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the online magazine No. 7, October 2008
e_conservation
edit
oria
l
One-Year Anniversary
In October 2008 e_conservation magazine celebrated its first year of existence, thus it is time for us to sum up our publishing experience. Looking back at the 6 issues we have published I can see that conservators do indeed have much to say. There are so many interesting things concerning our experience as professionals that are worth being made public and our task is to do just that. It has not been easy, but I can see an ongoing evolution in our approach, which is molded and shaped by experience. I believe that during this year our team, collaborators and committee members have done an excellent job. I want to thank them for having invested continuous efforts and for helping to maintain a high publication standard. On behalf of our team, I wish to thank all authors who submitted their papers during this last year to e_conservation magazine, and for sharing their knowledge and work with other professionals in the field. Often, their collaboration has continued and become a permanent and valuable support for the magazine. Obviously without you, our readers, and the website community members the magazine would not exist. I wish to thank you all for your numerous downloads and for the positive feedback, ideas and suggestions that we have received.The one-year anniversary is also the best moment to sort out our 2009 plans. On the practical level we are preparing to implement, next to the pdf format of the magazine, the html format that will allow the content of the magazine to be read online. On a more general level we are planning to give priority to the publication of research results, wishing to make new information available in a way which is easily accessible by everyone. We came to this conclusion after seeing that there is an acute need for a better synchronization between actual performed research, access to the outcome and current conservation practices. Plenty of institutions and researchers around the world perform high profile and relevant studies using some of the most advanced technology available, however, the transition between this research and the daily conservation treatments is still a difficult terrain. I believe that by continually publishing and giving free access to information we can help to fill in this gap. Conservators are aware that conservation is not a static field but a very dynamic one. Even though we apply our best knowledge to the conservation problems we face everyday, we also tend to implement the methodologies and treatments that we are most comfortable or familiar with. This reminds me a presentation I recently attended, where the Italian researcher Piero Baglioni shared his experience in helping conservators to establish the best approach to conservation practice. He pointed out a very important aspect: often the conservator may tend to damage the work of art by introducing harmful products or methodologies for lack of a better solution in cases where some sort intervention is unavoidable. This gap between the recent technological advances and our practice as professionals must be overcome and this is what drove us in the first place to publish the magazine. Controversies aside, I believe that free information distribution to professionals in an easy to access way such as the internet is what the future should hold for us. All we have to do is to want to share and learn.
Rui Bordalo,Executive Editor
e_conservation
NEWS 6
41
ARTICLES
CASE STUDY 50
73BOOK REVIEW
21
CONFERENCE REVIEW
Projects of T. K. McClintock
Conservation of Fine Art and Historic Works on Paper
9 October 2008, Lisbon, Portugal
Reviewed by Rui Bordalo
EITEC 2008
The 3rd International Meeting of Technologies Applied to
Museology, Conservation and Restoration
23-24 October 2008, Porto, Portugal
Reviewed by Teodora Poiata
ANNOUNCEMENTS
UPCOMING EVENTS
November - December 2008
CONSERVATION SCIENCE
The Visible Image Is Not Always Correct
The Differentiation of Layers by Optical Microscopy in
Samples’ Cross Sections
By Carolina Barata, António João Cruz and Marta Ferro
TECHNOLOGICAL STUDIES
The Church of Voronet Monastery
Technical Considerations of the Mural Paintings
By Ioan Istudor
MATERIAL STUDIES
Forecast of Chemical Aging and Related Color Changes
in Paintings
By Boris Zilbergleyt
RED MAITREYA TEMPLE - LEH, LADAKH
Mural Conservation Project (Part 2)
- A Tibet Heritage Fund Project
By Anca Nicolaescu and André Alexander
Conservation of Plastics
Materials Science, Degradation and Preservation
Reviewed by Brenda Keneghan
EVENTS
10
26
e_conservation 5
INDEX
16
17
new
sPROJECTS OF T. K. MCCLINTOCK
9 October 2008Lisbon, Portugal
National Museum of Ethnology
Organised by: Área de Papel do Departamento
de Conservação, Instituto dos Museus e da Conservação (IMC)
http://www.ipmuseus.pt/
e_conservation
On the occasion of the visit of the American con-
servator T. K. McClintock to Portugal, the Paper
Area of the Conservation Department of the Insti-
tuto dos Museus e da Conservação (IMC) organised
on 9th October 2008 a conference to present some
of his projects. T. K. McClintock is the director and
founder of Studio TKM, a private conservation
enterprise located in Boston and specialised in
the conservation of fine art and historic works
on paper. The conference, divided in 4 individual
lectures, turned out to be one of the most inter-
esting I have attended so far: not only were the
projects outstanding, but the author proved to
be a very good speaker, retaining the audience’s
attention for more than 6 hours.
The event was opened by Isabel Raposo de Maga-
lhães, the vice-director of IMC, who welcomed T.
K. McClintock and briefly presented to the audi-
ence his background and professional experience:
he holds a master’s degree in Conservation of
Historic and Artistic Works from the Cooperstown
Graduate Program, and graduated from Boston
College with a bachelor's degree in Art. After he
worked over a decade at the Northeast Document
Conservation Center he established his private
studio, specialised in the conservation of fine
art and historic works on paper.
Mr. McClintock started his speech with a brief pre-
sentation of his private studio, which has been in
existence since 20 years and is specialised on the
conservation of works on paper. An interesting
aspect is that since the beginning the studio has
been working with the same people, which is
important for an effective team work based on
"institutional memory", that is the accumulated
Conference based on 4 lectures:
. Observations on the Mutual Influence of Asian and Western
Paper Conservation Practices;
. Compensating for Losses inHistoric Wallpapers;
. Globe Conservation;
. The Drawings of Frank Lloyd Wright: Observations on their
Conservation.
Reviewed by Rui Bordalo
e_conservation 7
CONFERENCE REVIEW
team experience. Several other aspects that are
important to achieve a successful private conser-
vation practice were underlined: the good com-
munication among the conservators in the studio;
the communication with colleagues in the same
profession and with clients; the constant training
by attending conferences and programs; and the
research of collections and exhibitions in order
to gain knowledge on practices and materials as
well as familiarity with objects that are in good
condition.
80 percent of Studio TKM’s works come from public
institutions and the rest from private collections.
Their projects, half Asian and half western, are
frequently very large, taking several hundreds
of hours of work.
An impressive number of case studies were
presented during these 4 lectures.
The first lecture - Observations on the Mutual Influence of Asian and Western Paper Conser-
vation Practices - focused on how conservation
methodologies greatly benefit from reciprocal
share of experience.
Mr. McClintock took a step into the past and re-
viewed some of the few available documentation
resources as publications or training opportuni-
ties in the field of paper conservation thirty years
ago, showing how the professional exchange has
developed slowly but gradually with time. One
important documentation resource for the author
was the film The Art of the Hyogushi, produced
by the Freer Gallery, which presented in detail
the conservation treatments executed by Takashi
Sugiura and his colleagues on several works on
paper. Even if today the methods described in
the movie are no longer in practice, for the 1970s
they had an impressive impact on the western
professionals. The fact that information about
Chinese and Japanese studio practices started
to spread was an important step in the develop-
ment of paper conservation. Western professionals
have learned from the experience of Asian paint-
ings conservators on how objects respond to
treatments, from their confidence in executing
large scale projects as well as from the quality of
materials, tools and procedures they are using.
With time, the communication difficulty between
these two cultures was overcome, western conser-
vators going to Japan and Asian conservators
coming to the west to mutually benefit from
working and teaching experience. Today, Asian
painting conservators benefit from research
results and western developments such as the
suction table for consolidation, synthetic resins
consolidants, and cellulose ether adhesives among
others. On their turn, westerners adopted Asian
tools and supplies such as brushes, wheat starch
paste and Japanese papers, and mounting, lining
and reinforcement procedures. Above all, west
conservators have improved their knowledge on
the Asian objects, and have come to understand
that there are many differences between Chinese
and Japanese art objects, between their produc-
tion technologies and implicitly, between their
conservation methods and traditions.
Mr. McClintock continued explaining the techno-
logic differences between a scroll and a screen
painting, showing that besides the inherent con-
struction of the objects, their purpose and role
greatly influences the exposure degree and thus
their state of conservation. It was also emphasized
that Asian works are seen as adaptable and their
Photo by Aline Oliva
8 e_conservation
CONFERENCE REVIEW
method of display can often be changed: hand-
scroll sections, for example, can be remounted
as hanging scrolls while hanging scrolls can be
remounted as folding screens. Unlike for other
works of art, these changes are seen as part of
an already accomplished change of circumstances
and not as a compromise to the integrity of the
object. As a general conservation observation,
the author has noticed that Asian paintings, even
if not uniform in execution or condition, show a
more regular pattern of problems than those
encountered with western works. The rapport
between the complexity of a treatment and the
time spent by the conservator to perform the
intervention was also discussed, as well as
balanced solutions for conservation treatment.
Among the interesting case studies presented,
the intervention performed on a 17th century Ming
copy on silk was described. The painting was
mounted for display at Taliesin, the summer home
and studio of Frank Lloyd Wright in Wisconsin.
A particularity of this treatment was the partial
removal of the linings but the maintenance of
the so called "life layer" - the paper layer behind
the silk. Also, the remounting was done using a
honeycomb panel, which is resistant to contraction
strength and allows only one side covered with
layers of paper. This was done in order to fit back
the painting into the original niche of the wall.
In the end of his first lecture, Mr. McClintock
paid tribute to Mr. Sugiura, who passed away in
2005 and with whom he had the honour to work
in 1984.
The second lecture - Compensating for Losses in Historic Wallpapers - dealt with the complex task
that conservation of wallpapers is. In this case
the conservation procedures for Asian and west-
ern works differ a great deal. There are several
factors that make this type of conservation par-
ticular: the large size of the papers, the high
level of exposure to degradation factors, the
time consuming treatment process and the dif-
ficulty of treatment due to a limited access to
the back of the wallpapers. A first arising issue
concerning the conservation project is whether
the treatment can take place in situ or the paper
must be partially or fully dismantled and treated
in the studio.
Another very important factor that comes into
discussion is moisture, where many of the conser-
vation procedures rely on water and at the same
time, water constitutes the base for forming the
paper, for the colour binders and for the adhe-
sives used for mounting paper on the wall. Mr.
McClintock emphasised the risks arisen by mois-
ture introduction, the importance of assessing
objects’ tolerance to water prior to treatment
and the ways in which it can be safely introduced.
Several examples of treatment strategies were
given, from in situ to studio treatments and from
simple pattern papers to complex printed or
refined papers with status of fine art. Again,
balanced solutions for treatment options with
respect to time consuming specific procedures
such as inpainting were discussed.
The conservator’s approach to inpainting is based
on the use of transparent watercolours as these
allow for a gradual effect in value, hue and inten-
sity and because they are rather reversible when
compared to acrylics. Concerning the reconstruc-
tion of loss areas, it is possible as long as another
impression of the same paper is available. The
available reproduction methods for historic wall-
papers and their achieved level of authenticity
and some of the factors that "legitimise" the use
of inpainting in historic wallpapers were also
discussed.
The third lecture, and the most memorable one,
was focused on Globe Conservation.
These works on paper with three-dimensional
format require a challenging and complex con-
servation treatment due to the fact that tech-
9e_conservation
CONFERENCE REVIEW
nically they are made of different materials.
Globes can be distinguished from other works of
art by being objects with decorative purposes
besides being cartographic records and historical
references. For a public less familiar with this
subject, Mr. McClintock made a short summary
of their history, occasion on which he showed a
beautiful collection of images of historic globes.
Globes require a special conservation approach
due to their construction technique which in-
volves other materials in addition to paper. In
their case, the paper covers the surface area of
the three-dimensional object composed of several
elements: core structure, plaster, paper, varnish,
etc. The condition of a globe is mostly influenced
by the state of the plaster sphere, which is nor-
mally affected by moisture, generating cracks
and distortions, and in acute cases, compromising
the state of the fragile layer of paper. Other often
seen problems with globes are varnish and paper
degradation due to abrasion against the horizon
ring and as a reaction to the acidic nature of the
wood, dirt deposits especially on the superior
half of the sphere and varnish discoloration,
among others.
Concerning the treatment of the paper, similar
procedures to those used for other works on paper
are effective, but as the author noted "experience
with a specific type of object teaches that there
is a threshold of treatment, beyond which the
paper should not be subject to additional pro-
cedures to achieve a theoretical, ideal appear-
ance". The treatment is introduced gradually
through the layers, generally starting with sur-
face cleaning and sometimes partial or complete
varnish removal and proceeding to the cleaning
of the paper itself. This was described as a labo-
rious process that can take over one hundred
hours of work, generally under the microscope.
Other complex treatments were also discussed,
such as the removal and treatment of the gores,
lining, filling, remounting and inpainting.
Concerning this last complex operation, it is im-
portant to take into consideration the individual
appearance of the object but also the overall
appearance in relation to the other instances of
the same edition. The rest of the globe elements
are to be treated in rapport with the final appear-
ance of the paper surface. When these elements
are in need of complex procedures, the task is
undertaken by other conservators with relevant
experience.
The last lecture was focused on The Drawings of Frank Lloyd Wright: Observations on their Con-servation. The 20th century well-known architect
produced an impressive number of works (437
constructed projects and around 1000 designs),
major part of his drawings being in storage at
the Frank Lloyd Wright Archives and at Taliesin
West, the architect’s winter home. The collec-
tions gather some 20 000 drawings executed
in "every available medium on a wide variety of
paper and fabric supports with great purpose
and originality". Commonly seen are drawings
on tracing papers executed with graphite and
coloured pencils, drawings in black ink or water-
colour on thicker paper and illustration boards.
In addition to this materials abundance, archi-
tect’s practices such as cutting and pasting
sections of drawings onto other drawings and
assembling several sheets with adhesive tape
make this conservation process even more
complex.
The condition of the collection items greatly
varies and a strategy to draw up a list of priori-
ties in respect to the available resources had to
be developed: drawings with adhesive tape, in-
adequately mounted or in very poor conservation
state that require critical treatment constitute
the highest priority; discoloured, distorted or
very dirty drawings are the next priority and
finally the drawings in stable condition, slightly
distort or with torn edges that require a minor
10 e_conservation
treatment. The drawings were treated in groups
so that projects would maintain a homogeneous
appearance.
The treatment of tracing paper drawings may
represent a challenge, as they are large in size
and depending on how the paper was produced
it can be easily affected by moisture and can
greatly expand parallel to its grain direction.
Methods of addressing problems like poor mounts,
adhesive tape, stains, discoloration and losses
and procedures like stain reduction, filling, lining,
burnishing, flattening and inpainting were dis-
cussed in detail among others. Inpainting is
done with transparent watercolour as the basic
media, sometimes with the addition of pastels
or metallic inks. Su-su, a material obtained from
the brown distillation of boiled paper, is used by
the conservator for inpainting. As mentioned
earlier on, su-su is a very light stable product
and relatively reversible when compared to water-
colour. For the architectural drawings, this ma-
terial was used to tone light areas that could occur
after bleaching, and several other procedures
for areas with losses or that required more ex-
tensive inpainting.
In the end of the lecture, Mr. McClintock over-
viewed his 20 years long experience with this
collection and the way treatment strategies have
changed, acknowledging that the drawings of
Frank Lloyd Wright have taught him "more
about paper conservation than any other single
body of work".
After the lectures, Mr. McClintock answered a
series of questions from a public that was still
keen to learn more about his treatment
strategies.
To conclude, this exhaustive conference was a
memorable experience for us all and we can only
encourage the organiser to continue this sort of
initiatives.
