renewal of lime wall coverings with lime based paintings

in: RAPHAEL-COMARECH, Compatible Materials Recommendations for the Preservation of European Cultural
Heritage, PACT 58 2000, Atenas, Association of Civil Engenieers of Greece-EC, 2000
RENEWAL OF LIME WALL COVERINGS WITH LIME BASED PAINTINGS:
SOME THEORETICAL ISSUES AND THE CASE-STUDY OF “TORRE DAS
CABAÇAS”, IN SANTARÉM
José Aguiar1 (LNEC – CEUL), T. Diaz Gonçalves (LNEC), and José Delgado Rodrigues (LNEC)
Laboratório Nacional de Engenharia Civil, Av. Brasil, 101, P-1700-066 Lisbon, Portugal
CEUL - Universidade Lusíada, Rua da Junqueira, Rua da Junqueira 188 a 198, 1349-001 Lisboa, Portugal
SUMMARY
The use of lime in mortars, renders and paintings, is slowly being reintroduced in the
construction practice, in Portugal. In this paper we discuss some theoretical implication on the
conservation and “restoration” of urban image in historical towns. We also present a case study
report of a successful use of lime painting for the finishing of a 5-century years old masonry
tower. The work carried out consisted of some laboratory studies and the execution of in situ
test where several limewashes compositions were tested.
1. THE RENEWAL
PRINCIPLES
OF
PAINTINGS
AND
THE
CONSERVATION
The wall coverings of traditional architectonic surfaces, besides their philological importance
for the definition of the architectonic image of the object, are sacrificial layers whose
progressive deterioration allows the survival of the porous materials that constitute the structural
part of the ancient constructions. These types of constructive solutions maintain very close links
with the architectonic expression and with the behaviour of those ancient constructions. When
new concepts and new materials are brought in, quite often requiring the demolition of the old
ones, the behaviour of the object is deeply affected both in its aesthetic performance and in the
corresponding constructive concepts.
By accepting Brandi’s words that “restoration” «… results of the will to reconstruct the critical
text of a work of art»1, then, this kind of intervention, from the theoretical point of view,
acquires new insights: when old coverings are removed with no proper documentation of the
chromatic layers, the complete history contained in the superposed strata is irreversibly erased,
and a significant part of the historic materiality of the object is lost for ever.
The solving (through restoration or renovation) of the urban image of the “historic centres” has
favoured, for a long period, a theoretical approach with a marked “culturistic” trend about the
town colour, about its variation through the years and about the psycho-physiological and
anthropological background of colour perception. Furthermore, it has been focused uniquely on
the cognitive aspects of vision and forgetting all the material side of the problem. This kind of
1
Arch. (FAUTL) / Doctor in Conservation (UE) / Research (LNEC) / Professor (CEUL)
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in: RAPHAEL-COMARECH, Compatible Materials Recommendations for the Preservation of European Cultural
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approach has lead to serious inhibitions when practical questions were put: which colours
should be applied, which materials should be used, which compositions; which paintings and
with which pigments to work with. How to promote the compatibility of new and old covering
systems? How to clean, consolidate, restore and reintegrate the lacunae? The attempt to find
answers to these questions requires research into new ways of interacting between science and
history, between research and conservation project, between conservation and construction.
Presently, new techniques for the solution of some major problems of ancient renderings are
known, namely as regards loss of adhesion and loss of internal cohesion. These techniques are
more or less well mastered by the “conservation engineering”, but it is necessary to assess the
feasibility of their application to more current and less “monumental” interventions, namely in
wide interventions of urban conservation.
To a certain extent, we could say that the intervention philosophy has substantially changed. In
the field of theoretical reasoning, the systematic renovation has given way to its antagonistic
position. Today, the renovation of the coverings of ancient buildings is accepted only when its
practical conservation is unmistakably proven to be unfeasible from the technical and economic
viewpoints.
