research in conservation

The Getty Conservation Institute

Oxygen-Free
Museum Cases

Edited by Shin Maekawa

Oxygen-Free
Museum Casesresearch in conservation

The Getty Conservation Institute

Oxygen-Free
Museum Cases

Edited by Shin Maekawa

1998

Dinah Berland, Managing Editor
Judith Abrahms, Manuscript Editor
Amita Molloy, Production Coordinator
Garland Kirkpatrick, Series DesignerPrinted in the United States of America
10 9 8 7 6 5 4 3 2 1©1998 by the J. Paul Getty Trust
All rights reserved.

Library of Congress Cataloging-in-Publication Data
Oxygen-free museum cases / edited by Shin Maekawa.
p. cm.—(Research in conservation)
Includes bibliographical references and index.
ISBN 0-89236-529-3
1. Museum conservation methods—Research. 2. Museum exhibits—Conservation andrestoration. 3. Mummy cases—Design and construction. 4. Material culture—Conservation
and restoration. 5. Cultural property—Protection. I. Maekawa, Shin, 1952. II. Series.
AM145.09 1998
069'.53—dc21
98-15964
CIP

The Getty
Conservation
Institute

The Getty Conservation Institute works internationally to further the appreciation and preservation of the world's cultural heritage for the enrichment and useof present and future generations. The Institute is an operating program of the
J. Paul Getty Trust.

Research inConservation

The Research in Conservation reference series presents the findings of research
conducted by the Getty Conservation Institute and its individual and institutional
research partners, as well as state-of-the-art reviews of conservation literature.
Each volume covers a topic of current interest to conservators and conservation
scientists. Other volumes in the Research in Conservation series include Inert
Gases in the Control of Museum Insect Pests (Selwitz and Maekawa 1998);
Stone Conservation: An Overview of Current Research (Price 1996); Accelerated
Aging: Photochemical and Thermals Aspects (Feller 1994); Airborne Particles inMuseums (Nazaroff, Ligocki, et al. 1993); Epoxy Resins in Stone Consolidation(Selwitz 1992); Evaluation of Cellulose Ethers for Conservation (Feller and Wilt
1990); Cellulose Nitrate in Conservation (Selwitz 1988); and Statistical Analysis
in Art Conservation Research (Reedy and Reedy 1988).

Contentsix

Foreword
Miguel Angel Corzo

xi

Preface
Shin Maekawa

1

Chapter 1 Conservation of the Royal Mummy Collection at the EgyptianMuseumShin Maekawa

7

Chapter 2 Protection of Objects from Environmental Deterioration
by Reducing Their Exposure to Oxygen
Eric F. Hansen

17

Chapter 3 Preservation of Historic Materials by Using Inert Gases for
Biodeterioration Control
Nieves Valentín

31

Chapter 4 Design and Construction of the CCI's Hermetically Sealed Display
and Storage Case
Shin Maekawa

47

Chapter 5 Controlled-Environment Cases for the Royal Mummy Collection
Nasry Yousef Iskander

53

Chapter 6 Preservation of the Original Documents of the Constitution of India
Hari Kishan and Shin Maekawa

59

Chapter 7 Preservation of the Mummy of an Egyptian Child in a Hermetically
Sealed Museum Case in Spain
Shin Maekawa

65

Index

71

About the Authorsvii

Foreword

Over the course of the last ten years, the Getty Conservation Institute has been
involved in projects that deal with oxygen-free environments as a means of preventing the deterioration of sensitive organic materials. The royal mummies of
Egypt, the original documents of the Constitution of India, and the Royal Proclamation Charter for Hudson's Bay Company, Toronto, are the most notable
examples of cultural objects conserved in this way. The research that led theInstitute to adopt this solution was originally conceived for the specific problem
of conserving the royal mummies at the Egyptian Museum in Cairo. The possibilities of other applications soon became evident.
This book covers the results of that research and its applications presented byseveral of the principal participants in the project. The purpose of this publication, in concert with other volumes in the Research in Conservation series, is toprovide information that will be of interest and use to conservators and conservation scientists.
Shin Maekawa, editor of this volume, worked long and hard to guide much of
the research and to give further coherence to the structure of the information
presented. While a fellow at the GCI, Nieves Valentín first pointed the Institutein the direction of this research; her further responsibilities in Spain allowed her
to continue along the lines she first established at the Institute. Nasry Yousef
Iskander implemented much of the results in constructing cases for the EgyptianMuseum in Cairo. Our gratitude is extended to each of these contributors.
Dinah Berland and her editorial colleagues have given this publication a notable
readability, and Amita Molloy coordinated the book's production. Our sincere
thanks to them. To our readers, I express the hope that you will communicate
your comments to us, so that future volumes in this series can be further geared
to the needs of the profession.
Miguel Angel Corzo
Director
The Getty Conservation Instituteix

Preface
Shin Maekawa

In 1987, the Egyptian Antiquities Organization of the Egyptian Ministry of Culture and the Getty Conservation Institute (GCI), based in California, undertook acollaborative project for conserving the Royal Mummy Collection at the EgyptianMuseum in Cairo. Studies were carried out at the Getty Conservation Instituteon the efficacy of inert-gas atmospheres in preventing chemical and biologicaldegradation of proteinaceous materials in long-term display or storage. The
design and construction of a hermetically sealed, inert-gas-filled display andstorage case was carried out at the Getty Conservation Institute. The researchphase of the project ended with the presentation of a draft report and the delivery of a prototype hermetically sealed display and storage case to the Egyptian
Antiquities Organization at the Egyptian Museum in May 1989. Implementationof the results, including the local fabrication of the cases in Egypt and conservation of the mummies, started immediately thereafter. After the project had
ended, participants also continued research in their respective areas, with valuable new results. The Egyptian Antiquities Organization completed ten cases andopened the new Royal Mummy Room in March 1995. This publication was produced to disseminate the results of the project as well as to aid others who may
wish to consider the use of hermetically sealed cases—significant aids to thelong-term conservation of oxygen-sensitive objects.
Chapter 1 describes the background and development of tasks and summarizes
the results of the project. Environmental recommendations for display and storage of proteinaceous materials are discussed in chapters 2 and 3. In chapter 2,
Eric Hansen, an associate scientist at the Getty Conservation Institute, presents
the results of his investigation of acceptable environmental parameters for the
display and storage of Egyptian mummies and parchment to optimize theirchemical and physical stability. In chapter 3, Nieves Valentín, research biologist
at the Instituto del Patrimonio Histórico Español in Madrid, describes the environmental requirements for controlling biodeterioration of organic materials thatare acted on by insects, fungi, and aerobic and anaerobic bacteria. Both Hansen
and Valentín continued their research after the 1987-89 project, and major
results of their extended investigations are included in these chapters.
Physical principles, the description and engineering details of the hermeticallysealed display and storage cases, are discussed in chapter 4. Mechanical drawings and lists of components and their suppliers are also included. In chapter 5,
Nasry Iskander, director of the Conservation Center at the Supreme Council of
Antiquities, presents his experience in producing twenty-seven GCI-designed
cases in Egypt using locally available materials. He also describes technicaldetails of the newly opened Royal Mummy Room at the Egyptian Museum.
As a result of the successful design of the case, many cultural institutions haveexpressed interest in using it for their environmentally sensitive collections. The
GCI has recently concluded two collaborative projects in which objects were successfully installed in hermetically sealed, inert-gas-filled display and storage
cases. Chapter 6 gives details of the project undertaken with the National Physical Laboratory in New Delhi, India, to fabricate two hermetically sealed display
cases for the original document of the Constitution of India, now displayed at
the Parliament House in New Delhi. Chapter 7 presents a collaborative project
to conserve the Egyptian mummy of a child at the Biblioteca-Museu Victor
Balaguer in Vilanova i la Geltrú, Spain. Working with the Biblioteca-Museu,
project participants included the Instituto del Patrimonio Histórico Español; theGetty Conservation Institute; and the Metode Company, an art conservationand installation firm in Barcelona. The conservation team designed a hermetically sealed, argon-filled display and storage case that was built in Spain.

xi

Editor's Acknowledgment
The editor would like to acknowledge Frank Lambert, professor emeritus at
Occidental College, for his significant contribution to the development of the
Getty Conservation Institute's hermetically sealed storage and display case, andfor his advice in the editing of this publication.