CONFERENCE REVIEW
EITEC 2008the 3rd International Meeting of Technologies Applied to Museology, Conservation and Restoration
23-24 October 2008Porto, Portugal
Organised by:Sistemas do Futuro, Conservar-Inovar, ISQ and DCTP-FLUPhttp://www.sistemasfuturo.com/eitec/
Reviewed by Teodora Poiata
EITEC 2008, the 3rd International Meeting of
Technologies Applied to Museology, Conservation
and Restoration, took place on 23rd and 24th
October 2008. This biannual conference has two
main objectives which are to gather professionals
in the 3 areas previously referred and to disseminate
the latest scientific developments. So far the
conference has been organised in three different
cities of Portugal: Lisbon, Coimbra and now Porto.
11
CONFERENCE REVIEW
This 3rd edition of the conference was a joint
organisation of four Portuguese partners: Siste-
mas do Futuro - Multimédia, Gestão e Arte, Lda.;
Conservar-Inovar, Conservação e Restauro de
Bens Patrimoniais, Lda.; Instituto de Soldadura
e Qualidade (ISQ) and Curso de Especialização
em Museologia do Departamento de Ciências e
Técnicas do Património da Faculdade de Letras
(DCTP-FLUP, University of Porto).
Due to the interest of the overall presentations
and their rich diversity, it was considered more
relevant to describe each presentation instead
of making a critical review of the overall.
The first speaker was Luis Bravo from the Regional
Centre of Porto of the Portuguese Catholic Uni-
versity. In his presentation "Composed digital
images in the study of works of art" he summarised
four main techniques that use the juxtaposition
of digital images to overcome known limitations
of photography. The first technique is the use of
high dynamic range (HDR) images applied to the
digitalisation of wood sculpture x-rays in order to
obtain better results in contrast and resolution.
The second was the use of a strong flash light with
specific filters and the merge of four photos to
obtain a grazing light image in plain daylight.
Next, he presented how by mosaic combination
of several photos a super-resolution image can
be obtained and some other ways to overcome
the light difference among the several photos.
Finally, he explained how the combination of
photos at different depth of field, a technique
called extended depth of field, is able to create
close-up photos without depth of field distortion.
These techniques are very interesting from the
technical point of view, and may also be used for
documentation purposes although how real these
images are is still open to discussion.
Researchers Alberto Proença and João Barbosa
from the University of Minho gave a talk focused
on objects’ digital representation techniques with
PTM (polynomial texture maps): "Affordable
Imaging technologies for Textured Representation
of 3D artefacts". In the same way a grazing light
photograph allows conservators to analyse a
painting’s surface, this technique combines in
one single image light from several points of
origin in order to obtain the best view and read-
ability of a surface. The researchers referred that
the project was developed within an international
team and uses open software allowing an easy
access to the technique. The presentation was
truly educative as several examples were given,
for example, its application proved to be successful
in numismatics to identify some roman coins and
Opening session, Armando Coelho Ferreira da Silva (FLUP), Maria de Fátima Marinho (FLUP), Gonçalo Gonçalves (CMP), Armando Dias and Fernando Cabral (Sistemas Futuro).
Luis Bravo, applying HDR in X-ray digitalisation.
12 e_conservation
CONFERENCE REVIEW
to help to document the pre-historic stone en-
gravings from Côa Valley (Portugal). As these
images are obtained directly without artifices,
this technique could be highly interesting for
documentation purposes.
Pedro Manuel Ramos da Silva, an art historian and
researcher, introduced an often forgotten topic
that is media art, with a presentation entitled
"Media Art. Introduction to conservation and col-
lection of electronic and digital art". The researcher
started by making an historical overview of this
type of art from the beginning of the 20th century
to our days, including installations and video art
and continued with a brief introduction to the prob-
lems that conservation of those media raise, namely
the digitalisation and the archival of digital copies.
The awareness of conservation of these new art
forms must increase and this problematic should
certainly be discussed more in depth.
The presentation "Invisible technology and Muse-
ology excellence" was given by Isidro Moreno, a
professor at the Faculty of Information Sciences
of the Complutense University of Madrid. The re-
searcher reflected on the use of technology in
different museums, from Washington to Tokyo,
and on the physical and conceptual barriers with-
in museums.
Javier Espadas Bardón is the responsible for the
two websites of Fundación Colección Thyssen–
Bornemisza. In the presentation "Museums In-
ternet Visibility Research" he shared the history
of the Thyssen–Bornemisza websites and performed
an in-depth comparison between theirs and other
websites of the most known museums worldwide.
Independently of the collection’s importance
and location, the foundation shows a growing
interest to use the World Wide Web to disseminate
its activities and to turn visitors and internauts
aware of its presence.
Continuing a session almost fully dedicated to
museums and the internet, Pilar Gonzalo spoke
about "Online Community-Building 2.0 for Muse-
ums: Challenges and Opportunities in a Global and
Diverse World". She is a consultant specialised
in digital services for culture and the Executive
Director of the Lamusediffuse Project. The main
question she raised was "Do Museums trust their
users?". Although it is clear that museums don’t,
from "no flash" to "do not touch" signs, the
underlining message of this presentation was the
real need of museums to work with the community.
She also presented a case where only a little effort
and access to the internet were needed to surpass
institutional work. In particular she noticed that
museums in Libya, which is still under dictatorship,
Pedro Manuel Ramos da Silva speaking about Media Art conservation.
Alberto Proença and João Barbosa, revealing almost undetected stone engravings.
13e_conservation
CONFERENCE REVIEW
were not listed in AFRICOM nor easily found on
the internet. Through several contacts and emails
she was finally able to list several interesting
museums that otherwise no one would even know
about except if they would really visit those places.
David Policarpo, representing the private company
Digitrace Portugal, presented a talk focused on
the use of radio-frequency identification (RFID)
to mark and to trace stolen works of art. During
his presentation he overviewed other marking
methods as well and noted that the digitrace
system was first applied by Vincent Peyronnet to
works of art. The fact that many stolen works of
art are retrieved by authorities but their prove-
nance remains unknown or their owners do not
provide sufficient ownership proofs was also noted.
José Manuel Gaspar Nero, from Instituto Superior
Técnico, approached the rehabilitation of urban
built heritage. His presentation summarized his
personal reflection on the actual problematic of
urban rehabilitation in Portugal. He mentioned
not only the recent rehabilitation of historic
buildings, such as Lisbon’s Castle among other
monuments, but also the present and future re-
habilitation of today’s constructions. Indeed, the
change of paradigms and the actual trends lead
to a lack of sustainability. This is a required dis-
cussion in today’s chaotic city.
João Carlos Santos, architect at IGESPAR, the Por-
tuguese public institute responsible for architec-
tonic heritage, summarized the 20 years rehabili-
tation process of the 11th century monastery of
São Martinho de Tibães, in northern Portugal.
Sold to the private sector after the nationalisation
of the Church property in the late 19th century,
the monastery was bought by the Portuguese
State in 1986. After a century of low maintenance
and even a fire incident, the monastery is being
requalified at the moment so it can be occupied
again by a monastic order who will provide services
to the community to help its maintenance.
Closing the last session of the first day, Jose Antonio
Teran Bonilla, architect from the Faculty of Archi-
tecture of the National Autonomous University of
Mexico, spoke about a local rehabilitation project
of the 17th and 18th century neighbourhood of San
José, the historical centre of Ciudad de Puebla.
The first speaker of the second day was António
Portugal from the Faculty of Sciences and Tech-
nology, University of Coimbra. His presentation
was dedicated to the study of fungi on historical
documents from the archive of University of Coimbra.
The project focused on the identification of fungi
through DNA study and the implementation of
treatment methods based on gamma radiation.
Pilar Gonzalo, "Do museums trust their users?"
João Carlos Santos, presenting the rehabilitation of the monastery of São Martinho de Tibães.
Luísa Botelho, from the Technological and Nuclear
Institute (ITN) and ITN’s spin-off CHIP, presented
hygienisation procedures by the use of gamma
rays in ITN’s facilities. Gamma radiation interferes
with the genetic material of cells and it is being
used to kill insects and microorganisms in several
applications. Some examples were given concerning
the use of this method in conservation for wood
sculptures hygienisation. The subject of long term
effects was raised but further research is still
required.
One of the most interesting presentations was
given by Hans-Christoph von Imhoff, a paintings
conservator-restorer and coordinator at ICOM-CC,
who presented "Conservator-restorers of material
cultural heritage - Aspects and development of
their profession since WW II". Mr. von Imhoff sum-
marised the history of the conservator profession,
with a special focus in the creation of major Euro-
pean institutions and the international ethics
charts. Speaking about education in our profession,
he mentioned that while some European country's
universities tend to merge successfully the theo-
retical with practical knowledge, others still tend
to overestimate the value of the theory. He ob-
served a lack of balance between "brain and hands"
in plenty of universities that offer conservation
degrees. Thus, there are many conservation gradu-
ates that know how to prepare "very good thesis"
but in fact they have lack of experience and limited
manual skills. This serious problem requires uni-
versities’ concerted efforts in order to offer a
solution without delay.
A project involving the conservation treatments
of historic lead seals appended to parchments
from the Archive of the University of Coimbra was
presented by Catarina Isabel Santos, a chemist
from the Department of Chemistry from the Uni-
versity of Coimbra. Their collection includes several
seals from diverse centuries presenting different
alteration states that are not directly related to
their natural ageing. As the main problem of the
seals is related to the transformation of lead into
lead salts, the project aims to characterise the
source material through non-destructive analysis
by XRF. The project included the reconversion of
the lead salts into lead through local electrolytic
reduction while the natural fibbers were protected
with cyclododecane. The archival conditions were
also changed in order to better preserve the lead
seals. Although this project uses already estab-
lished techniques, it is a new treatment in Portugal.
The next intervention was performed by Rui
Bordalo from Instituto de Soldadura e Qualidade
(Portugal) who introduced to the public the effects
that ultraviolet laser radiation induces in pigments,
with a focus on the analytical characterisation of
the alterations. Irradiated and non-irradiated
pigment samples were analysed by several tech-
niques, among which infrared and Raman spectros-
copy, SEM-EDX and colorimetry. Although the
effect of laser radiation in pigments is a broad
area and several studies have already approached
this subject, this study is far more comprehensive
than others. The samples were produced in order
Paula Menino Homem, Maria Luísa Botelho, Hans-Christoph von Imhoff, António Portugal and Catarina Isabel Santos. Discussion panel after the morning session of the second day.
14 e_conservation
CONFERENCE REVIEW
to reflect those of a real painting, including
pigments mixtures and artificial aging equivalent
to several decades of exposure in museums condi-
tions. The chemical and physical changes induced
by the 248 nm laser to pigments and linseed oil
were discussed.
Carlos Suárez from the private company ECOMOR
presented the advantages that cryogenic cleaning
has on stone and metals. The cryogenic cleaning
is based on the ejection of solid CO2 with compressed
air. It was a rather interesting presentation as it
included several video demonstrations of its clean-
ing power and other advantages were discussed.
However, data of possible disadvantages in the
removal of selected layers in cultural heritage
artefacts and its impact on long term was not
available.
Piero Baglioni, from the Department of Chemistry
and CSGI of the University of Florence is a key
player in the conservation field. His outstanding
presentation was entitled "From micelles to micro-
emulsions, gels and responsive nanomagnetic gels:
when hard and soft matter merge together". Dr.
Baglioni’s procedure of cleaning works of art using
nanomagnetic sponges was last year’s news after
its testing in the laboratory proved successful.
The technique was described as being based on
nanoparticles made of cobalt and iron oxide which
are mixed into a polymer gel, creating a magnetic
sponge. Its application was demonstrated by a
fascinating video showing a very simple process
of coating a surface with a few drops of gel and
its further removal by a magnet, after it had dis-
solved the dirt from the surface. The author also
presented a summary of his 2 decades experience
and research dealing with nanomaterials and
their application to cultural heritage. Images
from the conservation treatments applied by
him and his team on mural paintings ensembles
in Italy and Mexico have showed that this tech-
nology is indeed a real advance in the field of
conservation, due to the outstanding recovery
of the paintings from their advance state of decay.
The conference's last speaker was Cristina Nabais
from the Centre for Functional Ecology from the
University of Coimbra. This biologist presented
some results from a project that aimed to study
the wood species from sculptures belonging to
the collections of the National Museum of Ancient
Art (Lisbon) and from the Grão Vasco Museum
(Viseu). The project aimed to identify and later
to correlate wood species according to their prove-
nance and attribution with the history of the
forest and the historic wood commerce. In spite
of the obvious relevance of this study for the two
reference collections that it was performed for,
I believe such a project should be continued and
extended to include more elements in order to
widen its representativity.
The event was well planned, the EITEC organisers
giving attention to each detail and taking advan-
tage of the historic city of Porto that is worth to
be visited. The warm atmosphere and the comfort-
able scientific and social environment made this
conference a very pleasent experience. We look
forward to attending the next EITEC edition.
Piero Baglioni, speaking about the use of nanomaterials in conservation of works of art.
15e_conservation
CONFERENCE REVIEW
The News section is publishing the most diverse
information on cultural heritage topics, such as
on-site conservation projects reports,
conferences, lectures, talks or workshops
reviews, but also course reviews and any other
kind of appropriate announcements. If you are
involved in interesting projects and you want to
share your experience with everybody else,
please send us your news or announcements.
For more details, such as deadlines and
publication guidelines, please visit
www.e-conservationline.com
The Getty Conservation Institute (GCI) is a well-
known institution devoted to the development
of visual arts conservation. Recently, the institute
launched the GCI Bulletin, a free bimonthly e-
bulletin. As announced, "It will complement the
GCI's print newsletter, Conservation. Published
six times a year, the GCI Bulletin offers updates
on our events, science and field projects, educa-
tional initiatives, and publications and videos".
The first and current issue can be consulted at
http://www.getty.edu/conservation/publications/
bulletin/current.html.
The bulletin is divided into two main areas. The
"projects and activities" section contains infor-
mation concerning GCI related events. Among
other events, this first issue highlights a forth-
coming roundtable forum on Managing Urbani-
zation and Conservation in Cambodia and a
symposium on Panel Paintings to take place in
2009 at the Getty Center. The "publications,
videos, and audio" section presents information
related to media news. The first issue contains
announcements such as the publication of the
book The Craftsman Revealed: Adrien de Vries,
Sculptor in Bronze which is the technical study
of twenty-five bronze sculptures, the latest
issue of Conservation and the GCI newsletter.
You can also read about the most recent acqui-
sition of GCI’s Research Library and watch a
seven-minute video on Asian organic colorants.
If you wish to subscribe the GCI Bulletin please
visit http://www.getty.edu/subscribe/
gci_bulletin/index.html.
GCI BULLETIN
The Getty Conservation Institute
NEWS
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even
ts
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Sharing Conservation Decisions.2008
Lessons in Anatomy Made Easy
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Permanence in Contemporary Art: Checking Reality
Date: 3-4 November Read more...
Place: Copenhagen, Denmark
The seminar, which will encourage interdisciplinary
exchange between museum professionals including
conservators, art historians, artists and others,
will take place in conjunction with Reality Check,
an exhibition at Statens Museum for Kunst,
opening fall 2008. Reality Check will act as a
thematic springboard for the seminar, addressing
issues related to content, material, time,
exhibition and context exemplified by works in
the exhibition.
Responsibilities and Opportunities in Architectural Conservation
Date: 3-6 November Read more...
Place: Amman, Jordan
Architecture and heritage are intertwined through
conservation. Architecture is a container of
heritage in the sense that anything related to
history and culture had occurred in space and in
a place, the raison d’être of architecture. A guiding
hand in human endeavors, heritage is a record
of cultural precedents in any society, and as such,
it is a foundation for growth and advancement
in any human discipline, profession, or industry.
Cultural Heritage Research Meets Practice
8th European Conference on Research for Protection, Conservation and Enhancement of Cultural Heritage
Date: 11-12 November Read more...
Place: Ljubljana, Slovenia
The main objective of the conference is to foster the
exploitation and spin off of EU research results. New
technologies, tools and devices will be presented through
talks, posters, exhibitions and practical workshops.
