the online magazine No. 7, October 2008

e_conservation

the online magazine

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

www.prorestauro.com

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

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e_conservation 5

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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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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.

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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: cbarata@porto.ucp.pt

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: ajcruz@netvisao.pt

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: marta.ferro@ua.pt

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: bistudor@gmail.com

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

for Issue 10, April 2009 – submissions due

1st March 2008

Nevertheless, you can always submit your

manuscript when it is ready. Between the

receival of the manuscript until the final

publication may pass up to 3 months

according with:

- the number of the manuscripts on hold,

submitted earlier by other authors

- the release date of the upcoming issue

- the pre-allocated space in the magazine

to each section

Please check our publication guidelines

for more information.

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: sdrf@ameritech.net

Photo I. Kresz

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case

stu

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: ancanicolaescu@yahoo.com

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: info@tibetheritagefund.org

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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