Prefacexii

Chapter 1

Conservation of
the Royal Mummy
Collection at theEgyptian Museum
Shin Maekawa

Organic materials in museums and collections are especially susceptible to deterioration caused by changes in humidity and temperature; attack by fungi,
bacteria, or insects; the effects of photo-oxidation; and damage from gaseousand particulate air pollutants commonly found in urban and industrialized areas.
The catastrophic damage inflicted by biological and microbiological attack on
cultural treasures is well known. The harmful effects of these processes are commonly observed on delicate feather objects; on historic parchment documents;
on mummified human remains; on biological specimens of rare or extinct
species; and even on stone, where blackening or discoloration occurs. Just as
well known is the fact that all such biological attack is accelerated by high relative humidity, which is a constant threat in an uncontrolled environment. Obviously, the deleterious effects of oxygen-dependent organisms such as insects,
fungi, and aerobic bacteria on organic cultural objects (Rust and Kennedy 1993;
Valentín and Preusser 1990; Valentín, Lindstrom, and Preusser 1990) would be
eliminated if the objects could be maintained in a nitrogen or other oxygen-freeatmosphere.
For some three thousand years, the remarkable skill of the ancient Egyptians inpreserving the bodies of their pharaohs and others was coupled with environmental conditions of dryness and extreme temperature stability in tombs in theValley of the Kings and the Valley of the Queens. These ancient techniques andenvironments resulted in superb conservation that provided an unparalleledbridge to the past, transporting the actual bodies of ancient rulers of Egypt andof some of their subjects into the future.
Relatively recently, the mummies in the Royal Mummy Collection were moved tosimple museum cases in the Egyptian Museum in Cairo, an exceptionally busy
metropolis with very few environmental regulations and all the disadvantages ofa commercial city. The air is heavily polluted with oxidants as well as with particulate matter from automotive emissions, both of which are particularly
deleterious to organic materials. The concentration of sand and dust particles issignificantly high in the city because it is surrounded by a large desert. Moreover, the museum, because of its proximity to the Nile River, is much morehumid at night and in the early morning hours than are the Valley of the Kings
and the Valley of the Queens in the Egyptian desert. In addition, the museum, ahundred-year-old massive sandstone building, has neither air conditioning tocontrol the temperature and humidity nor air filters to remove particles of dieselsoot and other types of particulates and dust. It relies solely on open-window
ventilation for control of the indoor climate. These environmental conditions—
together with the large numbers of visitors to the world-famous museum, which
also affects the microclimate within it—constitute a serious hazard to the continued preservation of the royal mummies and other sensitive collections.
In September 1976, the mummy of Ramses II, from the Royal Mummy Collection at the Egyptian Museum, was sent to Paris for conservation treatment at the
Musée de I'Homme. After extensive documentation of the mummy and its condition, the infestation of Daedalea biennis Fries, a fungal species, was identified
as the major cause of the deterioration. During the conservation work that
followed, the mummy was placed in a custom-designed display case equippedwith a special ventilator and was sterilized with gamma-ray radiation using
cobalt-60. The mummy was flown back to Cairo in May 1978 and has been
kept in the case since the treatment. Conservators at the Supreme Council of
Antiquities have seen some color changes and have expressed their concern
about possible alteration of genetic information in the mummy that may haveresulted from its treatment (Nakhla and Iskander 1989).
In 1980, then-President Anwar el-Sadat closed the Egyptian Museum's Royal
Mummy Room, which housed the mummified remains of twenty-seven kings1and queens of ancient Egypt, for religious reasons. The world's best collection of
Egyptian mummies, which had been one of the most popular tourist attractionsin Egypt, was removed from display. The mummies were stored in a sealed roomon the museum's second floor under less than suitable environmental conditions.
Sadat's decision was later reversed, and the Egyptian Antiquities Organization(now named the Supreme Council of Antiquities) started to plan an improved
display of the mummy collection.
Thus it was that, in 1985, the Getty Conservation Institute was first approachedby the Egyptian Antiquities Organization (EAO) with concerns about alleviating
threats to the state of the royal mummies. It was the specific request of EAO
officials not only that the mummies be protected from harmful environmental
effects by a newly designed case, but that the case be both technically effective
and visually superior for the display of mummies. In other words, the caseshould be both safe for storage and aesthetically acceptable for viewing byvisitors.
In 1987, an agreement was signed by the EAO and the GCI for developing adisplay and storage case. The GCI was to be primarily responsible for design,
construction, and testing. The EAO was to document the mummies and restore
them to a state suitable for exhibition, as well as to investigate the microbiologyof the mummies, of their wrappings and cases, and of the exhibition room
environment. It was specified that the case should maintain a microenvironment
characterized by an inert-gas atmosphere and a stable relative humidity.
A number of requirements for the display and storage case were defined by the
GCI at the beginning of the project; these requirements would enable the projected case to have wider applications than that of protecting mummies: thepreservation of every kind of organic artifact by means of a controlled microenvironment in any museum in the world, including those with limited funds forcomplex cases.
However, past attempts to develop display cases or storage units that used anitrogen atmosphere and a controlled relative humidity either were extremely
expensive or required considerable maintenance or monitoring of gas-flowequipment. Additional problems have always arisen when mechanical orelectrical devices were attached to a case for humidity control. Accordingly, the
GCI undertook the design and construction of a hermetically sealed case that
could be filled with nitrogen or another inert gas and left unattended for an
extended period. In the inert microenvironment of such a case, freedom fromthe possibility of aerobic biological harm to an artifact could be achieved. Costand manufacturability were important constraints on research and development.
It was believed that the final product must be as inexpensive as possible, meeting the stated goals at relatively low capital cost and with minimal maintenance.
Finally, highly specialized tools or machines should not be necessary to build it.
In summary,• the cases should not be dependent on any mechanical or electrical systems;• they should require little maintenance, no more often than every two years;• it should be possible to manufacture and test the cases in developing
countries; and• the cost per case should be kept as low as possible.

Project Development
The work plan for the project included two major areas of research: first, toestablish ideal display and storage conditions for the mummies; second, todevelop hardware that could maintain such conditions. The factors studied were
the selection of an inert gas, the allowable level of oxygen, and optimal levels ofChapter 12relative humidity, temperature, and illumination. The design of hardware
proceeded parallel with research on storage conditions.

Proposed Storage Conditions
Research on the environmental parameters affecting the chemical and physicalstability of proteinaceous materials such as mummified tissues and parchment
was conducted by Eric Hansen at the GCI. Nieves Valentín, a research biologist
at the Instituto del Patrimonio Histórico Español in Madrid, carried out researchon the efficacy of nitrogen atmospheres for controlling biological and microbiological activities on mummified tissues and parchment between 1987 and 1989,
while working at the GCI as a research fellow. Valentín continued this researchon her return to Madrid.
The following recommendations are based on these research projects and literature reviews. An oxygen-reduced inert atmosphere of nitrogen at low relative
humidity suppresses both biological activity and oxidation in proteinaceous
material. Studies have shown the complete eradication of all stages of major
museum pests and significantly reduced microbiological activities where theoxygen concentration was maintained at less than 0.1 %. Clearly, the optimal
oxygen level is zero; in reality, however, this is impractical, so it should be kept
as close to zero as possible.

An ideal temperature range for the preservation of organic material is 10-15 °C.
A lower temperature reduces reaction rates in general and specifically the denaturing of collagen, the major constituent of mummy skin. In a closed microenvironment, relative humidity fluctuations depend on temperature fluctuations.
Lower temperature levels are desirable only if they do not increase humidity
variation. Furthermore, other museological considerations, such as human comfort, make low temperatures undesirable in display and storage rooms. However,
it is preferable to keep the temperature as constant and as low as possible.
An ideal relative humidity (RH) level is 30-50%. Values below 25% RH should
be avoided owing to the possibility of permanent deformation arising from irreversible dehydration of proteinaceous material. As demonstrated by research at
the GCI, microbiological activity on mummified tissue and parchment samples
was significantly reduced in the nitrogen microenvironment when the relative
humidity was below 50% RH. To remove oxygen that may leak into a case containing an inert gas, it is useful to add chemical substances—so-called oxygen
absorbers—that react with oxygen. Most oxygen absorbers require moderatelevels of moisture to react with oxygen. Reaction rates of the absorber called
Ageless decreased considerably after it had been in a 33% RH atmosphere for ayear; therefore, the higher level of about 45% RH is preferable if an oxygen
absorber is used.
The spectral distribution of the light reaching an object should be restricted to
the longest wavelengths that allow an acceptable appearance without any color
cast. Restricting light wavelength as close as possible to a 400 nm cutoff isaccomplished through the use of ultraviolet and possibly violet filters, theproper choice of an illuminant, or a combination of the two. The intensity of
the lighting should be limited to less than 100 lux for sensitive organic materials.

Display and Storage Case Design and Fabrication
A hermetically sealed display case for maintaining an inert-gas atmosphere waschosen over a continuous purging system, for the obvious reasons of the simplicity of the concept and the low maintenance required. The fabricated case consists of a display section, a bellows concealed below the display section, and aConservation of the Royal Mummy Collection

3

rigid base support system. The pressure-free condition of the case, despite atmospheric pressure changes, is achieved by inflation and deflation of the bellows
attached to the display section; this allows light construction of its hermetic seal.
The temperature-induced volume changes of the case's gas are similarly automatically adjusted by the inflation and deflation of the bellows. The case is filledwith humidity-conditioned nitrogen, is hermetically sealed from the surrounding
atmosphere, and is monitored for oxygen content and relative humidity without
needing to be opened (Fig. 1.1). Because of the extremely low leak rate of oxygen into the case, when it is initially filled with nitrogen, less than 2% oxygen
will be present after ten years. If packets of an oxygen absorber are placed in thecase, many additional years may elapse before the 2% oxygen level is exceeded.
A relative humidity buffering material, silica gel, which has been conditioned at
the selected humidity, is put in the case to provide a constant relative humidity
to compensate for temperature variation and any moisture from the oxygen
absorber or the displayed object.