The events in this section are linked
to the original homepage of the
organisers. In case the event does not
have an individual page, the calendar
of events will open at
www.conservationevents.com.
Click on "Read more..." to find out
more details about each event.
International Course
Date: 3-28 November Read more...
Place: Rome, Italy
The purpose of the course is to improve conservation
decisions by involving the various professions and
stakeholders, and ensuring transparency, clarity, and
the effectiveness of the process. It is designed for any
professional actively involved in heritage conservation.
Anatomical models in scientific and cultural context
Date: 6-7 November Read more...
Place: Leiden, The Netherlands
Museum Boerhaave organises on 6-7 November 2008 an
international conference on anatomical models in their
scientific and cultural context. The occasion for this
conference is the completion of the restoration of the
papier-mache anatomical models of Dr. Louis Thomas
Jerome Auzoux, one of the largest collections of this
kind in the world.
e_conservation
EAS - Eastern Analytical Symposium
Date: 20-22 November Read more...
Place: Castellón, Spain
En esta decimoséptima edición las sesiones de trabajo
de los 11 Grupos Científicos siguen siendo inauguradas
por profesionales de relevante prestigio internacional,
mediante una conferencia que versa sobre los últimos
avances científico-tecnológicos en el campo de la
conservación y restauración de Patrimonio.
La conferencia contará con la presencia de René Larsen,
de ENCoRe, y Jan Wouters del IRPA entre otros.
17th International Meeting on Heritage Conservation
Date: 17-20 November Read more...
Place: New Jersey, USA
The Eastern Analytical Symposium and Exposition is held
each year to provide professional scientists and students
continuing education in the analytical and allied sciences
through the presentation of symposia of papers, workshops,
and short courses. In addition, an exposition of apparatus
and supplies allied to these sciences is held concurrent
with the symposia.
Youths in the Conservation of Cultural Heritage - YOCOCU
First International Meeting
Date: 24-25 November Read more...
Place: Rome, Italy
Addressed mainly to young Architect, Conservation
Scientist, Art Historians Conservator/Curators,
Conservator/Restorer and others, consists of a two
days conference: the first devoted to the policy and
strategy to promote an active role of these actors in the
conservation field, white the second, to give voice to
young professionals to share experiences, studies and
new researches.
II International Congress of Experimental Archaeology
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Museums and DisastersICOM / ICMAH Annual Conference 2008
Date: 12-16 November Read more...
Place: New Orleans, USA
This conference will explore the various ways in which
museums document and interpret the direct and indirect
effects on society of natural, economic, and military dis-
asters. It will be held in a city that suffered a devastating
flood in 2005 that killed 1,464 people and where recovery
has been painfully slow. Special emphasis at the conference
will be on recent history/contemporary events.
VAST2008 - International Symposium on Virtual Reality, Archaeology and Cultural Heritage
Date: 2-6 December Read more...
Place: Braga, Portugal
VAST2008 continues the tradition of excellence in the VAST
symposia for technologies in service of cultural heritage.
This year's symposium emphasizes the ephemeral nature
of the subject of our disciplines, namely the tangible/
intangible cultural heritage artifacts - archaeological
remains, buildings, manuscripts, etc. - and the new virtual
heritage artifacts we are producing in order to document,
analyze, visualize and share our pasts through digital means.
Date: 26-28 November Read more...
Place: Ronda (Málaga), Spain
The second International Congress of Experimental
Archeology is being held to meet two general aims:
to set out the recent theoretical-methodological
contributions in the field of experimental archaeology
and, in the second place, to provide a place for
archaeological researchers to meet and debate.
EVENTS
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Material Worlds
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Se coordonner en cas de sinistre : métiers, tutelles, réseaux
Comité français du Bouclier Bleu - Journées d'études
Date: 4-5 December Read more...
Place: Paris, France
Le Comité français du Bouclier Bleu s’est donné pour mission
l’information, la réflexion, l’échange des connaissances
et des méthodologies auprès de l’ensemble des personnes
pouvant être concernées, au titre de leur responsabilité
professionnelle ou citoyenne, par une action face aux
risques majeurs encourus par les biens patrimoniaux.
Measuring the Value of material Cultural Heritage
Second HERITY International Conference
Date: 3-5 December Read more...
Place: Rome, Italy
The Conference is aimed to make possible to exchange
ideas and experiences at an international level on the
aims, possibility to measure, and the ways to describe
the concept of Value related to material Cultural
Heritage open to the public (Monuments, Museums,
Archaeological sites, Libraries and Archives) from
different points of view;
The Sixth International Conference on Science and Technology in Archaeology and Conservation
Date: 8-14 December Read more...
Place: Rome, Italy
The main theme of the 2008 conference will be
Documentation and Risk Management of the Cultural
Heritage (CH). While documentation has long been
recognised as an important tool for Cultural Resource
Management and the Conservation and Preservation of
CH sites and artefacts, it is gaining more and more
importance in Risk Management.
Pest Management in Practice
Date: 10 December Read more...
Place: Glasgow, Scotland, UK
The event comes in continuation of the previous
pioneering conference "2001 - A pest odyssey" held
at the British Library. In this new meeting, in Glasgow
in 2008, we hope to build on the success of the first
workshop and introduce new IPM topics from the
northern part of the UK. One of the most important
tasks of this workshop will be to enable people to share
and discuss their problems and successes and then to
formulate a set of guidelines and priorities for future
work and research to make IPM even more effective.
Dece
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Date: 15-17 December Read more...
Place: Leicester, UK
A conference in honour of Professor Susan Pearce
University of Leicester
Professor Susan Pearce is an internationally renowned
professor of museum studies and historical archaeologist,
who has had a long and important association with
material culture studies both within and beyond the
museum. The conference is focused on Professor Pearce's
contribution to the field with a significant material
culture studies conference and the subsequent publica-
tion of a volume of essays based on the conference
papers. Both the conference and the volume will
explore agenda in theoretically-oriented material
culture studies. We are now inviting the submission
of abstracts. Presentations will address or inform
approaches to theorising relationships between people
and the material world. The range of potential themes
is broad, and might include embodied experience and
sensory engagements, the agency of – and distinctions
between – objects and persons, the construction of
value, etc.
EVENTS
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arti
cles
AREAS OF PUBLISHING
Conservation TreatmentMural Painting
Painting
Stone
Sculpture
Textiles
Paper / Documents
Photography
Metals
Tile / Ceramic / Glass
Furniture
Music instruments
Ethnographic assets
Archeological objects
Conservation ScienceScientific research
Material studies and characterisation
Analytical techniques
Technology development
Biodeterioration
State-of-the-art
Reviews
Preventive ConservationTheoretic principles
Case studies
Documentation in ConservationStandardisation
Documentation methods
Data management
Conservation TheoryEthics
Conservation History
Art History, Iconography,
Iconology, Chemistry, Physics,
Biology, Photography, Cultural
Management, Museology,
Computer Science, Legislation
and Juridical Processes,
Conservation Policies
and any other field applied to
Conservation and Restoration
of works of art.
Find out more: www.e-conservationline.com
e_conservation
THE VISIBLE IMAGEIS NOT ALWAYS CORRECT
The differentiation of layers by optical microscopy in samples’ cross sections
by Carolina Barata, António João Cruz and Marta Ferro
The stratigraphic characterization of polychrome surfaces in works of art is frequently
done through the observation of cross-section samples by optical microscopy (OM).
Three examples that show some limits to this method are presented here. In samples
where at first only one layer was visible, several strata were detected through electron
microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). These and other
examples ought to be taken into consideration by conservators, who should be aware
of similar possibilities in other cases.
At least since the middle of the 19th century,
minute samples collected from works of art were
mounted in resins, cut, polished and observed
using optical microscopes [1]. However, only
during the first half of the 20th century has this
method been developed and employed more fre-
quently [2,3]. Through the optical microscopy (OM)
of cross sections from works such as paintings
and polychrome sculptures, usually under a mag-
nification of 100x to 300x, it is possible to deter-
mine the number and sequence of layers and to
characterize each one of them with respect to
matrix heterogeneity, particle size, color, shape
and transparency, among other aspects.
The information obtained is useful, for instance,
for the characterization of artist techniques, the
distinction between original materials and over-
paintings, and the diagnosis of the conservation
condition. As it is known by any conservator, many
examples are found in countless publications con-
cerning the materials of paintings and sculptures.
Today, with the same goal in mind, the embedded
cross sections are also analyzed through some
advanced analytical methods, namely scanning
electron microscopy (SEM), Fourier transform
infrared spectroscopy (FTIR) and mass spectrometry
[3]. However, despite the extra information pro-
vided by these methods, particularly in what con-
cerns the chemical composition, the examination
of cross sections by conservators is usually limited
to OM. The situation can be explained by a number
of reasons such as the relative low cost of the
equipment that is required, and to the fact that
the information obtained in many cases is both
easily interpreted and sufficient.
In some situations, however, the images acquired
by OM can lead to false conclusions. These situ-
ations are probably not that frequent, but it is
important for conservators to be aware of this
possibility, especially when false conclusions may
have significant consequences.
The observation of only one stratum by OM when
several strata are in fact present, is probably the
most common situation.
In the context of a Masters dissertation that
aimed to contribute to the characterization of
the Portuguese polychrome wooden sculpture
from the Baroque period [4], the observation of
cross sections, both by OM and SEM with energy
dispersive X-ray spectroscopy (SEM-EDS), led to
the detection of some interesting cases. For OM,
an Olympus binocular microscope, model BX41,
equipped with an Olympus Digital C-4040 Zoom
camera with infinity corrected optical system,
was used. The analysis by SEM-EDS was done in
Hitachi SU-70 UHR Schottky FE-SEM with samples
coated with carbon. In some samples, according
to OM, the ground layer was composed of one
stratum. However, through SEM-EDS, particularly
through the maps of elements obtained, it was
determined that the ground was actually composed
of several strata, as showed by the chemical dif-
ferences or the limits that were detected between
them. In that study, the conclusions about the
real number of strata were important, since one
of the aspects under research was the relation
between the information found in art treatises
and working contracts, according to which the
ground should be composed of several strata,
and the workshops’ practice.
One example is the cross section taken from the
blue vestment of a sculpture representing Saint
Andrew, dating from the second half of the 18th
century, and part of the collection of the museum
of Santa Maria de Lamas (Figure 1). Although a
certain heterogeneity in the ground layer was
visible, it was not possible to subdivide it. How-
ever, as revealed by SEM-EDS it was composed
of a first stratum, enriched in calcium and lead
22 e_conservation
CAROLINA BARATA, ANTÓNIO JOÃO CRUZ & MARTA FERRO
1 32 4
(Figures 2-3) (probably a mixture of gypsum and
white lead), a second stratum, enriched in alu-
minum (Figure 4) and silicon (probably a mixture
of clay minerals and other silicon compounds),
and a third stratum, also enriched in aluminum
and silicon but with a high content of lead
(probably a mixture of the same compounds
present in the second stratum with white lead).
Another example is provided by the sample taken
from the flesh area of a sculpture representing
Saint Francis Xavier (Figure 5), which dates from
the last quarter of the 17th century and belongs
to the same collection. The brownish color on the
top of the ground layer was first interpreted as
being a result of the impregnation of that layer
by glue. This interpretation was also supported
by the fact that no significant differences in the
particles’ size and shape were detected inside
the ground. The maps of elements obtained by
SEM-EDS, however, showed that this was not
correct. Instead, they revealed that the ground
is composed of a stratum enriched in calcium and
lead (probably white lead mixed with a calcium
filler) at the base (Figures 6-7), followed by a
stratum mainly composed of clay minerals,
revealed by its high contents of aluminum
(Figure 8) and silicon.
23e_conservation
Figure 1. OM - cross section taken from the blue vestment of Saint Andrew (100x).At the top, layers identified by OM: 1 – ground; 2 – bole; 3 – gold leaf; 4 – paint layer. At the bottom, 1a, 1b and 1c corre-spond to three different strata with different composition identified by SEM-EDS in the ground layer.
Figure 2. SEM-EDS – map of Ca of the cross section observed in figure 1.Figure 3. SEM-EDS – map of Pb of the cross section observed in figure 1.Figure 4. SEM-EDS – map of Al of the cross section observed in figure 1.
DIFFERENTIATION OF LAYERS IN CROSS SECTIONS
We must point out that, in principle, cases like
these can also be detected by other methods.
Ultraviolet microscopy, which involves the obser-
vation of a sample exposed to ultraviolet radiation
through an optical microscope, is such an example
[3, 6]. Its usefulness is particularly expected when
a highly fluorescent material shows different con-
centrations in different layers. Stain tests directly
applied on cross sections are also an accessible
alternative to SEM-EDS [6]. In this case different
materials should react in different ways to a
specific reagent.
As a conclusion, the main point that we would like
to emphasize is that one should bear in mind that
The last example comes from a sculpture from the
second half of the 18th century representing Saint
Dominic, also belonging to the collection of the
museum of Santa Maria de Lamas [5]. In the sample
taken from the black vestment, a reddish layer of
bole seems to be present between the layer of gold
leaf and the ground, although the separation
between the bole and the ground was not clear
(Figure 9). The ground layer seems to be uniform,
but the combined map of several elements, obtained
by SEM-EDS, suggests that it may be composed of
at least three strata, as some lines are observed
that probably corresponds to theirs limits (Figure
10). Additionally, the extension of the bole layer
in this map is clearly delimited.
24 e_conservation
1 32 4
Figure 5. OM - cross section taken from the flesh tone of Saint Francis Xavier (100x). At the top, layers identified by OM: 1 – ground; 2 – lead white; 3 – paint layer; 4 - overpainting. At the bottom, two different strata identified by SEM-EDS in the ground layer: 1a – mixture of calcium filler and white lead; 1b – clay minerals, first interpreted as animal glue.
Figure 6. SEM-EDS – map of Ca of the cross section observed in figure 5 (300x).Figure 7. SEM-EDS – map of Pb of the cross section observed in figure 5 (300x).Figure 8. SEM-EDS – map of Al of the cross section observed in figure 5 (300x).
CAROLINA BARATA, ANTÓNIO JOÃO CRUZ & MARTA FERRO
25e_conservation
when only one layer is detected by OM, in some
cases several other layers might be present and
be detectable by other methods. Although several
examples of this have already been published, we
none the less think that it is important to draw
attention to this fact in a clear and explicit way.
Figure 9. OM - cross section taken from the black vestment of Saint Dominic (100x). At the top, layers identified by OM: 1 – ground; 2 – bole; 3 – gold leaf; 4 – paint layer. At the bottom, 1a, 1b and 1c correspond to the three different strata identified by SEM-EDS in the ground layer.Figure 10. SEM-EDS - map of elements of the cross section observed in figure 9.
References
1. J. Nadolny, "The first century of published scientific
analyses of the materials of historical painting and poly-
chromy, circa 1780-1880", Reviews in Conservation, 4
(2003) pp. 39-51.
2. J. Plesters, "Cross-sections and chemical analysis of
paint samples", Studies in Conservation, 2 (3), (1956)
pp. 110-157.
3. N. Khandekar, "Preparation of cross-sections from easel
paintings", Reviews in Conservation, 4 (2003) pp. 52-64.
4. C. Barata, "Caracterização de Materiais e de Técnicas de
Policromia da Escultura Portuguesa sobre Madeira de
Produção Popular e de Produção Erudita da Época Barroca",
MSc dissertation, Faculdade de Ciências da Universidade
de Lisboa (2008).
5. C. Barata, A. J. Cruz, J. Carballo and M. E. Araújo, "Os
materiais e as técnicas usados numa escultura barroca,
do Museu de Santa Maria de Lamas, representando São
Domingos", Conservar Património, 6 (2007), pp.21-30.
6. M. Matteini and A. Moles, Ciencia y Restauración. Método
de investigación, Editorial Nerea - Junta de Andalucía,
Guipúzcoa - Sevilla (2001).