However, the recognition of the importance of the architectonic surfaces as relevant components
of the authenticity (either historical or artistic) of historic buildings is a relatively recent
evolution of the conservation praxis in urban landscapes. Only in the 80s and mainly in the 90s,
countries such as Italy, UK, Austria, France and Germany have launched some urban
conservation interventions with systematic preservation of painting, finishing and original
covering in ancient constructions. Whenever conservation was impossible, detailed studies of
the old solutions were carried out, witnesses were preserved and new coverings were applied
ensuring that the materials used and the performances expected would be kept as similar as
possible to those of the previous existences.
As Paul Philippot2 stated, the main critical problem faced by experts when dealing with results
of researches about colour and historical paints, in their different technologies and surfaces –
especially when handling the archaeology of material evidence – is to determine to what extent
their esthetical function, in reconstructing the interpretation of a certain urban image, can still be
re-established or not. The attempt to find an answer to that issue reminds us, on the one hand,
of Cesare Brandi’s “restauro” theory, which was based on the potential unity of fragmented
works. On the other hand, it reminds us of the problem related with the warranty of
authenticity, which leads technicians to limit their interventions to the potential capacity of the
remaining elements that have been effectively preserved.
The actions referring to urban conservation imply, as in other repair work, a careful critical
analysis. In fact, through that analysis, the historical town, similarly to any work of art, must be
seen and interpreted in all its complexity and as a whole entity. The problem is theoretically
complex, but as Paul Philippot and Piero Sanpoelesi3 highlighted, is not significantly different
from the critical problem related with any conservation (by restoration) action. The solution of
those dilemmas depends on the careful thinking of the values at stake, on the authenticity of the
original creative moment and on all the values added by time.
A safekeeping intervention will always be a transforming one, thus implying awareness of the
historical legacy, as well as the perfect consciousness of the actual time of the very intervention.
The highest disciplinary difficulty lies in determining solutions that will be more than: casual
actions, the mere adoption of the latest fashion, the temptation to adopt a philological rewriting
in a new format, and finally, the re-establishing of a somewhat mimetic or kitsch historicism.
The fact of our being aware of an excess of ambition in repair projects in the past, does not
necessarily lead us to exclude presently the strategic importance of the principle of “minimum
intervention”, regardless of the architects’4 opinion.
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in: RAPHAEL-COMARECH, Compatible Materials Recommendations for the Preservation of European Cultural
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Eventually, there will be a moment when the paints will no longer be able to fulfil their
functional capacity as esthetical envelops and protecting coverings, due to the technical and
economic unfeasibility of their preservation. That is why it becomes essential to carry out new
studies about ancient technologies and covering materials, so as to assess the possibility of
reusing them, both in occasional repair actions and in more comprehensive repair works, when
dully justified.
2. THE PORTUGUESE SITUATION
Most projects that continue to be developed in the Portuguese historical urban nuclei prescribe:
(i) the removal of old coverings and replacement by materials developed for new constructions
(usually renders on basis of cement mortars and synthetic paintings), which consequently raises
problems related with the aesthetics and compatibility of these materials with the old masonry;
(ii) aesthetical modification of the architectonic surfaces using the modern impermeable and
“self-washable” synthetic paints, which are seldom appropriate in terms of colour.
The occurrence of anomalies, particularly at the wall coverings level – which take place very
often in recent works – are too frequent. Many of these works were and still are subsidised by
public funds.
Surprisingly, in the study of the relations between colour and architecture, it was found that in
Portugal, and on the contrary of most European countries, there were no analyses about the
impact of colour on the projects related with the esthetical “presentation” of the patrimony.
This is particularly applied to the historical materialising of “colour”.
Initially, it was considered that it would be possible to recover the necessary knowledge from
oral transmission, through enquiries to old construction masters. Nevertheless, it has been
proved that presently it is very difficult to find such technicians whose practical knowledge has
not been corrupted by (minor or significant) alterations of the ancient techniques. This fact
leads us to assume that more than a half-century of construction methods has already been
affected by industrial “tradition”. Consequently, we are forced to use science and the
(re)transmission of all the learning acquired by it, in university courses, so as to compensate the
loss of the so-called traditional knowledge.