Once the conceptual design was completed, a one-fifth scale model of the case
was fabricated at the machine shop of the GCI and shipped to the EAO for
approval. Detailed mechanical design and fabrication of a full-size prototype
case (1000 I volume) were contracted to Lightsense Corp., Laguna Beach, Calif.
The case was rigorously tested and various improvements in its design were
implemented at the GCI.
The presentation of the project report and the installation of the prototype hermetically sealed display and storage case to the EAO were made at the EgyptianMuseum in May 1989. The performance of the case was evaluated in situ fora period of two years in a non-air-conditioned room on the second floor of
the museum, which was proposed for the permanent exhibition of the royalmummies. The oxygen leak rate of the case, approximately 20 ppm per day, wasacceptable to both the EAO and the GCI.
Subsequently, additional design improvements for both better performance andsimpler fabrication were made at the GCI and forwarded to the EAO for its production of cases for the royal mummies. Some of the cases' components that the
EAO was unable to obtain in Egypt were identified, and the necessary quantityof the components to build twenty-seven cases was donated to the EAO by the
GCI. In addition to the aforementioned items, a set of aluminum extrusions for

Figure 1.1
Photograph of the nitrogen-filled, hermetically sealed display and storage case developed during the collaborative project topreserve the Royal Mummy Collection at
the Egyptian Museum in Cairo. Photo by
T. Moon.

Chapter 1

4

fabricating one complete case was given to the EAO for its first case. Productionof that case was carried out by the Supreme Council of Antiquities for its Royal
Mummy Collection in the Egyptian Museum in Cairo. Fabrication of other cases
was conducted in close consultation with the GCI until 1995. Eleven of the royalmummies were placed in the GCI-designed cases (the prototype case and ten
Egyptian-built cases), and the new Royal Mummy Room, which is climatecontrolled, was offically opened to the public in March 1994. As of December
1996, the Supreme Council of Antiquities had completed the assembly offifteen cases.

Acknowledgments
Frank Preusser, then-director of the Scientific Program at the GCI, managed the
project between 1987 and 1989; Neville Agnew, now group director, Information and Communications, at the GCI, assumed its management after that date.
GCI consultant Frank Lambert provided significant contributions to the testingand improvement of the case, as well as research on the Ageless oxygen
absorber. Steven Weintraub, then head of conservation processes at the GCI,
and George Rogers, then senior research fellow at the GCI, provided input
during the initial stage of the case design.

References
Nakhla, Shawky, and Nasry Iskander
1989

Conversation with the author.
Rust, M., and J. Kennedy
1993
The feasibility of using modified atmospheres to control insect pests in museums. Report, GCI Scientific Program, March.

Valentín, N., and F. Preusser
1990
Nitrogen for biodeterioration control on museum collections. In Biodeterioration
Research 3: Mycotoxins, Biotoxins, Wood Decay, Air Quality, Cultural Properties, General Biodeterioration, and Degradation, ed. Gerald C. Llewellyn andCharles E. O'Rear. New York: Plenum Press.

Valentín, N., M. Lindstrom, and F. Preusser
1990
Microbial control by low oxygen and low relative humidity environments.
Studies in Conservation 35:222-30.

Conservation of the Royal Mummy Collection

5

Conservation of the Royal Mummy Collection

6

Chapter 2

Protection of
Objects from
Environmental
Deterioration by
Reducing Their
Exposure to
OxygenEric F. Hansen

Robert Feller has stated, "The deterioration of organic substances through theirreaction with the practically unlimited supply of oxygen in the atmosphere is afundamental consideration of preservation science" (Feller 1976:287). Technicaladvances, as described in chapter 1, make it practical to build museum cases that
virtually exclude oxygen. Thus, objects that deteriorate in the presence of oxygen can be better preserved if displayed or stored in such cases.
This chapter discusses the effect of decreasing oxygen in the environments ofartistic or historic works. It will be shown, for the primarily proteinaceous materials used in the examples, that reducing the amount of oxygen around them willdiminish deterioration.

The past applications of low-oxygen environments in conservation are briefly
reviewed here, followed by a discussion of the general effects of lowering oxygen concentration. Specific examples are presented to show the difficulties
encountered in determining the beneficial effects for inhomogeneous and aged
materials. This latter discussion emphasizes that individual factors must be independently considered for specific objects and collections. The requisite oxygen
concentration, along with the relative humidity set point and allowable fluctuations, often represents a compromise rather than adherence to a strict, quotable
number.

Previous Applications
The most quoted early investigation of a low-oxygen environment for preservation purposes is the Russell and Abney Report of 1888 (Brommelle 1964),"Action of Light on Water Colors." There was concern over the fading of watercolor paintings in the South Kensington Museum and the National Gallery in
London. Various light sources (sunlight, gaslight, and incandescent light) wereavailable, but their individual effects on the fading of watercolors were notknown. This situation provided the impetus for a study of the fading of artists'colors used at that time.
Russell and Abney concluded that the presence of moisture and oxygen wasnecessary for a change to occur, indicating that many colorants found in thewatercolors they studied would fade less when exposed to light in vacuo. Thesefindings prompted the design of an airtight vacuum container for oil paintings
and watercolors, which was patented in 1893.
Kuhn (1968) demonstrated that improved protection for some light-sensitive
artists' materials (dyes and pigments) could be attained by replacing air withnitrogen. A design was suggested for a museum case in which the concentrationof oxygen is kept very low by maintaining a flow of nitrogen into it, thus creating a positive pressure. According to Kuhn, this method avoids many of the
problems involved in the design of seals for a case in vacuo or with static control
of a nitrogen atmosphere. It also allows humidification of the nitrogen, which isusually essential for organic materials. Kuhn also found that rates of fading
decreased at lower levels of relative humidity and temperature, but not as dramatically as with the exclusion of oxygen.

In addition to the benefits of an anoxic environment for retarding the fading ofcolorants, there have been applications for parchment (collagen); paper (cellulose); and, to a much lesser extent, metals. The 1951 report of the National
Bureau of Standards (NBS) on the required storage conditions for the Charters ofFreedom of the United States (the Declaration of Independence and the Constitution) provides an important presentation of the benefits of an inert atmosphere for classes of objects whose cultural value warrants the extra expense
involved in their preservation. This report was based in part on studies con7

ducted previously at the NBS on the effects of temperature and oxygen on thedeterioration of leather (Kanagy 1940). The parchment documents were stored
under an inert atmosphere of helium, humidified to 25% RH.
In addition to the Charters of Freedom, the handwritten preliminary copy, on
paper, of Abraham Lincoln's Emancipation Proclamation is stored in a doublechambered glass-and-aluminum capsule under nitrogen (Preservation Capsule1968), as are the twenty-nine sheets of the Constitution of Puerto Rico
(Passaglia, Brown, and Dickens 1980). It has been reported that the linen Shroudof Turin (a cellulosic) is preserved rolled in silk, within a silver-bound reliquary ina nitrogen atmosphere (Weaver 1980). An inert-gas atmosphere has also beensuggested, and implemented, for the storage of mummified remains of humans
and animals (David 1986). This method was used for Egyptian mummies at the
University of Turin but was found to be ineffective if the mummies alreadyshowed extensive signs of deterioration.
A low concentration of oxygen has also been suggested to preserve metals.
Airtight Plexiglas cases filled with nitrogen (probably dry) have been used (Salins
and France-Lanord 1943:26) to preserve iron plates from Merovingian belts.
Nitrogen-filled display cases were designed for the Musée Archéologique ofStrasbourg in an attempt to halt the noticeable deterioration of the iron in the
Merovingian helmet from Baldheim (France-Lanord 1949). Much later, out ofconcern for their preservation, sections of the gilded bronze Gates of Paradiseby Ghiberti were placed in Plexiglas containers filled with dry nitrogen in theMuseo Opificio del Pietre Dure in Florence (Bulst 1986).

Deterioration in the Presence of Oxygen
If the substance that makes up a museum object reacts with oxygen, the resulting oxidative chemical processes can cause physical changes, such as brittlenessand cracking; as well as chemical changes, such as color fading (Feller 1977,1994). Usually, however, museum objects are complex combinations of different
substances. Further, because there are many kinds of deterioration besides thosecaused by oxygen, it is not always possible to predict precisely what protection
from deterioration would be given to a particular object if it were placed in an
inert-gas environment such as nitrogen. The chemistry of oxygen's reactions
with several large classes of materials—cellulosics (paper, linen, cotton, andwood), proteins (parchment and vellum, skin of mummies), and colorants—is
now sufficiently well known, however, to allow useful general predictions about
how objects containing or composed of these materials will survive in nitrogenrather than in air.
Fairly pure cellulose, such as that found in acid-washed Whatman filter paper, is
not affected by oxygen in the absence of light; the reactions are very slow atambient temperatures (Zou etal. 1994; Heuser 1944:481, 487). However, ultraviolet radiation striking cellulose in oxygen degrades (breaks) some of the long
chains of atoms that are found in cellulose and causes brittleness and loss offiber strength, depending on the amount of ultraviolet exposure (Whitmore andBogaard 1995) and on the concentration of oxygen in the environment (Stillings
and Van Nostrand 1944). This photolytic oxidation of cellulose makes it more
susceptible to later nonphotolytic degradation: test samples that have been
exposed to ultraviolet, when heated in the dark in air in an 80 °C oven, degrade
more rapidly than control samples that have never been irradiated. Therefore,
degradation is probable over centuries in air at ordinary temperatures andhumidities if an object containing cellulose has been exposed at some time tolight rich in ultraviolet.
Chapter 2