CAROLINA BARATAContact: [email protected]
Carolina Barata, sculpture conservator, owns a
bachelor's degree in Conservation and Restoration
and a master's degree in Chemistry Applied to Cul-
tural Heritage. Presently she is a lecturer at the
School of Arts of the Portuguese Catholic University.
ANTÓNIO JOÃO CRUZContact: [email protected]
António João Cruz, conservation scientist, received
his Ph.D. in Analytical Chemistry from the Faculty
of Sciences of the University of Lisbon. At the
moment he teaches at the Polytechnic Institute
of Tomar.
MARTA FERRO Contact: [email protected]
Marta Ferro, specialist in electron microscopy, is
currently working at the University of Aveiro and
at the Centre for Research in Ceramics and Com-
posite Materials (CICECO).
DIFFERENTIATION OF LAYERS IN CROSS SECTIONS
by Ioan Istudor
THE CHURCH OF VORONET MONASTERYTechnical considerations of the mural paintings
,
The church of Voronet Monastery is one of the
many medieval monuments from Bukovina - a
historical region located in northeast Romania –
that was built in 1488 by Prince Stephen the
Great in only three months and three weeks, ac-
cording to the commemorative inscription of the
church. The church was built on a triconch plan
with altar, naos and narthex and was painted in
the same period. Later in 1547, the Metropolitan
Bishop of Moldavia, Grigorie Rosca, added an
exonarthex to the west end of the church and
decorated it with mural paintings, together with
all the facades.
Although the number of churches from Bukovina
with exterior mural paintings painted in the same
period is large, many of them are only partially
preserved. Among the most remarkable ones are
the mural ensembles from Humor (1535), Moldo-
vita (1537), Arbore (1541), Voronet (1547) and
the most recent, Sucevita (1601).
The mural paintings from Bukovinean churches,
particularly those with exterior mural paintings,
have always produced a strong impression on those
who have admired them. Their colours, brilliantly
preserved after so many centuries, appear as a
phenomenon and represent an exception due to
their execution technique. Specialists were always
impressed by the exceptional intensity of their
colours, moreover since these monuments are
located in a very harsh environment.
To answer the many questions asked about the
materials and techniques used in the execution
of the exterior murals of churches from Bukovina,
a series of technical research projects were started.
The first studies started in 1963 at Voronet when
samples from mortars, pigments and binders were
analyzed by micro-chemical and chromatographic
methods1 [1] and subsequently, in collaboration
Image 1. The church of Voronet Monastery.
1 Chromatographic analyses were performed according to Margaret Hey [1].
THE CHURCH OF VORONET MONASTERY
27e_conservation
28 e_conservation
with other institutions2, through mineralogical
analysis, spectroscopy and IR spectrometry. The
first results on the controversial blue pigment and
its alteration on the south facade - in the areas
affected by moisture - were published in 1965
[2]. Until that date, there was no precise infor-
mation supported by scientific research, but only
speculations which have not been confirmed by
subsequent studies3.
The technological examination of the interior and
exterior mural paintings from Voronet church
focused on the technical and material elements
that could explain the unusually good conserva-
tion state of the painting. The quality of materials
used by the artists and the correct execution tech-
nique led to the completion of a painting that draws
attention not only due to its artistic remarkable
qualities but also due to its exceptional execution
technique.
Research results
The interior painting was executed according to
the Byzantine technique, on a fresco plaster
(intonaco) consisting of lime mortar with hemp
tow, which was applied over another layer of plaster
made of lime mortar with straw and chaff (arriccio),
that had the purpose of making the wall surface
even. The same traditional Byzantine technique
can be seen at St. Sofia from Trebizonda (13th
century) and Kariya Çamii (Chora) from Istanbul
(1320). The same procedure was used at Voronet
in the execution of the exterior painting made
during Prince Stephen reign, such as the register
with geometric motifs above the wall bench of the
south facade (Images 2, 3). Traces of painting from
the west facade of Prince Stephen’s church are still
preserved in the porch’s attic and on the eastern
wall – the inferior curtain decorated register.
According to a fresco painting technique, the into-
naco was applied in horizontal registers separated
in pontate4 and giornate5 whose horizontal and
vertical joint traces are visible in several places
(Image 4) and constitute an undoubted proof of
IOAN ISTUDOR
Images 2 and 3. South facade. Decorative geometric motif located above the wall bench (painting from 1488).
2 Mineralogical and spectroscopic analyses were conducted in 1963 by the university lecturer Dr. Dumitru Sandu and his collaborators from the Mineralogical Laboratory of the Uni-versity of Bucharest and at National Research & Development Institute for Chemistry and Petrochemistry (ICECHIM) (analysis certificate No. 317 / 09.05.1966).
3 For subsequent research I benefited from the collaboration of the architect and painter Ion Bals, whose knowledge in painting techniques was a real help in the interpretation of the chemical analyses results.
4 Pontata (Italian ponte = scaffold) is a term that defines an area of wall painting executed in fresco, which usually cor-responds to a scaffold floor, being delimited by horizontal plaster joints.
5 Giornata (Italian giornata = a day) is a term that defines a wall painting area painted a fresco "in a day". The horizontal succession of giornate distinguished by vertical joints consti-tute a pontata.
29e_conservation
a fresco execution.
The colours were applied after the intonaco layer
was well compacted and the design was marked by
incisions. Traces of these preliminary operations
(trowel traces and incision) can be observed on
the surface of the plaster in grazing light6 (Images
5-8). The durability of Byzantine frescoes is mainly
due to the procedure of compacting the plaster
previous to the colour application.
6 In Byzantine technique, the compacting of plasters had the
purpose of breaking the superficial crust of calcium carbonate that
forms on intonaco, bringing to the surface the calcium hydroxide
solution for a good pigment carbonatation. This provides the gloss
and depth of tones but also a greater resistance of the fresco painting.
Image 4. Narthex, north wall. Decorative ornament painted on a 'pontata' joint.
Images 5, 6. Narthex, north wall. Photos in direct light (left) and grazing light (right). Traces of compacted plaster and drawing incision.
THE CHURCH OF VORONET MONASTERY
30 e_conservation
Image 7. Narthex, south wall. Photo in grazing light showing the relief of the surface.
Image 8. Details regarding the execution technique.
IOAN ISTUDOR
31e_conservation
Colours were obtained by mixing pigments with
water, lime water or lime milk in order to obtain
more transparent or matte layers. Pigments used
are shown in Table 1.
Except the black pigment obtained from charcoal,
all the other pigments used are mineral substances,
natural or synthetic: coloured earth with iron
oxide hydrate (ochre), or anhydrous (red ochre),
Fe, Al, Mg and K (green earth) hydrosilicate, red
lead oxide (minium), copper minerals (azurite
and malachite)7 [3], mercury sulphide (cinna-
bar), silicates (smalt)8 and calcium carbonate9
(white).
Cinnabar pigment was greatly used in the altar,
naos and narthex, for both the garments and
decorations – curtains and red strips. In the
painting of the exonarthex (added in 1547), pre-
dominant is the use of minium (red lead). Minium
(Pb3O4) suffered here, as everywhere else where
it was used in wall paintings (frescoes and tem-
peras), a microbiological alteration transforming
into lead dioxide (PbO2) of dark brown colour [4]
(Image 9).
Red ochre pigment was greatly used in all church
compartments and is the only red pigment used
in the exterior painting.
No. Location
ochr
e
Wall preparation(mortar composition
for intonaco and arriccio plasters)
1 Altar + + + + + + + + + Arriccio: lime, straw, chaff;Intonaco: lime, tow, 3-6 mm
2 Naos + + + + + + + + arriccio lime, straw, chaff;Intonaco:lime, tow, 10-15 mm
3 Narthex + + + + + + + + Arriccio: lime, straw, chaff;Intonaco: lime, tow
4 Exonarthex + + + + + + + + Arriccio: lime, straw, chaff;Intonaco: lime, tow
5 Exterior (1488)
+ + + + + Arriccio: lime, straw, chaff;Intonaco: lime, tow
6 Exterior (1547)
+ + + + + + + + + Intonaco 3-13 mm, lime mortar, sand and brick dust, 32-62%
red
ochr
e
cinn
abar
min
ium
(re
d le
ad)
azur
ite
smal
t
gree
n ea
rth
mal
achi
te
lime
whi
te
char
coal
bla
ck
gold
7 Azurite is a natural mineral substance, basic copper carbonate [2CuCO3
.Cu(OH)2] which is found in secondary deposits of copper minerals, associated with malachite, which is also a basic copper carbonate [CuCO3
.Cu(OH)2] [3].
8 Smalt pigment is a synthetic silicate, a potassium glass coloured with cobalt minerals that has been produced in various workshops according to local recipes, having in consequence different durability and various colours, more or less intense. Its colour varies according to its cobalt
content. The smalt used at Voronet is slightly coloured and has a refractive index between 1.535 and 1.540. Smalt particles size range from 0,05 µm to 0,19 µm.
9 It has been determined by chemical analysis that the white pigment is calcium carbonate. According to the handbooks, this could be obtained from rich lime dried in the sun, or from recovered old fresco plaster, in dust. Rich lime whitens the colours with which it is mixed thus its mixture with other pigments was avoided, being only used as pure white.
Table 1. Pigments and plaster mortars.
THE CHURCH OF VORONET MONASTERY
32 e_conservation
Regarding the blue surfaces (the famous 'Voronet
blue'), they were executed with azurite pigment
(basic copper-carbonate) on black background
consisting of charcoal for two reasons: optical
properties (to enhance the colour intensity) and
isolation10 against the excessive lime alkalinity
(Images 10 and 11).
In the interior painting from Voronet, a mixture
between azurite and smalt pigments was also
used (Image 12 and 13).
In the steeple, the quantity of smalt used varies,
being predominant especially on the registers de-
picting cherubim, seraphs, prophets and liturgical
angels. On the walls of all church compartments
it can be observed that the amount of smalt mixed
with azurite is very small. The presence of smalt
in azurite does not appear to be accidental as a
similar case was noted by the Italian researcher
Paolo Benzi [5], quoting Dell Serra. Studying the
work of Sodoma painter for the Monte Oliveto
Magiore monastery (1505 - 1508), he considers
that it does not correspond to the "canonical"Image 9. Exonarthex vault. The alteration of minium(red lead) into dark brown lead dioxide.
10 The layer of black (charcoal) has a thickness between 30 and 60 µm (measures performed in the non-degraded areas). Azurite particles size varies between 10 and 30 µm. The actual thickness of the colour layer of the interior painting varies between 30 and 50µm (and reaches over 100µm in the exterior painting, in the superior registers which are more protected by eaves).
Image 10 (left). Stratigraphic section from "Tree of Jesse" scene. The azurite blue pigment applied over the black
charcoal background can be seen.Image 11 (right). Azurite pigment, OM photography.
IOAN ISTUDOR
33e_conservation
a fresco technique and notes that "azurite, mixed
with smalt was probably applied a fresco on an
intonaco not completely dry (quasi completamente
secco), perhaps with the addition of an organic
binder" [5]. Traces of smalt in azurite are also pre-
sent in the exterior painting from Voronet and
Moldovita. It is possible that the initial amount
of smalt has been higher, but its compatibility
with the binder is smaller than that of azurite and
thus it was mostly lost under climatic influences.
The green colour was obtained from malachite or
green earth pigments. Malachite was used in the
exterior and in the porch, while the earth green
has been used very much in the interior as well
as exterior painting. Again, its preponderant use
for certain areas can be noticed: backgrounds,
garments and floral decorative motifs, and its
application was done mainly over a charcoal black
background but also pure or mixed with charcoal
black. The earth green used on the south facade
1488 exterior painting, register depicting geo-
metric decorative motifs, shows a yellowish-
green11 [6] shade due to the influence of the
capillarity humidity. This shade may belong to
the original pigment colour or could have appeared
as result of a partial alteration.
Image 12. OM photography, smalt pigment structure.
Image 13. Naos steeple (interior). Smalt pigment.
11 The pigment known as "earth green" contains glauconite (green-yellow) and celadonite (green-blue) minerals. The colour of the pigment depends on its mineral content. At the same time the alteration of these minerals in goethite (yellow iron oxide, FeO(OH)) is possible [6].
THE CHURCH OF VORONET MONASTERY
34 e_conservation
Exterior wall painting practiced since the end of
the 15th century in Bukovina, as the former western
facade from the time of Stephan the Great proves,
reached its highest glory in the 16th century during
the reign of Peter Rares. The exceptional paint-
ings conservation state in the severe climate of
Bukovina surprises even more as it is known that
the blue pigment is the first one to fade away
under the influence of climatic factors. The good
conservation state of the azurite, malachite and
relief decorative pearls on the garments should
be primarily attributed to the use of binders and
a special execution technique, different than that
of traditional Byzantine fresco. The blue colour
intensity shows on the one hand that the binder
can not be lime (calcium carbonate) which turns
white during the drying of the colours with which
it is mixed. On the other hand, the glossy aspect
and hardness of the mortars used for the pearls,
in contrast to the plaster surfaces of the wall, also
show evidence of use of other binder than pure
lime. Most existing scientific studies as well as
handbook descriptions refer to the interior paint-
ing technique. Known cases of outdoor murals,
especially in Central Europe - with a milder climate
than Bukovina, were executed with binders con-
taining proteins (calcium caseinate) besides pure
lime. This binder’s use is reported by Alexander
Eibner (quoted by Mora and Philippot) [7, 8],
especially in the 16th century, but their conser-
vation state, particularly that of the blue pigment
under the influence of climatic factors, is not yet
known [8].
As previously mentioned the 1547 painting from
Voronet was executed on a plaster based on lime,
sand and brick dust12 that distinguishes itself by
a special resistance to environmental conditions.
The painting technique was certainly a mixed one:
beginning with the application of a fresco back-
grounds and continuing with the application of
colours that contain organic, proteinaceous bin-
ders [9, 10], on a not completely dry plaster
(intonaco). Among the proteins used as binder,
casein-lime combination is the one conferring a
superior resistance. The mixture, called calcium
caseinate, was made of fresh lime and cow cheese.
To the superior resistance of the paintings have
also contributed:
- The special compatibility of the crystalline pig-
ments (azurite, malachite, calcium carbonate)
with the binder, compared with colloidal earth
pigments (ochre, ochre red, green earth);
- The fungicide effect of copper pigments (mala-
chite and azurite) which prevent the development
of micro-organisms that deteriorate the organic
binders in wall paintings in favourable environ-
ments;
- The superior mechanical resistance of calcium
caseinate than the one of calcium carbonate.
The use of a proteinaceous binder is proved by
the formation of a specific reaction, known as
biuret reaction, in which proteins in strong alka-
line environment in the presence of copper ions
show violet colour [11]. Copper ions can result
from azurite or traces of other copper minerals
that can be found sometimes with the pigment
and that react chemically easier (Image 14).
Regarding the application of azurite, it is possible
that it was applied as described in Paolo Benzi’s
article [5, 11]. Examining the stone inscription
12 The results of the chemical analyses performed in 1964 at the Institute of Design and Research of Building Materials (IPCMC) on some samples of fresco plaster from the exterior painting of Voronet, sampled from the inferior register of the south and north facades are the following: 28.16 - 28.67% loss in calcination, 34.5 - 37.18% insoluble substances in HCl, 1.63 - 2.54% SiO2, 32.98 - 35.12% CaO, 0.06 - 0.24 % MgO, 1.11 - 1.67% R2O3. From the discussion had on that date with Prof. Dr. Al. Steopoe, it was concluded that due to the very small quantities of taken mortar samples (2-5 grams), the results have a local significance. Only average samples obtained from greater quantities of mortars can give results to characterize the properties of the plasters.
IOAN ISTUDOR
35e_conservation
Image 14. The north facade (to west), above the door. On the white stripe the violet colour can be observed (biuret reaction), which proves the presence of an organic binder.
above the entrance of the narthex (originally on
the west facade of Stefan’s church), traces of
blue colour can be seen on the background of the
letters. The colour is azurite applied directly onto
the stone, which was only possible by adding an
organic binder in the colour (Images 15, 16).