The conjugation of the old construction with the recent industrial technology places difficulties
that result in some operational, functional and esthetical incompatibilities. That is why reusing
traditional technologies is an advisable choice. Presently, the knowledge of culture and of local
constructive characteristics, materiais and techniques and the definition of the repair solutions
based on the ancient methods are considered as essential factors. Such factors should be taken
into account when performing rehabilitation and repair works, when filling in gaps and also
when considering the possibility of adopting reintegrating actions. This serves to explain the
interest in (re)using lime as binding material, taking advantage of its relation between cost and
quality.
In Portugal, comprehensive experimental studies must still be carried out, so as to provide more
accurate information about the effects of the type of technologies referred to above on their
(re)application throughout the country. Some first research works carried out at LNEC pointed
at the great interest of testing the effects of reintroducing these ancient technologies.
Afterwards, LNEC researchers, such as the one included in the second part of this paper
developed several case studies.
3. THE CURRENT PRACTICE
The conservation of colour, surfaces and coverings will always be a commitment. But the very
conservation is also the art of commitment. In this field, the practical application of the science
has some limits: the expression of limewashing is neither definable in a comprehensive way,
neither likely to be reproduced just through its chromatic co-ordinates. In order to reproduce a
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limewash there are other parameters difficult to quantify, which must be taken into account (as
Scarzella and Natale studied5). Some of these parameters are: the texture and finishing used; the
transparency level; the chromatic variations related with the transparency and reflectance
spectrum of pigments; the variation and vibration of colour due to the different materials and
methods used; the various stereotomies of the application procedures of the different types of
porosity, which give either homogeneity or heterogeneity to the surfaces; etc.
Even in a simplified approach to the basic principles and colour theories, it can be verified that
due to the phenomenon of conditionally similar colours, it is almost impossible to reproduce
effectively the exact aspect and colour of an original surface (moreover when the surface has
been submitted to time effects). All this (until the present moment) regardless of how
sophisticated the modern paint technologies are.
In fact, neither just an effective analysis nor a well-organised diagnosis is enough to conform
the corrective actions to be developed on the “facies” of the historical town. There will always
be some shadow zones that require other type of complements, which have mainly a critical
nature, being therefore related with design aspects. Ever since almost half a decade of intensive
use of Portland cement and modern paints (acrylic, vinylic, etc.) in Portugal, it is becoming
almost impossible to find ancient buildings presenting material evidence that will allow us to
reconstitute accurately their presentation throughout the years. Very often, the pure and simple
information void is the sad reality.
That is why there is an urgent need to develop new methodologies, namely those capable of
operating within the new disciplinary field that has been designated as “environmental colour
design”. Consequently, new and fascinating research paths in architecture are emerging,
simultaneously with new possibilities in reusing ancient technologies, such as the so-called
mineral paints.
The parameters of the chromatic performance of the ancient paint solutions, now converted into
an essential value in perceptive and esthetical terms, are almost impossible to reproduce with
techniques and materials that are not physically and chemically similar. This fact places many
doubts about the use of most modern solutions, despite the existence of new and promising
possibilities (such as some types of mineral paints). Therefore, it becomes essential to carry out
the scientific recovery of “limewashing techniques”. This is justified from various points of
view: (i) constructional, due to the high compatibility with old buildings; (ii) aesthetical,
because it is a natural form of ensuring the harmony with the territory and the traditional
envelope (roofs, floor coverings, language of the traditional architecture); (iii) historical,
because it integrates all the interventions in a single denominator, in a continuum that goes
beyond the modern technological reasoning.