8In summary, it is clear that removal of oxygen will hinder development of brittleness and loss of fiber strength in pure non-acidic cellulosics. This conclusion
should not be generalized to all objects containing cellulose, such as paper,
cotton, linen, or wood. For example, lower grade papers containing lignin—or anumber of other substances introduced in processing—may be even more susceptible to light-induced damage, even in the absence of oxygen (Leary 1967).
And, as is well known, the presence of very small amounts of acid in cellulose orcellulose objects, especially at high humidities, causes hydrolytic degradationand this process also leads to loss of strength in fibers. Therefore, a nitrogen
atmosphere, though helpful in reducing oxidative damage, is not a universal
cure for all modes of cellulose deterioration.
Proteins typically constitute parts of historic and of art objects. Collagen is theprincipal protein of the skin of mummies and of animal skins, and thus is the
major substituent of parchment (from goats and sheep) and of vellum (fromlambs, kids, and calves). Sobel and coworkers (1968) have shown that collagenreacts slowly with oxygen to form a variety of compounds; Sobel and Hansen(1989) have extended this work to suggest that the amount of change in a protein could be roughly related to its age.
Obviously, then, an oxygen-free environment would preserve proteinaceous
materials such as parchment and mummified remains by greatly reducing theirrates of deterioration by oxygen. Insofar as similar changes arising from reaction
with oxygen are reported in the proteins of silk (fibroin and sericin), objects containing these materials could also be better preserved by placement in oxygenfree environments (Hansen and Sobel 1994).
Colorants—dyes and pigments in watercolors—have been mentioned in thischapter as subjects of the earliest studies related to conservation using a
reduced-oxygen environment. Organic dyes show a great range of fading
behavior under the influence of light; those most prone to fading are almost as
fugitive in sunlight as the term suggests. The rate of fading of many dyes innitrogen atmospheres decreased even faster than the oxygen level decreased atlower and lower oxygen concentrations (Arney, Jacobs, and Newman 1979).
However, this determination of the increase in life expectancy of many colorants
in nitrogen was accompanied by the warning that a minority of colorants arereported to fade more rapidly in the absence of oxygen than in its presence.
A similar caution has been challenged: Kenjo (1980) stated that sienna (whichcontains iron oxide) and litharge (a lead oxide) fade in low-oxygen conditions,
but Koestler and coworkers (1993) determined more recently that no such fading in nitrogen was observable by two skilled paintings conservators. Kenjo also
reported that red vermilion (mercuric sulfide) darkened when oxygen wasremoved in his fading tests. However, this is undoubtedly the result of mercuric
sulfide's well-known crystal-structure change to black cinnabarite under the
influence of bright light, not an effect of lack of oxygen (Feller 1967).

Case Studies
Parchment

Parchment is a writing material whose distinctive characteristics are producedby drying dehaired animal skin under tension. Its major constituent is insoluble

collagen, which constitutes about 95% of defatted, dehaired skin.
Atmospheric oxygen reacts with collagen over time, causing cross-linking or
chemical modification of several amino acids in the protein chains (Sobel andHansen 1989). The changes resulting from oxidation depend on the way theProtection from Environmental Deterioration9

parchment was processed, as well as on the residual fats and also the type andamount of additives, such as softening agents.
In 1951, the National Bureau of Standards reported its conclusions on "the bestmeans of preserving the original copies of the Declaration of Independence andthe Constitution of the United States" in response to a request from the Libraryof Congress (NBS 1951). They recognized that an inert gas would eliminate
destructive components in the atmosphere, oxygen in particular. Further, thepresence of either too much or too little moisture could contribute to the deterioration of parchment. Finally, a suitable filter should be found that would eliminate the damaging effects of light radiation. Based on a number of studies of thestability of collagen and leather (also processed from skin), they suggested using
a display case containing a helium atmosphere humidified to a relative humidityof 25%. A laminated plastic-and-glass wall would filter out both the ultraviolet
and some of the blue light. The Charters of Freedom were later examined by apanel of scientists and conservators in 1982 without being removed from thecase (Calmes 1985). No evidence of deterioration beyond that observed at thetime of encasement could be documented through comparison of photographs.
In a subsequent study, Sobel and Ajie (1992) extracted fragments of Dead Sea
Scroll parchments for collagen and subjected the extracts to amino acid analysis
by high-performance liquid chromatography. In modern parchment samples,
90% or more of the protein could be extracted in hot aqueous solution. In contrast, because of oxidative cross-linking in ancient specimens, only 70% orless was extractable. When the soluble extracts were analyzed, the quantities of tyrosine, histidine, and methionine were found to be reduced in theextracts from ancient parchment. In addition, an oxidation product of tyrosine,
di-tyrosine, was detected. Because these amino acids are those that are expected
to be affected by oxygen, Sobel and Ajie concluded that "they seem to be
reduced . . . as a result of an oxygen effect."
Further studies were conducted by the GCI to support recommendations to theIsrael Museum on the optimum environmental conditions for the display andstorage of the Dead Sea Scrolls. The effects of relative humidity were consideredin addition to those of atmospheric oxygen. Hansen and coworkers (1992)
investigated the effects of various relative humidities on some physical properties of calfskin parchment (vellum). Standard samples were subjected to tensile
testing after equilibration at various relative humidities between 11 % and 60%.
In further tests, samples were restrained at a specific length, and the force thatdeveloped in them was measured as the relative humidity was lowered.
Brittleness was observed below 11 % RH, and it was found that about 25% RH
was the lowest relative humidity that could be tolerated without inducing large
stresses in the material. Based on these results, the gelatination that may be promoted at humidity levels above 40%, and the biodeterioration of parchment at
higher humidity levels (Valentín, Lindstrom, and Preusser 1990), Hansen andcoworkers (1992) suggested a relative humidity of 30% for the optimum environment of objects derived from skin. These conclusions do not differ significantly from those proposed by the NBS in 1951 for the Charters of Freedom.
Another very important consideration is the extent of deterioration of an object
that is ancient, such as the two-thousand-year-old Dead Sea Scrolls. Several
studies have indicated that much of the collagen in the Dead Sea Scrolls has
been altered (Burton, Poole, and Reed 1959; Derrick 1992; Weiner et al. 1980).
Because of the particular cultural importance of such objects as the scrolls, factors providing the longest-term durability (relative humidities lower than 50%)
may outweigh immediate aesthetic effects. These include possible curling or curvature of a document (Schilling and Ginell 1993), along with the extra care in
Chapter 2

10handling that is needed for a more brittle material. Thus, in addition to the
exclusion of oxygen, the provision of a stable relative humidity above 25% RH
and below 40% RH appears desirable.
Other considerations have not been fully studied, however, particularly theeffects of relative humidity on the physical stability or adhesion to the parchment substrate of inks or colorants present in painted parchment manuscripts.
Recommendations for a relative humidity of 50% or higher may be suitable
for a particular situation in which pliability or other physical properties of parchment are the main concerns, rather than very long-term physical and chemical
stability.
The royal mummies at the Egyptian Museum
The mummification procedure in ancient Egypt changed over the centuries.
Therefore, a general perspective needed to be adopted to determine suitableenvironmental conditions for the royal mummies at the Egyptian Museum in
Cairo. A primary factor in the present state of preservation of the mummified
remains of the pharaohs is the original success of the mummification process.
Although a mummy may be wrapped and/or stuffed with linen or cotton andcoated with resins, the object consists mainly of the intentionally desiccatedremains of a human body; and conditions that are optimal for proteinaceous
materials (such as collagen in skin, keratin in hair, etc.) are given the greatest
consideration.
The most important function of an inert atmosphere for the royal mummies is
the suppression of biological activity, particularly because no other desirable
fumigant or sterilant system has been proposed or shown to be successful (seethe discussion of gamma-ray exposure in chapter 3, page 17). Furthermore,because of the collagen and other proteinaceous materials present that will be
modified by oxygen over time, an inert atmosphere is also desirable for the same
reasons given for parchment.
The preservation of mummified material is highly dependent on the successful
removal of moisture before deterioration becomes pronounced. Thus, rehydration of mummies should be avoided because higher relative humidities promote
not only gelatination but also hydrolysis, which results in a reduction of themolecular weight of proteins. Barraco (1977) found such a change in molecularweight in protein extracted from the tissues of an Egyptian mummy (Nakht Rom I)
by comparison with protein from freshly autopsied human skeletal muscle.
Hansen (1989) found that the water-absorption curves of samples from a varietyof Egyptian mummy tissues (skin and skeletal muscle) were similar to the waterabsorption curves of modern parchment. The percentage water uptake was thesame after exposure to a higher relative humidity following equilibration at alower relative humidity. In addition, the force developing in mummified skin at a
restrained gauge length was similar to that in modern parchment when the relative humidity was lowered. The partially rehydrated mummified tissue developeda large force of contraction when exposed to relative humidities below 20%.
These data, although restricted to a few samples of mummified tissue from asingle historical time period, support a relative humidity recommendation formummified human remains similar to that for parchment.