On the south facade (west to the entrance door)
the presence of an organic binder in the colour
layer is also demonstrated by the black colour of
the Bishop Grigorie Rosca’s headcovering, which
shows an intense and glossy aspect and is very
resistance to exposure. This colour effect can not
be obtained in fresco technique (Image 17, 18).
Analysing the conservation state of the colour
layers from the facades it can be observed that
the deterioration prevails on the areas exposed
to the wind - north and north-east. At Voronet,
as well as in other churches with exterior
painting from Bukovina, it can be seen that the
Images 15 and 16. Exonarthex, east wall. Stone inscription, 1488 (left) and visible traces
of azurite on the background of the letters (right).
Image 17. South facade, portrait of Bishop Grigorie Rosca. The headcovering of intense black tone can be noticed.
THE CHURCH OF VORONET MONASTERY
number of well preserved colours decreases grad-
ually from east to north, azurite and malachite
pigments being the best preserved ones, both
in backgrounds and garments, while earth pig-
ments (ochre, ochre red, green earth) have a
smaller resistance (Image 19).
The detachment of the colour layer, observed at
all churches with exterior painting, occurs as a
result of humidity migration from plasters, fa-
vouring soluble salts - especially calcium sulphate
- to evaporate on the surface. Recrystallisation
of calcium sulphate close to the surface in pores
or microfissures, and the formation of dehydrated
gypsum (CaSO4.2H2O), occurs with cca. 1.6 times
increase in volume. This exerts pressure on the
mortar particles, breaking their cohesion and
the calcium carbonate crust from the surface,
resulting in the detachment and exfoliation of
the colour layer.
Also, the inferior registers are more deteriorated
than the superior ones which have been protected
by eaves. This phenomenon was the reason of
eaves’ enlargement during the restoration works
carried out in the ‘60s of the last century.
The natural aging of materials can be seen at Vo-
ronet, as in other churches with exterior painting,
by the particular exfoliation tendency of the
layers containing organic binders.
Examining the conservation state of the exterior
painting it becomes obvious that the last three
registers of the exonarthex added in 1547 (south
and north facades) are better preserved than
the areas painted in 1488 (Image 20).
We believe the different behaviour of the paint-
ings executed in 1547 is due to the colour layer
formation conditions and not to the execution
technique, otherwise impeccable. A possible
explanation may be that the painting executed
Image 18. Detail of Bishop Grigorie Rosca portrait. The intense tone of headcovering can be noticed.
Image 19. East facade. Erosion of the colour layer executed with earth pigments in the background and garments area.
IOAN ISTUDOR
36 e_conservation
Image 20. North facade. The conservation state of the paintings from the exonarthex added in 1547 is superior to the areas built and painted in 1488.
THE CHURCH OF VORONET MONASTERY
37e_conservation
on the freshly built facades of the porch had bene-
fited of a greater quantity of moisture and lime
which allowed a slow pigment carbonatation,
while the facades of the old walls had available
only the environmental humidity and the intonaco
lime (Image 20).
Unfortunately the azurite, pigment with beautiful
colour and great resistance in normal conditions,
has been exposed to high humidity (by capillarity)
and altered, transforming in malachite (green).
This phenomenon is the result of a change in the
copper carbonate - copper hydroxide ratio from
2/1 (in azurite) to 1/1 (in malachite)13 [12]. A
very important part from the inferior area of the
scene "Tree of Jesse" on the south facade became
green [2, 3] due to the long period of exposure
to capillarity humidity (Images 21, 22).
Another phenomenon of azurite alternation, this
time due to the chlorine ions content in the into-
naco (accidentally), can be observed as green
13 Under normal circumstances, azurite is stable if the partial pressure of carbon dioxide in the air is greater than 2.4 mm Hg. Since the partial pressure of carbon dioxide in air is 0.24 mm Hg, azurite transforms in malachite in the presence of humidity [12].
Images 21 and 22. Cross-section of a sample from the area where azurite transformed in malachite (left) and south facade, azurite transformed in malachite in the inferior area of the scene "Tree of Jesse" due to capillarity moisture (down).
IOAN ISTUDOR
38 e_conservation
spots of atacamite14 ([CuCl2.3Cu(OH)2], basic
copper chloride) [3] (or paratacamite) on azurite
background, on a few scenes in the porch’s vault
(St. Apostle Filimon scene, Synaxarium – day
22 November and others) (Images 23, 24).
Conclusions
The conservation works of the mural paintings
from Voronet started in the last decades of the
last century under the coordination of Prof. Dr.
Oliviu Boldura and offered the opportunity of
collaboration between researchers from various
interdisciplinary fields (analytical chemistry,
instrumental analysis, microbiology, art history)
with conservators, for the application of scientific
methods to conservation.
The chemical analyses have determined the na-
ture and composition of the materials used in the
painting process (mortars, pigments, binders),
have identified the causes of physical and che-
mical altering processes of colour layers, have
emphasized the process of azurite and minium
alteration and provided knowledge on the exe-
cution technique.
Based on the research results above and from
literature, we can consider that the Moldavian
painters, knowing the Byzantine technique and
entering in contact with painters from Central
Europe that used binders in lime colours, have
combined the techniques of these two schools.
The result of this mixed process provided the
formation of a very effective protective layer of
the surface and allowed a better conservation of
paintings from Bukovina.
We can also state that only due to the procedure
employed by the Moldavian painters, the exterior
decoration of Bukovinean churches is much more
resistant to environmental factors when compared
with Byzantine, Central Europe and all other
exterior paintings, in general.
Images 23, 24. Porch vault. Green spots of alteration (atacamite) are visible on the azurite sky background.
THE CHURCH OF VORONET MONASTERY
39e_conservation
e_conservation40
Bibliography
1. Margaret Hey, "The Analysis of Paint Media by Paper Chroma- tography", Studies in Conservation, 3 (1958), pp. 183.
2. Ioan Istudor, "Un fenomen de alterare a culorilor in pictura murala de la Voronet", Revista Muzeelor, 2 (1), (1965), pp. 65 – 66.
3. Ioan Istudor, Notiuni de chimia picturii, Daim Publishing House, Bucharest (2007), pp. 92.
4. Julia P. Petrushkova and Natalie N. Lyalikova, "Micro- biological degradation of lead - containing pigments", Studies in Conservation, 31 (1986), pp. 65-69.
5. Paolo Benzi, "La Pellicolo pittore nella pittura mural in Italia, materiali e tecnice esecutive dall Alto Medievo al XIX seccole", in Le Pitture murali (tecniche, problemi, conservatione). A cura di Cristina Danti, Mauro Matteini, Arcangelo Moles – Centro Di, pp. 73 – 102.
6. François Delamare, Laurent Delamare, Bernard Guineau and Gilles-Serge Odin, "Couleur, nature et origine des pigments verts employés en peinture murale gallo-romaine", in Pigments et Colorants de l’Antiquité et du Moyen Âge, Colloque International du CNRS, Paris (1990), pp 103-116.
7. Paolo Mora, Laura Mora and Paul Philippot, Conservarea Picturilor Murale, Ed. Meridiane, Bucharest (1986), pp. 156.
8. Jean Rudel, Technique de la peinture, Paris (1957), pp. 16 and pp. 43.
9. Ioan Istudor and Ion Bals, "Contributii la cunoasterea materialelor folosite in pictura murala exterioara a bisericilor de secolul al XVI-lea din Bucovina si la unele probleme de tehnica", Revista Muzeelor, 5 (6), (1968), pp. 491-497.
10. C. Merticaru, I. Istudor, and Gh. Cimpeanu, "Investi- gation Concern the Outdoor Wall Painting on the 16th Century Monasteries from Bucovina, Romania", Art ’05 – 8th International Conference on ”Nondestructive Investi- gations and Microanalysis for the Diagnostics and Conser- vation of the Cultural and Environmental Heritage”, Lecce (Italy), May 15–19 (2005), Book of Abstracts, pp. 184.
11. Ioan Istudor, "Alteration de la Couleur observees sur les peintures murales des eglises de Bucovine", in Colloque sur la conservation des peintures murales, Suceava, Romania, June (1977), pp. 21 – 25.
12. Gerhard Banik, "Green cooper pigments and their alteration in manuscripts or works of graphic art", in Pigments et Colorants de l’Antiquité et du Moyen Âge, Colloque International du CNRS, Paris (1990), pp. 99.
*Part of the information in this article was presented
at "Testimonies of living history" communication
session, Voronet, 12-13 September 2008. Photos
by Ioan Istudor, Anca Dina and Magdalena Drobota.
Born on November 14th 1928, Ioan Istudor gradu-
ated from the Faculty of Industrial Chemistry, the
Polytechnic Institute in Bucharest in 1951 and
since then, he has been continuously working as
scientist in the conservation field.
During almost half-century of continuous research,
he performed analyses for more than 300 monu-
ments and established the main research labora-
tories for conservation in Romania: in 1962 – the
first national conservation laboratory of the Historic
Monuments Direction; in 1963 the laboratory of
the National Art Museum of Romania and in 1983
the laboratory of the National Art University in
Bucharest.
He was certified as Expert by the Romanian Ministry
of Culture in the research of several conservation
domains, he was awarded several Excellency and
Merit Diplomas for his entire professional activity
and he was attributed the National Order, Knight
Rank for his merits.
From 1975 to 2002 he taught applied chemistry
to Conservation-Restoration, Museology and
Monumental Art departments of the National Art
University in Bucharest. Since 1996 he is working
as researcher for the conservation company Cerecs
Art S.R.L.
He has published a large number of articles and a
book entitled Notions on the Chemistry of Paintings.
He was granted for the patent of his discoveries:
“The procedure of obtaining a transparent calcium
casein dispersion”, “Solutions for extracting and
transferring mural paintings by strappo” and “The
candle that does not produce smoke".
IOAN ISTUDORConctact: [email protected]
IOAN ISTUDOR
FORECAST OF CHEMICAL AGING AND RELATED COLOR CHANGES IN PAINTINGS
The article describes the potential application of thermodynamic
simulation to the problems of chemical aging of painting.
Qualitative and numerical results were obtained in a preliminary
investigation by applying the method to various mixtures of
pigments without and with atmospheric components. The results
were compared to historic recommendations on incompatible
pigment mixtures with about an 80% match regarding potential
color changes in the aged mixtures of pigments. Results for the
cadmium yellow-lead white and cadmium lemon-emerald green
mixtures are illustrated by pictures, gradually showing color
changes related to aging. The method of thermodynamic
simulation can be a powerful tool to investigate old paintings,
in developing new materials, in conservation and restoration,
and to forecast some aspects of the aging of real paintings.
by Boris Zilbergleyt
e_conservation
BORIS ZILBERGLEYT
42
Introduction
Color is, obviously, the most important element
in a painting but also the most sensitive to degra-
dation factors. From fading to darkening, color
changes of paint layers that occur with time can
alter the entire appearance and perception of a
painting. Painting collections in world museums
abound with altered canvases due to internal and
external deterioration factors and unfavorable
conditions that occurred before they were placed
in the controlled museum environment.
Although external deterioration agents, such as
environmental factors (temperature, humidity,
ultraviolet radiation, etc.) and biologic attack are
permanently putting works of art at risk, their
impact can be controlled and limited in many cases.
However, in the long term, the major reason for
color change of a painting is the inevitable chemi-
cal aging of the paint layers [1]. These changes
include alterations in the optical properties of
binders, and in the chemical and structural com-
position of pigments due to chemical interactions
between them, assisted by atmospheric species
[2]. Chemical deterioration, resulting from these
interactions appears to be immanent to the aging
process.
The aging patterns of paintings have been inten-
sively studied, and seem to be quite clear on a
qualitative level [3, 4]. Paintings are composed
of a complex of grounds, pigments, organic bin-
ders, and varnish and in an ideal case the fresh
paint layer contains well-encapsulated pigment
particles. The particles are separated from the
support (canvas, wood, etc.) by the preparation
layer, from each other by the binder, and from
the atmosphere by both the binder and varnish
layer. As long as the ground, binder and varnish
are intact, routine changes of paint layers are
extremely slow. But even in the most favorable
storage conditions, the upper layer often ages
faster than the inner layers. Initially, aging leads
to a change in the optical characteristics of the
varnish and to the formation of craquelure net-
works. Moisture and other atmospheric factors
sharply accelerate chemical interactions between
pigments and other components of the paint
layer leading to intensive changes in its chemical
and phase composition and to massive changes
in the color, brightness and contrast of the
painting.
What can we do and to what extent can we pre-
vent the chemical changes? Chemical aging of
paintings has been extensively studied although
a comprehensive understanding has not yet been
achieved. We are aware of historic recommenda-
tions from old masters on the incompatibility of
certain mixtures of inorganic pigments, such as
lead white and ultramarine among others, based
on the artist’s practical experience [5, 6]. The
technical execution of a work of art is another
important aspect to take into consideration, but
in any case, we need to understand on a quanti-
tative level the aging mechanisms of a painting.
Thermodynamic Simulation Method
The method of thermodynamic simulation consists
of the computer simulation of possible chemical
interactions within the paint layer to determine
the ultimate chemical and phase equilibrium
composition. It allows for numerical calculations
of the most probable final composition of the
paint layer, resulting from these interactions
when all changes are over and the system rests at
thermodynamic equilibrium. One can state that
in old works of art most of the possible chemical
processes, allowed by their pre-museum and mu-
seum storage conditions, are either completed or
the relevant changes are already well pronounced.
Knowledge of the chemical and phase changes in
the layer may help to predict optical/color changes
and structural damages such as detachment or
flaking of the paint layer.
e_conservation 43
FORECAST OF CHEMICAL AGING AND RELATED COLOR CHANGES IN PAINTINGS
The method can be implemented using most of
the known simulation software; we used the
simulation complex ASTRA-4 [7] and partly HSC
Chemistry [8]. Atmospheric pressure (0.1 Pa)
and a temperature of 293K (200C) were taken as
simulation parameters. In case of pair mixtures
of pigments, the mass ratio of main to admixed
components varied from 10:1 to 1:1. Taking into
account the relatively long lifetime of a painting,
atmospheric air as a natural mixture of oxygen
and nitrogen was present in the initial compositions
up to 10%, with moisture up to 5% of the air mass
and some typical pollutants like CO, CO2, some-
times SO2 and H2S up to typical concentrations
for urban areas.
In cases when not enough thermodynamic data
was available to involve some complex pigments
of interest into simulation, we used their essential
and often the major color carrying fragments. For
example, in case of lead white we used the data
for lead carbonate only; in this case simulation
was carried out with the fragment of the pigment
with known data instead of the whole compound.
The same situation occurred in case of ultramarine
and several others. Though in most cases this was
good enough to judge the possible color changes,
the results of this work should be considered
qualitative for manifesting the method’s ability
to predict and describe the chemical aging of
paintings.
Simulation Results
For several chosen groups of pigments we tried
chemical interactions within the group between
the comprising pigments along with simultaneous
interactions of these pigments with atmospheric
components; lead white and zinc white with some
pigments in presence of atmospheric components;
oxide pigments in mixtures with sulfide pigments;
special pairs of pigments to check the historic
incompatible pigment couples, and some complex
mixtures from Rubens palette.
Among these mixtures, the incompatible pigments
group is one of the most interesting in the light
of this work. Corresponding results are shown in
Table 1. In some cases, when both dark and white
substances were formed together in the mixture,
such as FeS, CaS, and Na2CO3 in ultramarine mix-
tures with ochres and umbers, it was difficult to
evaluate if optical changes would happen. Also,
gaseous reaction products are not shown in the
table.