4. THE CASE OF WHITEWASHING THE “TORRE DAS CABAÇAS”
(TOWER OF THE CLOCK) IN SANTARÉM
Relógio (or “Cabaças”) Tower was classified as national monument in 1928. The Tower is a
rock masonry construction, reaching 23 meters, from the ground to the cupola which supports
the bells that marked all the important moments of the town’s life.
The tower was designed to have, as outer cover, a mineral render made of lime and sand,
finished with whitewashing. Vestiges of this first coverings systems subsist protected behind an
abutment, assumedly constructed shortly afterwards the original construction, as reinforcement.
The historical iconography, mainly collected in the last quarter of XIX century, as in the first
photographs of the tower (in the same period), proves the continuity of this form of presentation
of the monument6.
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in: RAPHAEL-COMARECH, Compatible Materials Recommendations for the Preservation of European Cultural
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Fig. 1, Fig. 2 and Fig. 3 – The Torre das Cabaças, before and after renewal (detail).
Between 1932 and 1934, the Direcção Geral de Edifícios e Monumentos Nacionais (DGEMN,
Portuguese entity then responsible for the politics, projects and the execution of works in
classified monuments) decided to restore the Tower, by removing old mortars and carrying out
renewal with similar techniques. The authorship of the project was from Arch.º António Couto7
and it is well documented8. Nevertheless, the renderings have never again been restored to their
initial configuration.
More recently, during a multinational conservation project (involving Greece, Italy and
Portugal) partly subsidised by E.C., “Projecto Sanveral”, it was decided that the Tower should
be restored and and to proceed with its adaptation for a time museum9.
The Tower has enormous impact on the urban image of the historical town of Santarém and any
change mobilises the sensitivity of the population. Therefore its restoration would have to be
carried out with great care and great exemplarity.
The decision to apply new coverings was due to the will to achieve the restitution of a
presentation concept linked to the historical and artistic reality of the monument. It was also
justified by the extensive degradation of the rock masonry, which tended to grow (with the
deterioration of the masonry mortars and stones, mainly by weathering).
The Municipality of Santarém (CMS) asked LNEC’s support on the specification of materials
and technologies to be used in the restoration of both the mortar’s and finishing.
For constructive and aesthetic reasons, it was decided to use materials similar to the original
ones, and that the mortar and finishing should be restored to their original configuration.
The solution purposed by LNEC for the Tower coverings was a lime render (of dry hydrated
lime and a mixture of pit sand and river sand), applied in thin layers, in the necessary number to
obtain regularization of the wall surfaces.
The proposed solution consisted of one mortar, constituted by hydrated lime powder and an
local sand (a mixture of yellow argillaceous sand and river sand), applied in fine layers, the
necessary ones to obtain regularisation of the surfaces of the wall. The work done by LNEC for
the definition and execution of this render was described in a previous paper10. In the present
paper, we will focus the subsequent painting.
The selection of the painting to apply over the lime render had in sight the protection of the
underlying mortars, as well as the restitution of an adequate reading of the monument, making it
possible and simpler the future maintenance of the Tower coverings.
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The available workers lacked specialisation, and the contractor was not especially oriented to
conservation. He didn’t have, also conservating-restoring technicians to ensure the necessary
following of the works.
The first project decision (the project was co-ordinated by CMS technician’s) consisted of
seeking paintings similar to the traditional lime mortars colours (earth and clear tones), with
some heterogeneity in the aspect and texture.
By configuring the best alternative, LNEC considered the application of a whitewash painting,
very fluid and adequately coloured with a mineral pigment (a natural earth or, in its absence,
hydrated iron oxide).
Therefore, LNEC recommended whitewashing to the volumetric relation of 1:2 (lime putty and
water), with a small percentage (10 % in relation to the volume of lime putty used) of an acrylic
resin in aqueous dispersion (Primal AC33), usual for this kind of applications.