Conclusion
Although the majority of studies in the field of conservation involving an essentially oxygen-free environment have focused on the reduction of fading rates ofcolorants, implications also exist for museum cases designed to display imporProtection from Environmental Deterioration11

tant written documents on paper and parchment, and a variety of proteinaceous
objects. The Charters of Freedom of the United States of America, the Constitution of India, and mummified human remains such as those in the Royal Mummy
Collection of the Cairo Museum are prime examples.

Oxygen reacts with parchment (made from animal skin) and with some of thematerials present in mummies over long periods of time; it changes their chemical composition and, subsequently, their physical properties. Thus, the preservation of these objects is aided by excluding oxygen from museum cases in which
they are displayed or stored.
The chemical complexity of aged natural products does not allow a specific"number" or quantifiable oxygen concentration to be stated for optimum preservation of these objects. However, a reduction of the oxygen concentration to thelowest that can be achieved, preferably below 1000 ppm, is the most prudent
course.
In the specific case of materials containing collagen, a range of 25-40% RH has
been suggested. Below this level, the chemical and physical stability of collagenis affected. The desirable set point of relative humidity above 25% depends
on whether conditions are intended for long-term storage or for short-term
handling or display.

References
Arney, J. S., A. J. Jacobs, and R. Newman
1979

The influence of oxygen on the fading of organic colorants. Journal of theAmerican Institute for Conservation 18:108-17.
Barraco, R. A.
1977

Analysis of protein extract. CMA Journal 117:474.
Brommelle, N. S.
1964

The Russell and Abney Report on the action of light on watercolors. Studies inConservation 9(4):140-51.
Bulst, W. A.
1986
Ausstellungen: L'oro del Ghiberti. Restauri alia porta del Paradiso, Florenz, 7.
Dezember 1985-2. Februar 1986. [Exhibitions: Ghiberti's gold. Restorations
on the door of Paradise, Florence, 7 December 1985-2 February 1986.]
Kunstchronik 39(4): 125-26.

Burton, D. M. B. E., J. B. Poole, and R. Reed1959

A new approach to the dating of the Dead Sea Scrolls. Nature 164:533-34.

Calmes, A.
1985
Charters of Freedom of the United States. Museum 146:99-101.

David, A. E.
1986

Conservation of mummified Egyptian remains. In Science in Egyptology.
Manchester, England: Manchester University Press.
Chapter 2

12Derrick, M.
1992

Evaluation of the state of degradation of Dead Sea Scroll samples using FT-IR
spectroscopy. American Institute for Conservation Book and Paper Group
Annual 10:49-65.
Feller, Robert L.
1967

Studies on the darkening of vermilion by light. In Report and Studies in the
History of Art 1967, 99-111. Washington, D.C.: National Gallery of Art.
1976
The deterioration of organic substances and the analysis of paints and varnishes.
In Preservation and Conservation: Principles and Practices, ed. Sharon Timmons,287-99. Washington, D.C.: Smithsonian Institution Press.

1977
Stages in the deterioration of organic materials. In Preservation of Paper andTextiles of Historic and Artistic Value, ed. J. C. Williams, 314-35. Advances in
Chemistry Series, no. 164. Washington, D.C.: American Chemical Society.
1994
Accelerated Aging: Photochemical and Thermal Aspects. Marina del Key, Calif.:
Getty Conservation Institute.

France-Lanord, A.
1949
La conservation du casque Merovingien de Baldheim. Cahiers d'Archeologie etd'Histoire d'Alsace 130:277-80.

Hansen, E. F.
1989

Initial recommendations for the display conditions of the Royal Mummies of the
Cairo Museum. Internal report, Getty Conservation Institute, Marina del Key,
Calif.
Hansen, E. F., S. N. Lee, and H. Sobel
1992

The effects of relative humidity on some physical properties of modern vellum:
Implications for the optimum relative humidity for the display and storage ofparchment. Journal of the American Institute for Conservation 31(3):325-42.
Hansen, E. F., and H. Sobel
1994

The deterioration and preservation of silk. The Textile Specialty Group
Postprints, American Institute for Conservation 20th Annual Meeting, Buffalo,
New York, June 1992, 14-30. Washington, D.C.: AIC.
Heuser, Emil
1944

The Chemistry of Cellulose. New York: John Wiley and Sons.
Kanagy, J. R.
1940

Effect of oxygen concentration and moisture on the stability of leather atelevated temperatures. Journal of Research of the National Bureau of Standards
25:149.
Protection from Environmental Deterioration

13

Kenjo, T.
1980
Studies on the long-term conservation of cultural properties (part 1). 2. Effects
of different concentrations of oxygen on pigments used for cultural properties.
Scientific Papers on Japanese Antiquities and Art Crafts 25:103-07.
Koestler, R., E. Parreira, E. Santoro, and P. Noble
1993

Visual effects of selected biocides on easel painting materials. Studies in Conservation 38:265-73.
Kuhn, Herman
1968

The effect of oxygen, relative humidity and temperature on the fading rate ofwatercolours. Reduced light damage in a nitrogen atmosphere. In Contributions
to the London Conference on Museum Climatology, 18-23 September 1967, ed.
Garry Thomson, 79-85. London: International Institute for Conservation ofHistoric and Artistic Works.
Leary, G. J.
1967
The yellowing of wood by light. TAPPI 50(1):17-19.

National Bureau of Standards (NBS)
1951
Circular 505, Preservation of the Declaration of Independence and the Constitution of the United States. Washington, D.C.: NBS.
Passaglia, E., D. Brown, and Brian Dickens
1980
The Preservation of the Constitution of Puerto Rico. Washington, D.C.: NBS.

Preservation Capsule
1968
Manuscripts 20(2):56-60.

Salins, E.r and A. France-Lanord
1943

Le Fer à I'Epoque Merovengienne. Paris: Librairie Orientaliste Paul Geuthner.
Schilling, M. R.r and W. S. Ginell
1993

The effects of relative humidity changes on Dead Sea Scrolls parchment samples.
In ICOM Committee for Conservaton 10th Triennial Meeting, Washington, D.C.,
USA, 22-27 August 1993, Preprints, vol. 1, ed. J. Bridgland and J. Hill, 50-56.
Paris: ICOM Committee for Conservation.
Sobel, H., and H. Ajie
1992

Modification of amino acids of Dead Sea Scroll parchments. Free Radical Biology
and Medicine 13:701-2.
Sobel, H., and E. F. Hansen
1989

Environmentally produced changes in historic proteins. A: Collagen. Text of aposter presented at the Third Annual Symposium of the Protein Society, Seattle,
Wash.
Chapter 2

14

Sobel, H., M. J. Hewlett, F. Hariri, and R. S. Pogrund
1968

Skin composition following exposure of mice to a hyperbaric oxygen-nitrogenmixture. Proceedings of the Society for Experimental Biology and Medicine 129:
89-91.
Stillings, R. A., and R. J. Van Nostrand
1944
The action of ultraviolet light upon cellulose: I. Irradiation effects. II. Postirradiation effects. Journal of the American Chemical Society 66:753-60.

Valentín, N., M. Lindstrom, and F. Preusser
1990
Microbial control by low oxygen and low relative humidity environment. Studies
in Conservation 35:222-30.

Weaver, K. F.
1980
The mystery of the shroud. National Geographic 157(6):730-53.

Weiner, S., Z. Kustanovish, E. Gil-Av, and W. Traub1980

Dead Sea Scroll parchments: Unfolding of the collagen molecules and racemization of aspartic acid. Nature 287:820-24.
Whitmore, P. M., and J. Bogaard
1995

The effect of oxidation on the subsequent oven aging of filter paper. Restaurator
16:10-30.
Zou, X., N. Gurnagul, T. Uesaka, and J. Bouchard
1994

Accelerated aging of papers of pure cellulose: mechanism of cellulose degradation and paper embrittlement. Polymer Degradation and Stability 43:393-402.

Protection from Environmental Deterioration

15

Protection from Environmental Deterioration

16

Chapter 3

Preservation ofHistoric Materials
by Using Inert
Gases forBiodeterioration
Control
Nieves Valentín

This chapter is concerned with solving two problems related to biodeterioration:
insect infestation and the growth of microorganisms. Either can be devastating
to historic or prized objects. Both can be counteracted by the use of an inert gas
such as nitrogen or argon and control of the relative humidity.
For many years, grains and other food products have been protected from
insects and rodents by storing them in low-oxygen environments, primarily
nitrogen (Bailey and Banks 1980:101-18; Nakamura and Hoshino 1983; Navarro
and Jay 1987; Fleurat-Lessard 1990; Donahaye 1990; Smith and Newton 1991).
Nitrogen does not kill insects directly; it simply prevents an undesirable pestfrom obtaining the oxygen it needs for continued life. Thus, nitrogen anoxia
does not kill as rapidly as the toxic gases that have conventionally been used.
However, the common fumigants for treating art and cultural objects have been
methyl bromide, ethylene oxide, and Vikane (sulfuryl fluoride). Each of these
poses serious threats to the collections being treated, as well as creating potential hazards for the conservators responsible for the procedure (Florian 1988).
Fungal and bacterial attacks on historic objects can result in unsightly blotches
ranging from whitish through green or reddish brown to black, as well as actual
destruction of the fine structures of their surfaces. Older methods of killing fungior bacteria with solutions of toxic cresols (ortophenyl phenol and sodium salt,
pentachlorophenol and sodium salt p-chloro-m-cresol, and thymol) or tetralkylammonium salts are now in disfavor for clear reasons of possible harm to theobjects as well as to the conservators. Delicate vacuuming of the affected area
to remove the "bloom" of fungus and the application of alcohol are a preferred
procedure, although, because the alcohol evaporates relatively rapidly, the transient nature of its protection is a disadvantage. Gamma radiation has also beenused for sterilization of cultural objects, such as paper and mummies (Pääbo,Gifford, and Wilson 1988; Hutchinson 1985), but it can harm the materials being
treated, requires truly expert supervision for safety and effectiveness, and iscostly.