Even with this restriction, in about 80% of the
investigated mixtures the predicted possible
optical changes have certainly matched the
historic alterations. What is remarkable is that
the method of thermodynamic simulation also
explains possible reasons of the changes in terms
of chemical and structure composition thus allow-
ing for visual interpretation. Percentage of the
matching Y/N compatibility results in Table 1 is
high enough to prove the applicability of the
method to the analysis of chemical aging of paint
at least on the qualitative level. The quantitative
results, even if more difficult to obtain, will defi-
nitely offer more information. Table 2 contains
numeric simulation results of the incompatible
mixture of lead white (represented by lead car-
bonate) with yellow cadmium (represented by
cadmium and zinc sulfides).
The abbreviations for colors are B for black, W
for white or light colors, and Y for yellow. To ac-
count for reduced thermodynamic activity of the
lead carbonate (PbCO3) due to its binding into
lead white (2PbCO3.Pb(OH)2), its thermodynamic
activity coefficient was reduced to 0.6 for simu-
lation. One can see changes in the chemical com-
position of the mixture due to decay of input
basic color carriers, certain structural changes
due to the presence of new components, and
drastic color changes in the presence of black
lead sulfide. Figure 1 shows color visualization
of the simulation results, RGB indices were calcu-
44 e_conservation
lated using data for yellow cadmium from [9].
Mixtures’ color was calculated as weighted mean
of their components [10].
Table 1. Compatibility of various pigments in pair mixtures.N – not compatible, Y – compatible, Leg. - legendary, Sim. - simulated. Black or just dark colored species resulting from the chemical interactions are typed in bold.
PigmentsKnownoptical
changes
Simulated Compatibility
Base AdmixedNew species
able to changethe colors
Potentialcolor
changesLeg. Sim.
Lead white
Ultramarine
Darkening
Na2CO3, PbS,PbO2
Darkening
N N
Caput Mortuum N N
English Red N N
Cobalt Blue None None N Y
Dark OchreDarkening
PbDarkening
N N
NaturalUmber
Pb, PbO N N
Cinnabar None none None Y Y
Copperpigments
None none None Y Y
Cadmium Yellow
Lead White
Blackening
Pb, CdSO3
Blackening
N N
Massicot Pb N N
Lead Yellow Pb, PbO, Cr2O3 N N
Ultramarine Brightening none None N Y
Iron OxidesDarkening
Fe, Fe3O4, CdSO3
DarkeningN N
Umbers Cd, MnS, CaS N N
Terra diVerona
None Cd, CdSO3, MgO Probablynone Y Y
Cobaltpigments
Ultramarine Changingtone
Co, Na2SO4
Darkening
N N
Mn-Cd paint Not specified changes
Co N N
CadmiumYellow
None Co Y N
Ultramarine
Ochres Tonebrightening
FeS, CaS,Na2CO3
BrighteningN N
Umber N N
Copperpigments
Changingtone
Cu2S, NaOH Darkening N N
Cadmiumorange/red
Umbers None MnO Probablygraying Y N
BORIS ZILBERGLEYT
e_conservation
Figure 2 shows the aged samples of the cadmium
lemon mixture with emerald green, compared to
the initial colors (upper row); numbers on the
swatches show initial moles ratio cadmium /
emerald green in the mixture. Interestingly, that
cadmium pigment almost totally disappears in
all investigated mixtures after aging; its increase
in the initial mixture leads to more and more
pronounced grey color due to formation of dark,
fine dispersed particles of Cu3As and Cu2O along
with several white products.
Chemical Aging of Some Rubens’ Pigment Mixtures
Rubens was one of those rare artists who thor-
oughly wrote down the major components of the
mixtures he used in various purposes, sometimes
with a kind of functional names [11], that allows
us to experiment with his palette. Qualitative
results of the simulation of the mixtures aging
in presence of normal air (with typical presence
of moisture) are placed in Table 3.
Conclusion
This work presents the results of a computer simu-
lation aging experiment in the field of paintings,
where the information was collected from testi-
monies of old masters and from paintings, where
precise initial composition may not be known.
The data related to paintings aging and pigments
compatibility is transmitted and may vary from one
bibliographic source to another, sometimes with-
out clear references. Certain information defi-
nitely can be achieved after centuries of natural
aging or using accelerated methods, usually run
at conditions different than the natural ones, such
as elevated temperatures and moisture [1]. To the
best of the author’s knowledge, our approach was
the first attempt to use an experimental computer
simulation method to predict chemical aging.
Discussing the results of this work, one should
keep in mind that thermodynamic simulation
brings about the ultimate results of aging –
potential chemical and structural changes
providing that all possible interactions in the
Table 2. Numerical simulation results for yellow cadmium – lead white mixture chemical aging.
Figure 1. Color changes following chemical aging of 1:1 mixture of yellow cadmium with lead white, consequent stages at equal time intervals. The leftmost sample corresponds to a fresh mixture and the rightmost to the mixture, aged to the equi-librium limit.
Figure 2. Color changes following chemical aging of the lemon cadmium mixtures with emerald green, various initial
mixture contents. The leftmost swatches show accepted colors of pure mixture components.
Species PbCO3 CdS ZnS PbS ZnCO3 CdCO3 R G B
Initial amount, mol. 1.000 0.500 0.500 256 185 137
Equilibrium amount, mol 0.538 0.378 0.160 0.462 0.339 0.122 159 139 113
Color W Y B W W
45
FORECAST OF CHEMICAL AGING AND RELATED COLOR CHANGES IN PAINTINGS
46 e_conservation
ground-pigment-binder-varnish system are over,
that is the whole system rests in thermodynamic
equilibrium. Equilibrium compositions, in their
turn, should be considered as the limit towards
which the system moves, but not necessarily
achieves it in reality. Chemical aging advances
up to the latest stages of the painting lifetime
but is just one of the possible contributors to
the deterioration process.
Although the scope of this investigation was re-
stricted to inorganic pigments, the proposed
method is applicable to analyze chemical inter-
actions between any kind of substances including
organic dyes, binders and grounds. The increasing
abilities of computers essentially expand opportu-
nities for simulation and output of the simulation
results in such complex materials like paint mix-
tures. Besides that, the method can be used to
investigate chemical behavior not only of a paint-
ing but also of any art materials that change by
interacting with their environment. Although the
method investigates only one important aspect
of the aging of paintings, in certain cases its results
can help conservators to achieve a better under-
standing of the aging behavior of compatible and
incompatible pigment mixtures. Even though
color alterations are generally accepted as part
of the authenticity of a painting, this method may
help to establish the appropriate conservation
methodology.
The application of the method of thermodynamic
simulation in the field of aging is not easy because
only rare pigments are chemically simple enough
to have their thermodynamic properties ready in
Table 3. Predicted changes in various paint mixtures of Rubens’ palette.
Mixture color base admixture
Initial mixture for
simulationNew speciesafter aging
Possiblechanges
Neutralwhite
Lead white Cinnabar, ochre,organic black
Lead white,cinnabar, ochre,
air
Hg, PbO2,H2SO4
Darkening
Fleshcolor
Lead white
Cinnabar, krapplaquer,ochre, lapis
lazuli, azurite,organic black
Lead white,ochre,
ultramarine,azurite, air
Hg, PbS,Cu2S,
Na2SO4,Na2CO3
?
Blue Lapis lazuli,indigo
Azurite, cinnabar,
ochre, lead white,
organic black,smalt
Ultramarine,ochre, cinnabar,
azurite, leadwhite, air
PbS, Hg,Cu2S,
Na2SO4,Na2CO3,
NaOH
?
Yellow/Brown
Ochre
Lead white,organic black,krapp-laquer,
lapis lazuli,smalt, azurit
Ochre, leadwhite, azurite,
ultramarine, air
Fe, FeS,Pb, Cu,Na2CO3
Darkening
Green Azurite,malachite
Lead white Azurite, whitelead, air
CuO Darkening
Pigments Simulation results
BORIS ZILBERGLEYT
e_conservation 47
the regular thermodynamic data bases. Calculation
or recollection of appropriate experimental infor-
mation should be the first task prior to the method
implementation.
The author foresees many objections related to the
results of this article. Among them, why most of the
species, predicted in the run of that preliminary
investigation, were never reported by previous
investigators? Well, it could be that the works of
art, investigated earlier on, didn’t achieve the ex-
treme stages that could be qualified as equilibrium
in the context of this article. Or, what if they were
just overlooked because nobody suspected them
to be present?
Who might be interested in using this method?
We believe it can definitely help to investigate
possible reasons for the changes that occurred,
and how aging will develop. It could be also useful
for attribution purposes, solving the so called
back task of simulation (common in geochemical
simulation of the origination of minerals), that
is to find out the initial composition of the paint
mixture given the chemical analysis of the aged
sample. The manufacturers of art materials could
also use the method to evaluate their products
in various mixtures and environments. In general,
the method could be of a real help in finding proper
conditions of the accelerated aging. As concerns
to the artists, it’s of a very low probability that
Jackson Pollock would ever be willing to hear about
any simulation program, but Rubens definitely
might be interested to use it.
Acknowledgements
The original preprint of this article, prepared in
the main frame black-and-white computers era,
was published in a small amount of copies by the
Ministry of Culture of the USSR [12] with kind
support of Dr. L. Gorel’chenkova. Recently some
results were calculated anew to allow for color
References
1. R. L. Feller, Accelerated Aging: Photochemical and Thermal
Aspects, D. Berland, Ed. The Getty Conservation Institute,
Los Angeles (1994) http://www.getty.edu/conservation/
publications/pdf_publications/aging.pdf, accessed on
20/10/2008
2. A Study of the Discoloration Products Found in White
Lead Paint Films, http://aic.stanford.edu/sg/bpg/
annual/v04/bp04-04.html, accessed on 20/10/2008
3. Margriet van Eikema Hommes, Changing Pictures -
Discolouration in 15th to 17th Century Oil Paintings,
Archetype (2004)
4. Blakey, R. R. Evaluation of paint durability - natural and
accelerated. Progress in Organic Coatings 13:279–96
(1985)
5. Cennini, Cennino, The Craftsman's Handbook
http://www.archive.org/details/bookofartofcenni
00cennuoft, accessed on 20/10/2008
6. Odnoralov N. Materials in the Visual Arts. Moscow:
Enlightment (1983), pp.144
7. ASTRA-4. Modeling of chemical and phase equilibria
(manual). Moscow: MGTU (1991), pp.56
8. Outokumpu HSC Chemistry. Finland: Outokumpu
Research Oy, 2000, http://www.outotec.com/,
accessed on 28/10/2008
9. Web Color Definitions. http://endprod.com/colors/,
accessed on 28/10/2008
10. Color. Universal Language and Dictionary of Names, US
Department of Commerce (1976)
FORECAST OF CHEMICAL AGING AND RELATED COLOR CHANGES IN PAINTINGS
illustrations, and the paper in its new form was
made available on the Cornell University Library
site [13]. Current version contains some amend-
ments as well as special updates for conservation
professionals. The author is much obliged to
the people of e_conservation magazine, whose
attention, energy and help made this publication
possible.
CALL FOR SUBMISSIONS
e_conservation magazine is open to articles
submission on a wide range of relevant
topics for the cultural heritage sector.
Next deadlines for article submission are:
for Issue 9, February 2008 – submissions
due 1st January 2009
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manuscript when it is ready. Between the
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48 e_conservation
BORIS ZILBERGLEYT
11. Grenberg Y.I. Technique of painting. Moscow: Visual
Arts (1982), pp. 539
12. B. Zilbergleyt, Simulation of the Chemical Aging of
Painting with Computers, "Investigation of the Art
Remnants, their Materials and Techniques", Moscow,
Survey of the Ministry of Culture of the USSR (1989).
13. B. Zilbergleyt, Forecast of the Chemical Aging and
Related Color Changes in Painting (2005)
http://www.arXiv.org/physics/0505037.
Boris Zilbergleyt, born in Ukraine, lived
mostly in Russia and since 1991, in the USA.
He has a bachelor's degree in Computer
Science, a master's degree in Metallurgy and
a PhD in Chemistry/Physical Chemistry.
He worked as engineer and R&D scientist in
the fields of Metallurgy, Chemical
Engineering and Chemical Thermodynamics.
His interests include research in discrete
thermodynamics of chemical systems and
painting materials. Currently he is affiliated
with System Dynamics Research Foundation,
Chicago, USA.
BORIS ZILBERGLEYTSystem Dynamics Research Foundation
Contact: [email protected]
Photo I. Kresz
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dyRED MAITREYA TEMPLE - LEH, LADAKH Mural Conservation Project
by Anca Nicolaescu and André Alexander
A Tibet Heritage Fund Program
Part 2
Conservation Treatment
The conservation project described in the previous
number of the magazine had started in 2005 and
is still ongoing.
The whole project concept was built on the use of
natural materials due to their compatibility with
the original and availability in the area. Synthetic
materials were used either in cases where the
natural ones were inefficient or just for trials to
be able to observe their results periodically for
future investigations.
Firstly preventive treatments for addressing the
causes of damage or decay of the murals and the
architectural systems they embellish were preferred.
The THF team of architects, after extensive surveys
and building analysis, found that the building is
sound but that the parapets were badly disinte-
grated and the top soil and clay roof layers needed
to be re-done.
Therefore, the first interventions were done on
architecture structure in order to stabilize the
conservation state of murals. The small roof
above the Maitreya statue was restored; water
spouts were replaced and improved and the roof
parapets were extensively repaired using slate
stone for water proofing. At the floor level the
area from the north side of the ambulatory was
temporary raised by layers of rubble stones in
order to stop the water infiltration, the main
cause for the original painting losses in that
area. The stone layers do not transmit water and
serve as a convenient walking ground to see the
remaining paintings while performing circum-
ambulation.
For weathering protection the opening from the
end of the north wall was closed (Figures 1, 2).
The remedial interventions were based on system-
atic in situ research of materials and their behavior.
Trials were done prior to any decision taken and
extensive treatments were firstly done only on
the most endangered areas where more losses of
surface could have occurred otherwise.
One of the initial tasks was to establish the real
extent of the original paint surface which was
covered with two and sometimes three different
e_conservation 51
RED MAITREYA TEMPLE CONSERVATION PROJECT
Figures 1 and 2. For weathering protection the opening from the end of the north wall was closed.
plaster layers. Moreover the mortar used for the
infilling of the gaps was overlapping the edges
of the original painting.
Based on the results of the stratigraphical trials
done and recorded previously (Figure 3), the
first interventions at the support layer began
with the removal of the improper previous
fillings, starting from the edges in order to
protect the original surface and to avoid further
losses of original support.
The mortar layers were removed one by one very
carefully by mechanical means, starting with dif-
ferent types of scalpels, chisels or fiberglass sticks.
In larger areas where the painted surface was
stable a small hammer and chisel were used.
After this intervention, mortar traces remained
on the paint layer but they were left for further
more specific cleaning operations.
Figure 3. Example of stratigraphic trial sheet made for identification of the mural painting edges on the west wall.
ANCA NICOLAESCU and ANDRÉ ALEXANDER
52 e_conservation
The most important interventions at the support
level were the infilling of the gaps and consoli-
dation of the detachments.
Several testes were carried out in order to establish
the suitable composition for mortar and grout,
compatible with the original one.
For fillings, the composition was based only on
locally available materials: earth, sand, local
clay (markalak1) and organic inclusions – straws,
same as used in the painting support (Figure 4).
Observing the original existing mortars we set
up the characteristics to be followed for the new
material:
- porosity;
- mechanical resistance;
- adhesive power;
- workability;
- linear shrinkage.
For observation the mortars were applied on mud
bricks or/and directly on the walls.
The goal of the test phase was to choose the right
composition, proportion and size of the ingredi-
ents in order to find a good material with similar
physical-mechanical, plasticity and linear shrink-
age characteristics.
Two types of mortar were chosen; one rough for
filling in the deep gaps of the support layer and
a finer one for the final layer.