The involvement of LNEC included the recommendations for the execution of the painting, in
terms of composition and technique. It also included the definition and the accompaniment of
“in situ” tests with distinct mineral pigments for refining the colour of the limewash. It also
included the accompaniment of the final execution, in the Tower, of the painting.
It was also carried out a laboratory test campaign to evaluate some relevant features and
characteristics that could condition the future performance of this type of paintings.
Fig. 4 and Fig. 5 – Preparing lime paintings, with distinct mineral pigments, and “in situ” applications.
The experimental work done (finishing for expressing itself in an substantially more widened
inquiry work) is described in the corresponding internal report of LNEC11. It was analysed:
-
(i) The above described limewash with acrylic resin;
-
(ii) A silicate painting, commercialised in the Country;
-
(iii) A limewash made with good quality lime putty;
-
(iv) A limewash made with the same lime putty but including also a small percentage of
casein.
Tests of water vapour permeability, capillarity, behaviour when submitted to soaking and drying
cycles, resistance to the development of fungus, and artificial aging by rain / radiation (IV)
cycles were performed in laboratory. The tests carried out, the results obtained and the
corresponding conclusions were extensively described in an internal report of LNEC12.
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The tests lead to the conclusion that the use of both additives (casein and acrylic resin)
originated important reductions in the capillarity coefficient. These additives also modified, now
by improving it, the ductility of the paintings (capability to become deformed without
breaking), especially in the case of the casein.
The results of this experimental study, relative to the whitewashing with acrylic resin, were
globally positive, supporting the choice of this solution for Relógio Tower. They made it
namely possible to verify that the inclusion of the acrylic resin, in such a low percentage, does
not seem to affect (so) negatively the painting permeability to water vapour.
The “in situ” tests consisted in applying different colour limewashes over a lime mortar panel of
about 1,5 m height for 5 m length.
Some mineral pigments, available in the market, were tested. Other experiments were carried
out empirically in an attempt to reproduce some colours with pigments extracted from the local
yellow sand and therefore restoring the use of a traditional practice.
The pigments extraction was performed in accordance with the following technique: (i) the sand
was washed (about 1 l of sand for 10 l of water), in order to separate the argillaceous fraction
from thick particles of the sand; (ii) the mixture was decanted and these larger particles
eliminated; (iii) the resulting mixture was subsequently filtered through a cotton cloth, to
remove the excess of earth soil.
The complete operation of extracting the earth pigment was also supposed to include the final
evaporation of the water to get a very fine dust (the final pigment). This was not, however,
accomplished in this case, due to lack of time and also because this was only a preliminary
experience intended to evaluate the colour that we could obtain and the viability of the method.
However, it could be observed that this technique requires the use of, since at least in the case of
the sand used, its coloration power was very low.
In colour terms, the best results (nicer and near the HUE intended) were achieved with the
pigment extracted from the sand. However, in qualitative terms, it could be observed that this
technique requires the use of higher pigment percentage in the limewashes since, at least in the
case of the yellow sand used, its coloration power was very low (substantial lower than the one
of the common commercial pigments).
It was therefore decided to use a hydrated iron oxide of current commercialisation instead of the
sand earth pigment. This decision was mainly due to the possible negative consequence in the
durability of the limewash of such a large percentage of pigment. It was also due to the
difficulty of guaranteeing, with the sand pigment, a certain chromatic homogeneity in so
extensive surfaces as the foreseen ones.
In the evolution of the project it was decided to modify the initial presentation concept and to
assume the (white) natural colour of the whitewash, since it existed more historical evidences
and justifications for this option.
The intervention also included the restoration of the Tower cornice and upper vault through a
simplified reconstitution of the original (destroyed during the 1932/34 intervention). The CMS
architects have chosen to mark and distinguish this zone of the external surface of the Tower,
having added to the whitewashing a large amount of natural earth colour pigment.
The final limewash (whitewash with Primal AC33 and a little quantity of pigment, just to avoid
the excessive whitish lock) was applied in two to four crossed coats - according to the place. An
adequate time of drying of at least 24 hours was guarantied between each two coats.