Although nitrogen had been employed in conservation for various purposes, its
use for insect disinfestation was not widespread at the time of the author's initial
work in 1987 (Valentín 1989). There is good evidence that a nitrogen atmosphere retards the fading of many watercolors and organic colors subject tooxidation (Valentín, Algueró, and Martin de Hijas 1992; Koestler et al. 1993; seechapter 2 for references to the minority of colors that fade in nitrogen, and thecorrection to Kenjo 1980).

In 1987, a research program whose goal was preventive conservation ofoxygen-sensitive museum objects from biodeterioration was begun at the Getty
Conservation Institute, using the low-oxygen environments of nitrogen atmospheres. From 1989 to the present, this research has continued at the Institutodel Patrimonio Histórico Español (formerly the Instituto de Conservación yRestauración de Bienes Culturales [ICRBC]). It was intended to investigate(1) killing insects already present or those that would invade in the future and(2) controlling microbiological activity such as that of bacteria or fungi.

The Elimination of Insect Infestation in Museum Objects
The damage that can be inflicted on museum or library objects by insects isalmost as well known to the public as it is to conservators. Any householder withwoolen clothing knows how the feeding habits of clothes moths can ruin theappearance of a garment, just as individuals in warm climates are familiar withthe equally ubiquitous termites and their attacks on house structures. Most private owners of collections of historic books have seen holes in paper and parchment pages or evidence of attacks on leather bindings by insects. Of course, theproblem for a museum, with its unique objects, is far more serious. The depreda17

tions of insects must be halted, not merely controlled, for the preservation ofcultural treasures for future generations.
Initial experiments in attacking this serious problem were designed to determine
the efficacy of low-oxygen nitrogen atmospheres in killing a well-studied insect,
Drosophila melanogaster, and then to conduct a practical test by placing aninfested museum object in nitrogen under controlled environmental conditions.
For the Drosophila work, a large number of all of the insect's life forms—eggs,
larvae, pupae, and adults—were subjected to various combinations of temperature, RH, and length of exposure. Results showed complete insect mortality after
80 hours at 25 °C, 75% RH, and 0.5% oxygen (99.5% nitrogen). Afterward, apolychrome picture frame that was being actively attacked by Cryptotermes
brevis was successfully disinfested by exposure for fifteen days in the same
nitrogen atmosphere (0.5% oxygen) at 22 °C and 50% RH (Valentín andPreusser 1990).
Rust and Kennedy (1993) reported their in-depth entomological studies of nitrogen anoxia, which were carried out under the sponsorship of the GCI. They
examined a large sample population of all of the life forms of the ten species of
insects that are considered to be the most common museum pests in the UnitedStates and Canada. Using nitrogen-filled test chambers in which the oxygen
content was rigorously controlled at less than 0.1 %, they found that only
72 hours at 25.5 °C and 55% RH were required for a complete kill of mostdevelopmental stages of most species. However, 192 hours (eight days) wererequired for total mortality of all egg forms of Lasioderma serricorne (cigarette
beetle). Therefore, a minimal exposure of ten days in a 0.1 % oxygen-containing
nitrogen atmosphere (and 25 °C, 55% RH) is conservatively advisable to achieve
total insect anoxia in museum objects.
Conservators at other institutions have reported the success of nitrogen atmospheres in eradicating insects in historic objects (Gilberg 1991; Hanlon et al.
1993; Koestler 1992). After beginning work at the GCI, the author continued
these investigations at the ICRBC in Spain. Extensive evaluations were concluded
for eight different species of insects in all stages, using not only nitrogen atmospheres but argon and carbon dioxide (Valentín 1993) in widely varied types of
fumigation containers. Carbon dioxide was ineffective in eliminating the species
in the Cerambycidae, Anobiidae, Dermestidae, and Lyctidae; this would make itsuspect for use in treating any infested objects without a detailed entomologicalexamination to determine what insects were present. It was further established(Fig. 3.1) that for Anobium punctatum (furniture beetle), Attagenus piceus,
Hylotrupes bajulus (house longhorn beetle), Lasioderma serricorne, Lyctus brunneus, Nicobium castaneum, and Stegobium paniceum (drugstore beetle), a
shorter exposure time was required for complete mortality in argon than in nitrogen. However, using argon at shorter exposure times than used with nitrogen tokill insects in a museum piece would be unwise without expert entomologicalevaluation of the infesting species, a requirement that may be impossible forsome museums to meet and tedious for others. An important finding in the work
was that an increase in temperature in the anoxia container or chamber from
20 °C to 30 °C resulted in a marked decrease in the time required for complete
mortality.
Anoxia of Hylotrupes bajulus, Lasioderma serricorne, and Anobium punctatumat 40 °C required only one day in both argon and nitrogen, whereas at 20 °C,
the time required for anoxia of these three species in argon and nitrogen were,respectively, nineteen, eight, and six days; and nineteen, ten, and eight days
(Fig. 3.2). It is clear that a high temperature such as 40 °C may be inadvisable
for some museum objects. Nevertheless, for plant species collected from expeditions, such high temperatures are not only tolerable but useful in aiding their
Chapter18

Figure 3.1

Insect mortality using nitrogen

Exposure time (days)

Effect of temperature on the exposure timerequired to achieve a complete insect mortality at 40% RH and low-oxygen concentrationin nitrogen and argon atmospheres (<0.1%)
shown for (1) Hylotrupes bajulus, (2) Lasioderma serricorne, (3) Anobium punctatum,(4) Xestobium rufovillosum, (5) Lyctus brunneus, (6) Stegobium paniceum, (7) Nicobium
castaneum, and (8) Attagenus piceus.

Insect species

Exposure time (days)

Insect mortality using argon

Insect species
drying prior to storage. No physicochemical alterations, including color changes
on petals, were found in plants treated at 35-40 °C for five days (Valentín,
Algueró, and Martin de Hijas 1992). Thus, disinfestation and initial drying canbe carried out in one step under a nitrogen flow through an oven at 40 °C.

The Control of Fungal and Bacterial Growth on Museum Objects
Proteinaceous materials such as parchment, leather, and mummified tissues arehighly susceptible to aerobic fungal and bacterial and anaerobic bacterial
growth. Aerobic bacteria can damage both the surfaces and the lower layers ofthese materials with unpleasant stains, as do fungi with their visually disagreeable blotches of white, green, or dark-colored colonies that resemble efflorescence. Anaerobic bacteria produce proteolytic enzymes, which cause collagen
depolymerization and thus loss of an object's strength and even its integrity.
Anaerobic fungi are very infrequent in organic objects (Kowalik 1980). TherePreservation of Historic Materials

19

Argon treatment for insect elimination

Exposure time (days)

Figure 3.2
Effects of high temperature and argon andnitrogen atmospheres on the exposure timerequired to eradicate Lasioderma serricorne in
herbaria collections. Hylotrupes bajulus andAnobium punctatum were used as models.

Temperature, °C

Exposure time (days)

Nitrogen treatment for insect elimination

Temperature, °C

fore, the second objective of the GCI program that was begun in 1987 wasevaluation of the influence of RH and low-oxygen atmospheres on bacterial
growth, including anaerobes. The general procedures and conclusions are givenin the following sections.
Aerobic organisms

To find the effect of RH and low-oxygen atmospheres on fungal and bacterial growth, samples of microorganisms were isolated from the skin of athree-thousand-year-old mummy of an adult female that had been loaned to
the GCI by the Egyptian Antiquities Organization (EAO). Most microorganisms(Fig. 3.3) corresponded to Aspergillus niger, Aspergillus flavus, Penicillium
commune, Actinomyces sp., Bacillus sp., and Streptomyces sp., but anaerobic
types were also found and taken for testing.
Chapter 320

Figure 3.3
Fungal and bacterial contaminants isolated
from a three-thousand-year-old Egyptian
mummy of an adult female, treated withnatron.