The rough mortar composition was: sand 1p +
gravel 1p + medium earth 4p + markalak 1p +
straw, which mainly offered good mechanical
qualities due the well-shaped grain size distri-
bution of the aggregate, minimal shrinkage,
good adhesive power, and a suitable hardness
relative to the original plaster. From the work-
ability point of view its coarse characteristics
permit a thick layer application useful for deeper
gaps, avoiding the application of too many layers,
which can lead to future damages. Moreover its
rough texture enables better attachment for sub-
sequent plaster layers.
For the fine mortar the mixture chosen was: fine
sieved sand 1p + fine sieved earth 2p + markalak
0,5p, which had very good adhesive power, cohe-
sion and stability and at the same time a similar
hardness and porosity to the original intonaco
plaster.
Beside its function of securing the area of the gaps,
this last mortar layer should have an aesthetical
impact on the final perception of the murals, thus
the color and texture were factors in choosing its
composition.
The mortar was applied using spatulas or special
trowels in successive layers leaving a sufficient
time for drying (Figures 5-8).
Figure 4. The local materials used for mortars and injection grout.
Figure 5. Filling of the support gaps.
RED MAITREYA TEMPLE CONSERVATION PROJECT
e_conservation 53
1 Markalak is local clay consisting of 62% clay, 30% calcium carbonate and 8% silt.
54 e_conservation
The surface of the final layer of mortar which was
part of the final aesthetical presentation was
washed very carefully at the end with a special
absorbing sponge in order to obtain an even and
slightly rough aspect for both the aesthetical
appearance and future interventions reasons
(adherence of some other layers if necessary in
some areas) (Figure 9).
For the consolidation of the support detachments
different grout mixtures were tested for desired
performance characteristics and working proper-
ties. The ingredients used in trials were: local ma-
terials - clay (markalak), yellow earth; different
additional components as pumice, glass micro-
spheres (Scotchilite K1™), Casein, Acril 33, Syton
X30 and small quantities of whipped egg white
(Figure 10).
Different types of grout have been injected for
observations in mud bricks and sometimes
original plaster fragments were grouted in situ
to evaluate their adhesion (Figure 11, 12).
Beside the compatibility of the grout with the
original support which so far has been done only
experimental in situ (further scientific and sys-
tematic research is required for an extensive
treatment), another important selection criteria
was the water quantity required by the respective
composition. Having in mind the sensitivity to
water of the original mural components, more
water than necessary can be harmful for physical,
chemical and mechanical reasons: dissolution,
expansion/contraction, salt migration and risk
of detachment can result. Also, yellow stains
appear due to the organic materials from the
support2 (Figure 13).
Figures 6-8. Different stages during the filling of the support gaps with mortar.
ANCA NICOLAESCU and ANDRÉ ALEXANDER
Figure 9. The final layer of mortar, applied under the original level of the painting was washed for obtaining a rough aspect.
Figure 10. Materials tested for the grout.
2 The appearance of the yellow stains was avoided by a thick Japanese paper facing glued with Klucel G (hydroxypropyl cellulose) in ethanol. Thus the stain was remaining on the paper – the evaporation was done at this paper level.
e_conservation 55
Two mixtures had good results so far after observ-
ing their behavior during the injection (fluidity
and sedimentation) and after drying (retraction,
cracking, adhesive power and water drop absorp-
tion):
- yellow earth, markalak and Syton X30 3%: 10ml
which was injected in small endangered area and
had very good results from the adherence point
of view (Figure 14);
- yellow earth, markalak, pumice, Scotchilite and
whippet egg white3.
RED MAITREYA TEMPLE CONSERVATION PROJECT
For extended treatment it is important to be
able to evaluate the results several months after
the intervention and to re-orientate the method
if necessary.
Figure 11. The observation of different types of grout injected in mud bricks.
Figure 12. Tests for grout injection in mud bricks.
3 From the available Getty Institute’s literature regarding organic materials in murals – example of grout mixtures used in Dunghuan caves for support consolidation.
Figure 14. Consolidation of support small detachments.
Figure 13. Organic components of the support can produce yellow stains on the original, this was avoided by using Japanese paper facing.
56 e_conservation
Figures 15 and 16. Removal of the white wash (upper) and of the markalak layer (lower).
Interventions at the paint layer level
The main treatment problem at this level was posed
by the overcoating layers which were covering
the original. As mentioned in the conservation
assessments, the paint layer being water sensitive
and already damaged (flaking and powdering
were occurring before the overcoat was applied),
it suffered even more deteriorations during the
over plastering due to both the very liquid appli-
cation and perfect compatibility between the
original and the overcoat layers. Thus the paint
layer and the new plasters interacted forming a
common mass which in some areas was almost
impossible to separate. Particularly, the first
overcoat layer (markalak) produced in time (or
even from the beginning, during its drying process)
grave damages due to a very good adherence,
strapping the original which was more adherent
to the overcoat than to the original support.
Therefore, the treatments were combined, most of
the time the removal of the overcoat layers being
alternated with the fixation of the paint layer.
Several materials and methods were tried in order
to elaborate the best approach.
Removal of the overcoat layers
Following stratigraphical trials we determined
that two main layers were covering the original:
the first one in direct contact with the paint layer
was a very uneven layer of markalak while the
second was a thin white wash. The upper parts of
the walls were covered only with the white wash.
Removal of the white wash
The white wash layer was very powdery and not
adherent to the surface thus easy to be removed
by soft brushes or very absorbent sponges wetted
with a very small amount of water (Figure 15).
However, the operation needs attention due to
the detachments existing in the markalak layer.
Also in the upper parts where this layer was ap-
plied directly on the powdering paint surface the
removal was done carefully with dry cotton swabs.
Removal of the markalak layer
The removal of the markalak layer was the most
difficult and time consuming task due to the wide
range of damages on the original paint layer and
the tight connection between the paint and the
overcoat layers.
Tests were carried out prior to the intervention
for setting up the right methodology specific for
each color, area or existing damage.
Considering the paint layer's sensitivity to water,
we used mainly dry mechanical methods (cotton
swabs, different types of brushes, scalpels, fiber
glass pencils, wishab sponges) (Figures 16-22).
ANCA NICOLAESCU and ANDRÉ ALEXANDER
e_conservation 57
RED MAITREYA TEMPLE CONSERVATION PROJECT
Figures 17-22. Different cleaning methods used simultaneosly or according to the state of the paint layer: hard brush for the markalak layer (upper left), dry cotton swabs or moisted with isopropyl (upper right), cotton swabs used in parallel with soft brush (middle left), cotton swabs with scalpel (middle right), eraser (lower left) and aspect of the area after cleaning (lower right).
Figures 23-26. Different aspects during the cleaning of the overcoating layers.
Where the markalak was very thick or uneven ap-
plied, the area was first thinned until an even thin
layer was obtained so that the paint layer under-
neath could be easier controlled and checked.
We tried to improve the results of the dry mechani-
cal method using in parallel chemical cleaning.
Several solvent mixtures were tried but the best
results were obtained with isopropyl alcohol used
in powder cellulose poultry (Arbocel BC 200) ap-
plied on the markalak layer. The markalak became
more powdery this way and easier to remove
without affecting the sensitive paint layer. This
solution however was not possible to use on areas
with detachments or flaking colors.
Depending on the colors, their conservation con-
dition and behavior during the tests, different
techniques and tools were used in parallel (Fig-
ures 23-28)
For a better view of the treatment results in
connection with color, damages and methods,
our observations for each color behavior and
cleaning technique were gathered (see Table 1).
58 e_conservation
ANCA NICOLAESCU and ANDRÉ ALEXANDER
Figures 27 and 28. Different aspects during the cleaning of the overplasters.
e_conservation 59
RED MAITREYA TEMPLE CONSERVATION PROJECT
Table 1. Observations during the cleaning of the west wall (first year’s intervention). Other recordings were added later.
60 e_conservation
ANCA NICOLAESCU and ANDRÉ ALEXANDER
Color Location Technical details
Condition Behaviorduring cleaning
Method used Observations
Black Contour drawings, figures
Thin and compactlayer
Stable; small losses that occurred before the markalak was applied
Very good Scalpels, brushes, cotton swabs; alcohol+ water (2:1)
Very resistant
White Flowers, jewelry, figures
Applied in a thin layer on the ornaments
Very adherent to the markalak layer
Very sensitive
Soft brushes, cotton swabs
Difficult to recover; weak adhesion to the background; consolidation necessary during cleaning
Earth green
Ornaments, flowers
Applied thicker; absorbed by the ground
Mostly flaking; still stable due to its connection with the surrounding colors
Good on compact surfaces; flaking areas
Soft brushes, cotton swabs, wishab
Good results; crust can break at the use of the scalpel; time consuming operation
Blue-green
Background, sky, ornaments, lotus
Thick layer Separated in layers, one layer connected to markalak; crust; damaged before the overcoating
Cold red Background, figures, clouds, hands, mandalas
Applied on 2 layers: a very thin preparation layer (fire) and a ticker one (ornaments)
Damaged before the markalak (technical deficiency); flaking in some areas; powdering (upper part)
Very good; powdering due to water leaks (upper part)
General good condition; areas where a thin layer remained on the surface were cleaned by brushing; consolidation with fish glue afterward
Warm red - orange
Deities hair, clothes
Very opaque; good covering power
Powdering Sensitive Cotton swabs; smooth brushes
Consolidation is needed afterward
Orange Ornaments, background, clothes, underlines
Thick layer, less binder
Powdery; weak adhe-sion; very adherent dirt; damaged before the overcoating
Sensitive Cotton swabs, scalpel, fiberglass sticks.
General good condition. Consolidation is needed afterward
Pink Some ornaments, underlayers
Very thin layer Washed out Difficult due to its thinness
Cotton swabs Very difficult removal of markalak
Purple Lotus flowerClothesClouds
Thin layer on white
Seriously damaged before the markalak; flaking; strapped in some areas
Difficult Cotton swabs, fiberglass sticks
Very difficult removal of markalak; consolidation during the cleaning
Dark blue Very thick layer, absorbent, hard, matte aspect
Poor condition, flaking, strapped by the marka-lak; Damaged before the overcoating
Among the most difficult to clean
Soft brushesCotton swabs
Very difficult, several trials of consolidation during cleaning
Light blue
First platform, Gurgon deity
Very thin layer, absorbed by the preparation layer
Seriously damaged before the markalak; strapped
Very difficult Soft brushesCotton swabs
Parts of the fine grey details were saved. Consolidation during the cleaning
Grey Lotus flower,Clouds,Snakes
Thin layer Stable on the snakes and ornaments. Con-nected to the markalak in some areas
Generally stable
Compresses with isopropyl; fiberglass stick
Yellow Traces in some areas
Instable, powdering Difficult It was applied as underpaint layer for the gilded areas
We found this useful for both correlating the
damages and the appropriate approaches as well
as for future research regarding this issue.
During this process the paint layer was fixated
simultaneously or/and consecutively using dif-
ferent methodologies further described.
After the entire area was already consolidated a
last cleaning was done by the mean of wishab
sponges in order to remove the white veil which
remained from the markalak dust.
Fixation of the paint layer
The fixation of the paint layer was imperative
due to the high degradation level which would
definitively have led to large losses.
On the other hand, this operation implied the
use of a fixative material which, if its choice is
not based on sufficient research regarding the
original materials, damages and effects, could
produce undesirable consequences in the future,
leading even to grave changes of the initial
proprieties and conservation condition of the
original.
Therefore we chose animal glue as fixative, which
is very compatible with the original (knowing
that the original binding agent was animal glue),
avoiding thereby unexpected future reactions.
After checking the local animal glue used as binder
even nowadays we decided that its level of chemic
impurity (color and unknown particles) could
affect the original. Therefore it was decided to
use the fish glue injected or sprayed depending
on the damages type (powdering or flaking
paint layer).
Some other fixatives were used but only in areas
where the animal glue was not effective or in
trials for future observations and research, being
aware that future investigations and periodic
evaluations of the results are needed in order to
re-orient the method if necessary.
Thus, the different materials and methods used
according with the damages necessities were:
Fish glue (2-4%)
For the powdering areas the warm glue was
sprayed (Figure 29) on the surface. Depending
on the absorption level of the paint layer some
alcohol was sprayed before for a better penetra-
tion. After the fixative was totally absorbed by
the paint layer the surface was gently pressed
with a special rubber roller over a layer of Japa-
nese paper and a layer of polyester foil (melinex)
applied as protection (Figure 30). Observing the
behavious of the surface after the treatment,
sometimes the operation was repeated. Very
good results were obtained with this method -
the adherence was reestablished and the original
paint aspect preserved (Figures 31, 32).
e_conservation 61
RED MAITREYA TEMPLE CONSERVATION PROJECT
Figure 29. Fixation of the color by spraying fish glue. Figure 30. Pressing of the paint layer.
For a better control of the penetration of the
glue into the big flaking areas it was seen that
injected fish glue gives very good results. This
approach was used for some areas, the metho-
dology afterwards being the same as described
above.
For consolidating the paint layer strapped by the
markalak the warm fish glue was injected in the
damaged area (Figure 33) then the surface was
laid down on the support by means of a spatula
or special rubber roller (Fıgure 34). The adher-
ence of the paint to the support was resolved in
this way but the markalak layer became harder
to remove as the glue was absorbed by the marka-
lak layer and thus the paint layer could have suf-
fered damages during the cleaning (Figure 35).
Therefore more trials with different materials
were required for obtaining better results.
Paraloid B72 (5% in acetone)
Trials were also done with Paraloid B72 for con-
solidating the paint layer strapped by the marka-
lak. Japanese paper facing with CMC was applied
on the markalak and the detachment was opened.
ANCA NICOLAESCU and ANDRÉ ALEXANDER
62 e_conservation
Figures 31and 32. Before and after the fixation treatment of the paint layer.
Figures 33 - 35. Paint layer consolidation.
Paraloid 5% in acetone was applied on both the
back of the strapped paint film remained on the
markalak and on the support area from where
the paint layer was strapped (Figure 36).
When the Paraloid was dry, acetone was brushed
on the support surface in order to reactivate it
and the strapped fragment was pressed back on
the support using a special rubber rolle (Figure
37). After the perfect drying of the surface, the
facing was removed by wet cotton swabs and the
markalak was removed mechanically or with a
mixture of water – isopropyl (Figures 38, 39).
This method had good results but only where the
paint layer was compactly strapped by the marka-
lak and not very connected to it. The fixed paint
layer suffered no changes in its original matte
aspect.
For areas where only small fragments of the origi-
nal color were strapped the method did not work
due to both the difficulty of applying Paraloid
on small support lacunae (from where the color
was strapped) and the fast evaporation rate of
the acetone (not enough time to be applied on
all of the fragments without getting dry or over
touching the surrounding areas).
Further research will be useful for finding an
efficient solution for this specific paint layer
deterioration.
Rabbit glue (4%)
In the areas where the paint layer was detached
together with parts from the preparatory layer,
the rabbit glue was more appropriate to use due
to both its better adhesive power and its capacity
of creating a thin layer which could provide a better
ground for pasting of thick layers. The warm glue
was injected in the detachment area and pressed
with a spatula or a special rubber roller over a
melinex foil. In the areas where part of the support
was lost and the paint layer had nothing to lay on
we used as filler (before fixing the paint) sieved Figures 36-39. Fixation of the paint layer with Paraloid.
RED MAITREYA TEMPLE CONSERVATION PROJECT
e_conservation 63
earth in mixture with rabbit glue which was
applied by spatulas. Very good results were
obtained with this method, the paint layer
becoming stable.
Cleaning
Beside the removal of the over-plasters and the
mechanical cleaning with the wishab sponge as
described above, several cleaning trials were
done in the lower part of the west wall (on the
donors frieze) were dust and soot had altered
the original aspect of the murals due to the use
of the butter lamps.
Trials were carried out with different solvent
mixtures:
- acetone – alcohol (1:1) – the dust and remains
from the over-plaster removal were satisfactorily
cleaned;
- acetone - isopropyl (1:1) – better results;
- isopropyl in cellulose paste poultry (Arbocel) -
good results;
- isopropyl in Japanese and napkins poultry
pressed with a rubber roller – very good results.