The painting of the Tower was completed during the winter of 1998/99. The results are, until
the present moment, and after almost two years, very encouraging, as there are not any
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significant signs of degradation. Some spots that can be seen on the limewashed surface result
from an inadequate conduction of the rainwater, as the necessary constructive details (dripping
pans, etc.) were not always properly considered in project.
5. CONCLUSIONS, PROPOSALS
PERSISTING PROBLEMS
AND
PRESENTATION
OF
SOME
A few of the traditional specialities, which are nowadays necessary for carrying out repair
works in historic urban centres, are almost non-existent (some of them, have even disappeared a
few dozen years ago). Presently, all efforts must be directed to “reconstruction” of knowledge
rather than to recovery, particularly as regards the architectural and urban patrimony, because
some of the former capacities cannot be found anymore in the world of production and work.
In this context it is essential to promote, as a key-element, the direct involvement of restorer’s in
urban conservation and repair interventions, concerning both the development of the projects
and the mediation between the co-ordination of the project and the work (simultaneously
supporting an activity that is still rare in Portugal). As a consequence, it is important to
reformulate the present Portuguese conservator’s training system, which stresses the importance
of the technicians that are devoted to preserving and repairing of the mobile patrimony, and
almost completely disregards the training of restorer’s capable of carrying out architectural and
urban repair works.
The actions related with the colour design within the architecture and the historical town, other
than the mere intensive reformulating of the reality to which they are applied, must be limited to
the minimum necessary to carry out a critical re-structuring of the basic facts of the urban
pictorial image. This is achieved by re-establishing the relations between the structure and the
syntax of the individual architectures with a collective scenic function of the urban network.
The application of the theories developed to the filling in of lacunae, in the field of repair of
murals, should be extended to other interventions at this level. In addition, and provided that the
patterns (palettes) are known with a fairly high accuracy, it is always possible to reduce the
impact of voids, through schematic integration strategies, without resorting to invention or
artifice and by re-establishing the communicating function of the architecture in its urban
context.
Therefore, one must also invest mainly on “current maintenance” and limited repair procedures,
rather than on extensive and “maximalist” actions intended to renovating with a simply
replacing character, (which are always politically chosen, due to their feasibility). Such fact
implies acting within a very wide range of possibilities, at various levels and in successive
stages, from mere cleaning – which includes minor retouches – to the various levels of
integration in the filling in of lacunae, until the renewal of significant parts of walls, in which
the possibility of reading has been irrevocably affected, by re-establishing a historical and/or
contextual logic.
The reuses of limewashing has been experimented for more than 20 years all over the Europe,
and whereas in some cases, those attempts have been well succeeded, in other cases however,
have produced not so god results. The particularly worrying facts proved to be the low
durability of limewashing, its low resistance to dirt and the extensive conversion of lime into
gypsum, mainly due to highly polluted atmospheres and acid environments, as is the case of
Lisbon and of some urban historical nuclei of large European towns, especially in zones with
heavy traffic (see also P. Scarzella and P. Gaspareli´s studies for Turin)13.
Those problems point to the need of studying more closely the performance of coverings and
limewashes in that type of urban environments, so as to find new ways of increasing their
durability and their pollution resistance, namely by developing research into admixtures. In
highly polluted environments, it may be necessary to use alternative technologic solutions, such
as the new mineral paints, based on pure potassium silicates. Those paints are able to reproduce
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some of the aesthetical characteristics of limewashes, especially when the same type of
inorganic pigments of local origin (earth) is used (if they are compatible with potassium
silicate), being simultaneously possible to evaluate their aesthetic and effective performance in
the ageing process.