Contamination in Egyptian mummy (adult)

The microbial samples were inoculated on clean parchment strips and exposed
to various combinations of RH (33%, 43%, 50%, 75%, 85%, and 100%) andoxygen concentrations (0.1%, 1%, 5%, and 20%) in nitrogen atmospheres.
Their growth rate was monitored by determining the radioactivity in the carbon
dioxide produced after about three days by the heterogeneous populationof fungi and bacteria growing on the parchment strips in the presence of
C-14-containing sodium lactate or succinate.
The biological activity of the microorganisms was retarded remarkably when theoxygen level was 1% or less and the RH was lower than 50%. As shown in
Figure 3.4, if the oxygen present in the nitrogen atmosphere was only 0.1%,
even at 50% RH there was essentially no increase in the amount of radioactive
carbon dioxide produced after about three days; that is, the number of microorganisms was unchanged from that time on. In fact, after only 10 hours of
exposure to 45% RH at the lowest oxygen level, this inhibition of growth wasnotable and was moving toward stabilization of the size of the colonies, asignificant control of biological activity.
It is not novel to find that lower-RH environments hinder the growth of microorganisms. Common fungi, including those cellulolytic species that are harmful
to paper and wooden museum objects, need an RH of over 80% for significant
growth (Gallo 1992). Only the xerophilic fungi, far rarer in cellulose or proteinaceous materials, can grow at 65% RH. Normal bacteria also require very highRH, about 90%, to grow best, with halophic bacteria a notable exception at
75% RH. Common yeasts multiply well at 88% RH. The lowest RH that istolerated for optimal microbial growth, 60%, has been reported for the
Saccharomyces rouxii yeast. However, the conservator should not conclude
that simply keeping objects in a display case at a given RH will insure inhibitionof the growth of harmful microorganisms. The hygroscopicity of the object's
material(s) and the specific moisture content of the support, and the surrounding environmental conditions, can contribute to the RH immediately at thesurface of an object and thus affect the microbial growth rate. However, the factthat a combination of a low-oxygen concentration in nitrogen atmospheres withcomparatively low RH completely stops the growth of microorganism colonies is
an important finding of this study (Fig. 3.5).
Anaerobic organisms
This phase of the research involved the use of small skin fragments from mummified remains, acquired from various museums in Spain, as well as noninvasive
samples obtained from an Egyptian mummy then being studied at the GCI. A
Preservation of Historic Materials

21

Effects of various relative humidities and oxygen concentrations on the biological activityof a heterogeneous population of microorganisms inoculated on parchment samples
and incubated for four weeks.

Counts 14C lactate (cpm × 100.000)

Figure 3.4

Effects of RH and O2 on microbialactivity at 85% RH

Counts 14C lactate (cpm × 100.000)

Incubation time (weeks)

Effects of RH and O2 on microbialactivity at 50% RH

Counts 14C lactate (cpm × 100.000)

Incubation time (days)

Effects of RH and O2 on microbialactivity at 33% RH

Incubation time

Chapter 3

22

Figure 3.5

Bacterial growth in mummy skin

Bacterial growth in mummy skin exposed
to various relative humidities and oxygen

Log bacteria by sample

concentration for nine weeks.

Percent O2

rapid method involving epifluorescence microscopy was employed to detectincreases in anaerobic as well as aerobic bacterial growth (Valentín 1990).
The procedure required a totally particulate-free solution of the fluorescent dye
acridine orange. This was obtained by passing the dissolved dye (250 mg perliter of deionized water) through a cellulose nitrate nucleopore membrane. Thenthe possibly contaminated proteinaceous materials that had been exposed todifferent RH conditions (33%, 40%, 75%, and 100%) at oxygen levels of 1 %and 20% were treated with the stain. The DMA and RNA of any viable or nonviable microbial cells on the sample fragments were characterized by theirfluorescence under epifluorescence microscopy. Both aerobes and anaerobes
were detected, and evaluation of their growth was made.
Even after nine weeks, there was high bacterial growth in samples that were
exposed to RH greater than 70%, despite the presence of only 0.1% oxygen in
the nitrogen atmosphere, a clear indication of the presence of anaerobes. However, just as with aerobic microorganisms, essentially zero growth of colonies
occurred when the RH was in the 33-40% range and the oxygen content of thenitrogen atmosphere was 0.1%. It should be emphasized that it has been demonstrated that exposure of proteinaceous materials to low humidities (in the
30-40% range) prevents significant alterations in the physico-chemical properties (Petushkova and Nikolaev 1983; Hansen, Lee, and Sobel 1992; seechapter 2).

Inert Gases for the Biodeterioration Control of Mummified
Remains: A Case Study BackgroundThe conservation of a contaminated mummy

To demonstrate the disinfestation process that would involve both an inert gas
with low oxygen content and a low RH, an Egyptian mummy of a five-year-old
child (Fig. 3.6) was selected for the treatment. The mummy had been on display
at the Biblioteca-Museu Victor Balaguer in Vilanova i la Geltrú, Spain, since1886, first in a succession of two wood-framed glass cases and then, from 1988
to 1992, in a marble-based unit whose glass superstructure was framed in metal.
Elegant as it was, it was far too leaky and thus allowed spores as well as considerable dust to enter. Further, the fluorescent light in its top was too intense andcaused photooxidation of cellulosic material close to it. The mummy, which had
rested on a cushion that retained moisture and dust, showed the visible presenceof fungus mycelia and stains produced by bacteria (Fig. 3.7). The mummy was
Preservation of Historic Materials

23

Figure 3.6

Egyptian mummy of a five-year-old childon display at the Biblioteca-Museu Victor
Balaguer in Vilanova i la Geltrú, Spain. The
mummy was treated with an argon
atmosphere.

wrapped and covered with polychrome papyri. The wraps showed high microbial
contamination and insect infestation, augmented by the condensation problemsof the display case, where it had been exhibited for four years. Microorganismsthat were isolated from the mummy, as shown in Figure 3.8, included Penicillium, Aspergillus, Ulodadium, Stachybotrys, Bacillus, Streptococcus, Actinomyces, Mucor, and Streptomyces. Dermestidae insects were found in the mummy'shead.
To control microbial growth and insect infestation, the mummy was laid on a
perforated acrylic support to allow atmospheric circulation around the body. The
mummy and support (Fig. 3.9) were then placed in a bag fabricated from a plastic that had a very low oxygen permeability (Fig. 3.10). Argon, humidified to an
RH of 40%, was purged to flow through the bag at the rate of one liter per
minute for six months to maintain the low-oxygen environment. Microbial
analyses were conducted throughout the treatment period. The comparative
results shown in Figure 3.11 indicate a decrease in fungal and bacterial growth
after only five weeks of using this dynamic flow system of inert gas treatment at
40% RH. At the end of a two-year period in argon, the mummy was installed in
Figure 3.7

Microbial contamination due to fungus mycelia and stains produced by bacteria on theunderside of the mummy shown in Fig. 3.6.

Chapter 324

Figure 3.8
Chart showing relative proportions of fungal
and bacterial contaminants isolated from thewrapping of the Egyptian mummy of a childshown in Fig. 3.6.

Contamination in Egyptian mummy (child)
Actinomyces
Bacillus
Penicillium
Aspergillus
Streptomyces
Mucor
Stachybotrys
Streptococcus
Ulocladium

Figure 3.9

Perforated Plexiglas support for the mummy
used during the argon treatment.

Figure 3.10

The mummy placed in a bag fabricatedfrom a plastic that had a very low oxygen
permeability.

Preservation of Historic Materials

25Microbial contamination

Figure 3.11

Chart showing decrease of microbial contamination in the Egyptian mummy of a child
exposed to the argon atmosphere at 40% RH

Microorganisms

and 20-23 °C for five weeks.

Colonies by sample

Treated mummy
Untreated mummya hermetically sealed case under an inert gas atmosphere to insure its long-termpreservation (Maekawa, Preusser, and Lambert 1992; see chapter 7).

Conclusion
Argon and nitrogen have been proven effective in killing all life forms ofmuseum insects by depriving them of oxygen (causing anoxia); if the oxygen
content of the inert gas is reduced to 0.1 %, argon works faster than nitrogen.
The required duration of exposure to this inert environment depends on theinsect species, life stage, oxygen content, type of inert gas, relative humidity,
and temperature. (Desiccation of the insects may be the cause of their death,resulting from water loss during hyperactivity while attempting to obtainsufficient oxygen.) Carbon dioxide has been found ineffective in killing Cerambycidae, Anobiidae, and Lyctidae. Increasing the temperature in the treatment
chamber from 20 °C to 30 °C markedly reduces the time required for a 100%
eradication. A permanent fumigation room, a portable commercial type of"bubble," or a plastic enclosure fabricated from an oxygen-impermeable film
laminate is satisfactory for insect anoxia.
Objects such as mummies and parchment, consisting of proteinaceous materials,
have been found to be highly susceptible to bacterial contamination. The work
discussed here shows that this contamination includes anaerobic organisms.
However, the combination of low oxygen (less than 0.1 %) and low RH (less than50%) is proved to reduce microbial activity of both aerobes and anaerobes toundetectable levels within a short exposure time.

A sealed display or storage case whose internal atmosphere (at the proper RH)
consists of an inert gas with very little oxygen constitutes an efficient system forthe preservation of many varieties of collections over the long term.
Chapter 326

Acknowledgments
The author thanks Miguel Angel Corzo and Frank Preusser for their helpful
suggestions and contributions during the initial development of this project,and Montse Algueró and Carmen Martin de Hijas for their assistance in theexperimental work on the disinfestation treatments. The author is also
grateful to the Comisión Interministerial de Ciencia y Tecnología de España(PAT 91-0047), Spain, for providing a grant for disinfestation systems in Spanish
museums and archives.