Very good results were also obtained by mechani-
cal means, using fiberglass sticks of different
thicknesses.
Considerations regarding the final aesthetical presentation of the paintings
The temple, still regularly used for ritual purposes,
it is not preserved as historic monument but as a
living and active – even interactive – space be-
tween art, spirituality and those people who step
inside it.
From this reason an intervention strategy was
established for choosing an appropriate final
presentation, able to eliminate the divergences
Figures 40-42. Different aspects during the consolidation of the paint layer with rabbit glue.
ANCA NICOLAESCU and ANDRÉ ALEXANDER
64 e_conservation
between the correct chromatic retouching with-
out creating a fake and the recovery of the integrity
of the art work demanded by its religious function.
First of all, the lacunae were classified from two
points of view: stratigraphically, categorizing
them due to the level where they appeared: ero-
sions of the paint layer (irregularities of the paint
hue due to some slightly mechanical damages or
chemical alteration), lacunae in the paint layer
(losses of the paint layer), superficial support
lacunae (losses of the support at the intonaco
level) and deep lacunae of the support layer
(losses of the support at the arriccio level).
From the image perception point of view lacunae
were divided in several types: lacunae that can be
integrated (erosions of the paint layer), lacunae
which can be integrated by a reconstructive pro-
cess (they must be of small dimensions and located
in areas which preserve enough original elements)
and large lacuna fields which cannot be retouched.
This simple organization of the damages was
helpful for setting up a retouching methodology
where same types of lacunae were to be treated in
similar way on the whole ensemble for obtaining
a final unity.
Another aspect of the retouching stage was
choosing the right media to be used for pre-
serving the original matte aspect and being
reversible as much as possible.
Two types of materials were tried: pastels, which
are very easy to remove and mineral pigments
using as binder Klucel G in alcohol 2% (Figure
43). Pastels, besides having a good reversibility -
which sometimes could have been a disadvantage
(in the lower part where the painting can be easily
touched by visitors) – were not easy to apply on
small lacunae without touching the original.
RED MAITREYA TEMPLE CONSERVATION PROJECT
e_conservation 65
Figure 43. Retouching tests with pastels (left) and pigments with binder (right).
ANCA NICOLAESCU and ANDRÉ ALEXANDER
66 e_conservation
Figure 44. Ensemble before chromatic reintegration.
Figures 45 and 46. Chromatic reintegration by velatura.
Even though the area retouched using pastel
was reaching a good chromatic aspect, this
methodology was impossible to use on all types
of lacunae.
The trials done with Klucel G as binder and mine-
ral pigments gave very good results: easy to be
applied even on very small erosions and in same
time very reversible with alcohol which is not
affecting the water sensitive original murals.
Having chosen the materials to be used, the
retouching techniques were selected depending
on the nature of the lacunae. The very small and
superficial ones were integrated with a light
glaze which permits the recovering of the
surface evenness without the alteration of the
rest of the paint layer (Figure 45-48).
Retouching the lacunae of the paint layer that
were disturbing the image not only due to surface
alteration but also due to the small white or light
RED MAITREYA TEMPLE CONSERVATION PROJECT
e_conservation 67
Figures 47 and 48. Before and after chromatic reintegration.
ANCA NICOLAESCU and ANDRÉ ALEXANDER
68 e_conservation
colors of the appearing support was done by means
of transparent glazes (velatura) applied in dots
using neutrals colors. As a result, the white spots
of the paint gaps were optically pushed backwards
leaving the original readable.
The reconstructive method used for the superfi-
cial support gaps was the hatching technique
(tratteggio) using watercolors this time because
the retouching was done on new support, able to
be removed if necessary.
Community integration into the conservation project
Before THF’s project, there has been not a single
Ladakhi restorer. Conservation projects in the
region always involved only foreign or Indian
mainland experts. Therefore, the involvement
and training of locals was an important aspect
of the project.
RED MAITREYA TEMPLE CONSERVATION PROJECT
e_conservation 69
Figure 49. Chromatic reintegration of the paint layer.
Figure 50. Chromatic reintegration by tratteggio.
ANCA NICOLAESCU and ANDRÉ ALEXANDER
70 e_conservation
Figure 51. Before chromatic reintegration of the paint layer.
The two most promising students have completed
an internship in Germany at the conservation la-
boratories of Erfurt University of Applied Science
in May - July 2007. These two and other trainees
will participate in the project to gain further
training. They have already gained good knowl-
edge and skills regarding conservation issues
and respect of heritage authenticity and thus,
hopefully, they will be able to maintain their
valuable heritage in the future.
Conclusion
What we had presented in this paper are all our
experimental interventions and trials which must
be re-evaluated regularly and followed by more
systematic researches. That is the reason why the
needed extensive treatments were done only with
glue instead of the local animal glue, avoiding
hence uncontrollable future damages.
RED MAITREYA TEMPLE CONSERVATION PROJECT
e_conservation 71
Figure 52, 53. Chromatic reintegration of the paint layer.
At the end of this project, murals from the first
half of 15th century were recovered in Red Maitreya,
being now the oldest extant paintings in Leh.
Several key historic sites in Ladakh preserve com-
parable historic art, but almost all of them require
urgent conservation intervention. Many have been
lost in the past 2 decades. The investigation of
the paintings in the Red Maitreya Temple of Leh
has allowed first conclusions as to the technologies
and conservational challenges of early Western
Himalayan hoping that questions have been raised
for future investigations.
Anca Nicolaescu is a Romanian mural painting
conservator with Master degree from the Uni-
versity of Fine Arts Bucharest, Conservation-
Restoration of art works department.
She received recognition as specialist from the
Romanian Ministry of Culture in 2005 after having
coordinated various distinguished conservation
projects. One of the projects (a 17th century
mural painting ensemble) done by Restauro Art
Grup (the conservation enterprise where she is a
co-founder) was awarded in 2004 the "Vasile
Dragut" prize for Cultural National Heritage by
the Romanian Ministry of Culture.
Her work experience includes international par-
ticipation at conservation projects and seminars
in UK, Turkey, Uzbekistan, Japan and India.
ANCA NICOLAESCUContact: [email protected]
André Alexander was born in West-Berlin in the
Year of the Wood Dragon.
He currently divides his time between Ladakh,
China and Germany. He was trained by traditional
master craftsmen in Lhasa in traditional Tibetan
architecture, and is currently affiliated with Berlin
University of Technology (MSc in Urban Manage-
ment and PhD candidate in Architecture), where
he occasionally lectures. He is co-founder and first
chairman of Tibet Heritage Fund, an international
non-profit organisation working to preserve the
heritage of the Himalayan regions. He has a prodi-
gious publishing activity, from which several articles
and reports can be seen online on THF's website.
ANDRÉ ALEXANDERContact: [email protected]
THF - TIBET HERITAGE FUNDwww.tibetheritagefung.org
References:
1. Stephanie Bogin, A technical Study of the early Buddhist
wall paintings at Nako, India, Unpublished Master’s
thesis, Courtauld Institute of Art (2004)
2. David Jackson and Janice Jackson, Tibetan Thangka
Painting: methods and materials, Snow Lion Publications,
New York (1988)
3. Ann Shaftel, "Note on the technique of Tibetan Thangkas",
Journal of the American Institute for Conservation, 25 (1),
(1986) pp. 97-103
4. Leslie Rainer and Angelyn B. Rivera (ed.), The conserva-
tion of decorated surfaces on Earthen Architecture, Getty
Publications (2006)
5. Gernot Minke, Building with earth – design and technology
of a sustainable architecture, Germany, Birkhauser Basel
(2006)
Acknowledgments:
We wish to thank to the project sponsors Trace Foundation
New York and InWent Germany; Erfurt University of Applied
Sciences – Germany for their cooperation which made the
project possible thorough students volunteering (Hanna
Pohle, Derya Pektas, Jana Bulir, Olga Emgrund, Sonia Cabela,
Anke Farnik, Rebekka Ewert and Jovanna Glaß) and their
professor Meinhart Landmann; and to the devoted local
trainees Jangchen Dolma and Skarma Lotus. The National
Research Laboratory for Conservation and Restoration of
National Cultural Heritage (LNC) – Romania especially to
Prof. Gheorghe Niculescu Director of LNC and his team (Dr.
Olimpia Hinamasuri Barbu and Dr. Georgescu Migdonia) for
all the scientific research presented here.
72 e_conservation
ANCA NICOLAESCU and ANDRÉ ALEXANDER
book
revi
ew
e_conservation
CONSERVATION OF PLASTICSMaterials Science, Degradation and Preservation
Author: Yvonne Shashoua
Publisher: Butterworth-Heinemann
Publication Year: 2008
Pages: 300
ISBN 13: 978-0-7506-6495-0
ISBN 10: 0-7506-6495-9
Language: English
List Price: £49.99 (€72.95)
Review by Brenda Keneghan
The degradation of plastic objects in collections
has been a growing problem for museums and
galleries over the last 20 years; their sudden and
spectacular disintegration confounding conser-
vators more familiar with dealing with the gradual
decline of traditional materials. As plastic has
become ever more ubiquitous this problem is set
to escalate. The 1991 CCI conference Saving the
Twentieth Century started the ball rolling on
international discussions and a great variety of
case histories have been presented at conferences
over the intervening years. On the publications
front Anita Quye’s & Colin Williamson’s Plastics:
Collecting and Conserving (1999), immediately
springs to mind as a turning point on the subject.
But this excellent little book is almost 10 years
old and is targeted towards a general audience:
the amateur collector as well as the museum pro-
fessional. There has been a distinct gap in the
literature on this subject ever since. Now Yvonne
Shashoua’s Conservation of Plastics, has come
along and filled that gap in a most clear and
comprehensive manner. The book is a welcome
addition to the Butterworth-Heinemann series
of conservation and museology pub-
lications, and continues the same high
standards. Yvonne Shashoua is eminently
qualified to compile such a book, having
specialised in modern materials conser-
vation for several years in the British
Museum before moving to the National
Museum of Denmark to undertake PhD
research work into the degradation of
PVC. Her (2001) PhD thesis, 'Inhibiting
the deterioration of plasticized poly
(vinyl chloride) – a museum perspective'
has become a cornerstone in conserva-
tion science literature, applying rigorous
science to a practical heritage problem.
A major problem with the conservation of
plastics is that a certain knowledge of
chemistry is required before attempting
either an interventive or inhibitive
(Yvonne’s preferred term) treatment.
This book is intended to appeal to a wide
readership, including practical conser-
vation students and practitioners as
74 e_conservation
BOOK REVIEW
Example of plastics cleaning treatment, discussed in Chapter 7. Dirt deposits on the surface of a polyurethane foam shark model used in the Jaws films were mechanically cleaned to improve its appearance.
well as conservation scientists. This is a tough tar-
get to meet without frustrating or disappointing
someone, but the structure of the book facilitates
the gradual introduction of technological and
chemical principles in a neither an over-simplistic
nor patronising manner. Each chapter is preceded
by a very useful summary of its contents allowing
the reader to decide whether they wish to go more
fully into this area or not.
Almost by way of a summary, Chapter 1 tells us
where plastics are found in collections and finishes
with a brief word on the current status of plastic
conservation.
The following three chapters form a complete
introduction to plastics, beginning appropriately
with their historical development (Chapter 2)
and followed by their technological production
(Chapter 3) and their properties (Chapter 4). Each
of these three chapters is illustrated with attractive
colour photographic images and extremely com-
prehensive tables. In fact, the quality and content
of the images and tables throughout the book
is exceptionally high. Chapter 3 introduces the
chemical structures of monomers and describes
the polymerisation processes and resulting poly-
mers in the most painless manner possible. The
different types of polymerisation reactions are
described. There is also an extremely useful table
(Table 3.3) summarising the types, functions and
examples of frequently used additives. These
tables are a most valuable resource for both the
newcomer to the field and those more experienced.
The chapter ends with descriptions of the various
industrial processes by which the plastics are
transformed from granules or liquids into various
types of everyday objects. Chapter 4 presents an
overview of the chemical, optical and thermal
properties of plastics which are most relevant to
conservation. Chapters 5, 6 &7 (identification,
degradation & conservation) are, perhaps, the
chapters that non-scientists will immediately turn
to when first confronted with a degrading plastic
object. Identification by means of various tests,
e.g. hot pin, density, burn tests and solubility
are described (along with warnings as to their
dangers). Chemical spot tests are also described as
giving rapid identification, however never having
had any success with these myself, I must disagree
e_conservation
Reviewed by Brenda Keneghan, Polymer Scientist
Conservation Department - Victoria & Albert Museum
London SW7 2RL
BOOK REVIEW
75
with this statement. The chapter concludes with
a description of the various types of instrumental
analysis useful for polymer identification.
The opening sentence of the summary to Chapter 6
states "It is essential to understand the factors
causing degradation prior to developing an approach
to the conservation of plastics".
This is probably the most important sentence in
the entire book as experience has shown that the
"conservation" of plastics cannot be tackled in
the same manner as the conservation of more
traditional materials. This is due to differences
in chemical composition of individual plastics
and/or combinations of different factors being
responsible for their degradation. Chapter 6
describes in detail the degradation pathways of
the four most problematic plastics in museum
collections: cellulose nitrate, cellulose acetate,
plasticised PVC and polyurethane foam. Table 6.2
charts clearly and comprehensively the effects of
radiation, heat, oxygen and water on the major
plastics found in collections. Again this is a most
useful resource. Photographic illustrations of the
results of physical and chemical degradation bring
the message home.
Chapter 7 follows on logically from Chapter 6 by
describing current practice in the conservation of
plastics - inhibitive and interventive. The scientific
principles behind the use of various adsorbents
and scavengers are explained. Hopefully, this will
put an end to repeated recommendations for the
inappropriate use of Ageless that have been heard
over the previous few years. The pros and cons of
low temperature storage are outlined and explained.
The cautious approach that has been adopted
towards the seemingly simple procedures such as
cleaning and adhering plastics is explained and
supported by tables of solubility parameters and
surface tension values for solvents and plastics.
Having said this, the interventive treatments that
have been attempted are also described or refer-
enced. Finally, Chapter 8 looks forward to the fu-
ture of plastics conservation and suggests that a
way forward might be to develop an information
interface between manufacturers and users as
well as increased specialised training.
The main text is supplemented by three appendices
including a very useful mini-dictionary of degra-
dation terms (with accompanying photographic
images).
In summary, the book is very clearly and thought-
fully laid out. An enormous amount of painstaking
work has gone into sourcing the information from
both the scientific and conservation literature
and presenting it in such an accessible manner.
It is well illustrated with tables and photographic
examples. The references at the end of each chapter
are comprehensive and up to date. Conservation
of Plastics does not teach one how to conserve
plastics but it does provide a background that
will enable a conservator or conservation student
to make informed decisions on the advisability
of potential treatments. By providing information
previously difficult to obtain in a readily accessible
format perhaps more interventive treatments will
be attempted.
Yvonne states in the introduction that the purpose
of the book is "to distil the extensive knowledge
produced by the polymer and plastics industries,
designers, environmental and conservation pro-
fessionals into a single publication focussing on
the preservation and conservation of plastics".
I think she has succeeded beyond expectation
in this mammoth task.
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e-conservationline
No. 7, October 2008
ISSN: 1646-9283
Registration Number125248
Entidade Reguladorapara a Comunicação Social
Propertye-conservationline, Teodora Poiata
PeriodicityBimonthly
CoverPhoto by Anca Dina
Detail of the stone inscription fromthe church of Voronet Monastery (1488)
Executive EditorRui Bordalo
EditorsTeodora Poiata, Anca Nicolaescu
Collaborator:Anca Dina
Graphic Design and PhotographyAnca Poiata, Radu Matase
ExecutionTeodora Poiata
Address Rua Peixinho Júnior, nº 9, 1 D
2770-163 Paço de ArcosPortugal
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