Many of the traditional materials are nowadays unfeasible due to basic security and health
reasons (for example, some pigments). When reusing the technologies of lime, there are
important technological and normative approach levels that require an urgent articulation either
at international or, at least, European level. It is therefore important to enlighten various
shadow-zones referring to the performance requirements of technologies related with coverings
based on mineral binders. Consequently, it is also essential to use specific patterns in
conducting tests on the performance of mortars and limewashes, because the methods currently
used were basically developed to test modern products. For instance, as regards lime techniques,
and considering the fact that the carbonation process is slow, it may be inappropriate to carry
out mechanical strength tests on lime mortar samples …at 28 days!
Both for limewashing and mineral paints, it is essential to find some formulations that may be
coloured with inorganic pigments of regional origin. Therefore, considering that Portugal was
one of the highest producers of earth in the past, and that it used to produce natural pigments
with a quality that had been praised since the Roman times (cited by Plínio14), it is necessary to
study again the sources of the pigments traditionally used in this country. Nevertheless, ever
since the 50s, the main production sources in the country have been closing down.
Internationally, there has been also a quick decrease and even disappearance of the inorganic
pigment production. That type of pigments has been increasingly replaced by organic pigments,
which very often have a low compatibility with limewash techniques, and which have proved to
have, in their use in Portugal and due to the high insolation existing in this country, a low
durability of colour.
The use of smooth coverings as finishing renders (3mm of pure lime putty, or lime putty with
very fine sand, or rock powder) and with pigments, replacing paint in the Portuguese historical
architecture, is significantly wider than it had been considered before. The types of surface and
texture that are likely to be obtained with these coverings are very specific and difficult to
reproduce by the mere smoothing of renders. Therefore, it becomes essential to reintroduce that
type of techniques, especially in preserving and rehabilitating actions.
Special reference must be made to the fact that the colour depends directly on the procedures of
transmission of light: textured surfaces reflect light in a diffusive way, whereas smooth textures
reflect light in a more direct way. Consequently, there is a direct relation between light, type of
surface and colour that is why it would be contradictory to specify colours and its materials and
fail to specify the type of textures and covering surfaces in conservation actions.
The described case study it is only one of diverse cases of coverings renewal and restoration,
appealing to renders and paintings based on traditional solutions, in which the LNEC is
collaborating with diverse Portuguese entities linked to the conservation of the architectural and
urban heritage. LNEC is also pursuing several research programs, at a national and at an
international level, trying to improve the available knowledge in this field.
BIBLIOGRAPHY (not cited on references)
AGUIAR, José, Chromatic studies in urban conservation. The case of Portugal, (PhD thesis), Évora,
University of Évora, 1999 (in Portuguese).
AGUIAR, J., Studies on colour and urban conservation, in Encontro Planos de Cor e Centros Históricos,
Museu Arqueológico de Conimbriga, Coimbra, IPPAR, 1999, (in Portuguese).
GONÇALVES, T. D.; VEIGA, M. R., Study of the external renders for Jesus Convent, in Setúbal.
LNEC, Lisbon, LNEC, Oct. 1997. Internal report 236/97 (in portuguese).
9
in: RAPHAEL-COMARECH, Compatible Materials Recommendations for the Preservation of European Cultural
Heritage, PACT 58 2000, Atenas, Association of Civil Engenieers of Greece-EC, 2000
MARGALHA, M. G., The use of lime, in plasters and renders, in Alentejo, Évora, 1997. MSc. Thesis,
University of Évora (in portuguese).
PRICE, N.; TALLEY Jr., M.; VACCARO, A. (ed.), Historical and Philosophical Issues in the
Conservation of Cultural Heritage, Los Angeles, The Getty Conservation Institute, 1996.
RODRIGUES, J. A., A arquitectura da Torre do Relógio, Santarém, Dezembro de 1997.
RODRIGUES, D., Colours And Textures In The Conservation Of Stony Surfaces, in International
Seminar on Colour and Conservation of Architectonic Surfaces, Lisbon, LNEC, 1999 (in Portuguese).
