149, 150, 205
Vandenberghe 33
Van Duyne 86
Van Eester 66
Van Elslande 54
Van Groenland 66
Van Pevenage 40, 104, 150
Van Willingen 188
Vega Cañamares 80
215
Book of Abstracts
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