REFERENCES
1
Strengthening this thesis: «Il restauro deve mirare al ristabilimento della unità potenziale dell´opera d´arte, purché
ciò sai possibili senza commettere un falso artistico o un falso storico, e senza cancellare ogni traccia del passaggio
dell´opera d´arte nel tempo». Cesare Brandi, Teoria del Restauro, Piccola Biblioteca Einaudi, Turim, 1963, p.8; or
Michele Cordaro (ed.), Cesare Brandi, Il Restauro, Teoria e Pratica, Roma, Editori Riuniti, 1996.
2
The main point about the issue can be found in the article: Paul Philippot, La restauration des façades peintes: du
problème critique au problème technique, in Facciate Dipinte, conservazione e restauro, Atti del convegno di studi,
Genova, Sagep Editrice, 1982, pp. 105-107.
3
Paul Philippot, ob. cit., (1982); Piero Sanpaolesi, Discorso sulla metodologia generale del restauro dei monumenti,
Florence, Editrice Edam, 1973.
4
Manfred Koller’s historical studies proved that the greatest losses of historical substance - as regards paints, plasters
and murals (either external and internal) of historical interest which in some cases have actually disappeared -, such
losses were verified in Austria mainly in State monuments, which were managed and administrated by particularly
competent technicians (of the riegliane school and being in close contact with the best European schools of thought,
such as the Italian school) and having a high economic capacity for promoting “repair” works. See M. Koller,
Historic facades in Austria: Examination and treatments, 1970-1990, in Seminar on Building Surface Treatments,
Helsinquía, Museovirasto/ Rakennushistorian Osasto/ICCROM, 1991, p. 38.
5
Paolo Scarzella; Pietro Natale, Terre coloranti naturali e tinte murali a base di terre. Monografie e catalogo delle
collezioni di terre coloranti a di campioni di coloriture a base di terre allestite al Politecnico di Torino, Turim,
Stamperia Artistica Nazionale, 1989.
6
Jorge Custódio, Tower of the Clock, Iconography and symbol, in Catálogo da exposição do Projecto SANVERAL,
Dia internacional dos museus, Santarém, CMS, 1997 (in portuguese).
7
On the subject: Jorge Custódio e José Augusto Rodrigues, A cimalha e arquitrave da torre das cabaças de santarém,
Parecer, CMS,, n. p., s. d. Also A. Couto, Reparation works of Cabaças Tower, Direcção Geral dos Edifícios e
Monumentos Nacionais (DGEMN), October 1932, Memória. (in portuguese).
8
On the subject: Jorge Custódio e José Augusto Rodrigues, A cimalha e arquitrave da torre das cabaças de santarém,
Parecer, CMS,, n. p., s. d. Também A. Couto, Reparation works of Cabaças Tower, Direcção Geral dos Edifícios e
Monumentos Nacionais (DGEMN), October 1932, Memória. (in Portuguese).
9
An Advisory Scientific Committee including J. Delgado Rodrigues, V. Ferreira Jorge and João Appletton provided
a permanent support to the municipality and to this project.
10
More details on this subject can be found in T. Diaz Gonçalves and J. Delgado Rodrigues, Study of Lime
Renderings for the rheabilitation of traditional constructions, a case study, COMARECH Workshop of Istambul.,
October, 2000.
11
Teresa Diaz Gonçalves, Lime wall coverings for the rehabilitation of Relógio Tower, in Santarém, Internal Report
194/00, NCCT, Lisboa, LNEC, 2000 (in Portuguese).
12
C.f. Teresa Diaz Gonçalves, ob. cit., 2000.
13
Paolo Scarzella; Paolo, Gaspareli, Available technological systems for painting, repainting, and plaster integration
of historical buildings. Duration, compatibility and use limits, in Dealing with defects in building, vol. 2, Varenna,
1994.
14
Plínio, S., Della Storia Naturale Libri XXXVII, Veneza, Tip. G. Antonelli, 1844.
10