References
Bailey, S. W., and H. J. Banks
1980

Controlled Atmosphere Storage of Grains. Amsterdam: Elsevier Scientific
Publishing.
Donahaye, E.
1990

Laboratory selections of resistance by the red flour beetle, Tribolium castaneum(Herbst), to an atmosphere of low oxygen concentration. Phytoparasitica 18:
189-202.
Fleurat-Lessard, F.
1990

Effect of Modified Atmospheres on Insects and Mites Infesting Stored Products.
Boca Raton, Fla.: CRC Press.
Florian, M. L. E.
1988

Ethylene oxide fumigation: A literature review of the problems and interactions
with materials and substances in artifacts. In A Guide to Museum Pest Control,ed. L. A. Zycherman and J. R. Schrock. Washington, D.C.: Foundation of theAmerican Institute for Conservation of Historic and Artistic Works and Association of Systems Collection.
Gallo, F.
1992
Il biodeterioramento di libri e documenti. In Centro di Studi per Conservazionedelta Carta, 55-80. Rome: ICCROM.

Gilberg, M.
1991

The effects of low oxygen atmospheres on museum pests. Studies in Conservation 36:93-98.
Hanlon, G., V. Daniel, N. Ravenel, and S. Maekawa
1993

Dynamic system for nitrogen anoxia of a large museum objects: A pest eradication case study. In Proceedings of the 2nd International Conference on Biodeterioration of Cultural Property, October 5-8, 1992, held at Pacifico Yokohama,ed. K. Toishi, H. Arai, T. Kenjo, and K. Yamano, 86-90. Tokyo: International
Communications Specialists.
Hansen, E., S. Lee, and H. Sobel
1992

The effects of relative humidity on some physical properties of modern vellum:
implications for the optimum relative humidity for the display and storage ofparchment. Journal of the American Institute for Conservation 31:325-42.
Preservation of Historic Materials

27

Hutchinson, F.
1985

Chemical changes induced in DNA by ionizing radiation. Nucleic Acid Research
Molecular Biology 32:115-54.
Kenjo, T.
1980

Effects of different concentrations of oxygen on pigments used for cultural properties. Scientific Papers on Japanese Antiques and Art Crafts 25:103-7.
Koestler, R.
1992

Practical application of nitrogen and argon fumigation procedures for insect control in museum objects. In Proceedings of the 2nd International Conference on
Biodeterioration of Cultural Property, October 5-8, 1992, held at Pacifico
Yokohama, ed. K. Toishi, H. Arai, T. Kenjo, and K. Yamano, 94-96. Tokyo: International Communications Specialists.
Koestler, R., E. Parreira, E. Santoro, and P. Noble
1993

Visual effects of selected biocides on easel painting materials. Studies in Conservation 38(4):265-73.
Kowalik, R.
1980

Microbiodeterioration of library materials. Restaurator 4(2):99-114.
Maekawa, S., F. Preusser, and F. Lambert
1992

A hermetically sealed case for the display and storage of mummified objects
in a stable inert atmosphere. In Preprints of International Congress on Mummy
Studies, 79. Tenerife, Spain: Museo Arqueológico de Tenerife.
Nakamura, H., and J. Hoshino
1983

Techniques for the Preservation of Food by Employment of an Oxygen
Absorber. Tokyo: Sanyu Publishing.
Navarro, S., and E. Jay
1987

Application of modified atmospheres for controlling stored grain insects. In
Stored Products Pest Control: Proceedings of a Symposium Organised by the
British Crop Protection Council, the British Pest Control Association, and theSociety of Food Hygiene Technology held at the University of Reading, 25-27
March 1987, ed. T. J. Lawson, 229-36. BCPC Monograph 37. Thornton Heath,
U.K.: British Crop Protection Council.
Pääbo, S., J. Gifford, and A. Wilson
1988

Mitochondria DMA sequences from a 7000-year-old brain. Nucleic Acid
Research 16:9775-87.
Petushkova, P., and G. Nikolaev
1983

Nuclear magnetic resonance study of parchment and leather. Restaurator
5:242-48.

Chapter 328

Rust, M., and J. Kennedy
1993
The Feasibility of Using Modified Atmospheres to Control Insect Pests inMuseums. Marina del Rey, Calif.: Getty Conservation Institute.

Smith, C, and J. Newton
1991

Carbon dioxide: The fumigant of the future. Report presented at the International Seminar on Research in Preservation and Conservation, Columbia
University, New York.

Valentín, N.
1989

Mummy deterioration halted by nitrogen atmosphere. Nature 338:463-64.
1990
Insect eradication in museums and archives by oxygen replacement, a pilot
project. In ICOM Committee for Conservation, 9th Triennial Meeting, Dresden,
German Democratic Republic, 26-31 August 1990, Preprints, vol. 2, ed.
K. Grimstad, 821-23. Los Angeles: ICOM Committee for Conservation.
1993
Comparative analysis of insect control by nitrogen, argon and carbon dioxide inmuseum, archive and herbaria collections. International Biodeterioration and
Degradation 32(4):263-78.

Valentín, N., M. Algueró, and C. Martin de Hijas
1992

Evaluation of disinfection techniques for the conservation of polychrome
sculpture in Iberian museum. In Proceedings of International Institute forConservation Meeting on Conservation of the Iberian and Latin American
Cultural Heritage, 9-12 September 1992, Madrid, Spain, 165-67. London:
International Institute for Conservation of Historic and Artistic Works.

Valentín, N., and F. Preusser
1990

Insect control by inert gases in museums, archives and libraries. Restaurator
11:22-33.

Preservation of Historic Materials

29

Preservation of Historic Materials

30

Chapter 4This chapter describes the design requirements, the physical principles, the con-struction details, and the installation of the inert-gas-filled, hermetically sealed

Design andConstruction of
the GCI's
Hermetically
Sealed Display
and Storage Case
Shin Maekawa

display and storage case that was developed for sensitive organic and mineralmaterials at the Getty Conservation Institute. As detailed in Chapter 1, the production of the case was a project undertaken in collaboration with the Egyptian
Antiquities Organization for the conservation of the Royal Mummy Collection at
the Egyptian Museum in Cairo (Maekawa and Lambert 1993).

Introduction
Two major approaches can be considered to maintain an inert-gas microenvironment for culturally important artifacts: continuous flushing of the case with theinert gas (a dynamic system) or the use of a tightly sealed case (a static system).
The dynamic system requires a rigid case, a continuous gas supply, and active
control mechanisms and electronic devices for regulating the conditions in thecase. The inert gas that is flushed through the case must be humidified to matchthe relative humidity of the object to maintain a fixed moisture content in theobject. This demands constant control of the gas's relative humidity using a fastresponding sensor. The flushing rate should be minimized, both for the system's
safety and for economical operation. This is determined by the leak rate of thecase, which is affected by the surrounding environmental conditions (temperature and barometric pressure). The gas supply needs to be serviced and replaced
periodically. Although the concept is simple, the problem requires a complex
approach. This translates to a high cost of fabrication and maintenance. Therefore, the dynamic system is not suitable for average museums, especially indeveloping countries, where support for highly technical tasks cannot normallybe provided.
The use of these costly and sophisticated mechanical actuators and electronic
controls can be avoided if a hermetically sealed (airtight) case, the static system,
is fabricated. This case will require very little maintenance and monitoring if
its leakage is kept to an extremely small and consistent rate. The case can beproduced using existing technologies, such as fused glass, silver soldering, andO-rings. Polyisobutylene and hot-melt butyl are commonly used in the sealed
insulated glass industry for sealing glass to glass or to metal. The silver-soldering
technology was used in a storage case for the Charters of Freedom of the UnitedStates of America (MSB 1951) and the Constitution of Puerto Rico (Passaglia,
Brown, and Dickens 1983). The O-ring and gasket technologies are used in the
globe box manufacturing industry and for the construction of many hermeticallysealed pieces of equipment and have been widely used in the manufacturing ofvacuum equipment.
The construction and integrity of the case's hermetic seal depend on environmental conditions, particularly the temperature. If a gallery has little or no
climate control, the case's seal needs to be made strong enough to withstand thepressure generated by changes of temperature. Even a minor temperature variation can translate into a major force if the surface area of the case is large. The
effort of construction can be significantly reduced if the case can be built without the necessity of considering its internal pressure. This can be achieved either
by providing sophisticated temperature and barometric pressure control in thegallery or by attaching a simple pressure-compensation device or bellows to thecase. Obviously, the latter is a more attractive approach, considering the wide
applicability of the case design to museums, which are often located in historicbuildings where the installation of modern climate controls is not possible. Toishi
and Koyano have reported successful use of "an air bag attached to an airtightcase" in their design of exhibition cases for preserving humidity buffer materials(Toishi and Koyano 1988).
31

Design Concepts for the Case
The basic concept of the inert-gas-filled, hermetically sealed display and storage
system designed by the GCI is that it should provide and maintain an anoxic
environment (one with greatly reduced oxygen) at a stable relative humidity forstored or displayed objects. As outlined in chapters 2 and 3, specific requirements were established for the case: it should not rely on mechanical or electricalsystems, it should require minimum maintenance, it should be easily manufactured in a country with competent machinists, and it should be no more costly
than an ordinary high-quality museum case.

The Hermetically Sealed Display and Storage Case
General description

A static system for maintaining an inert-gas atmosphere within the case wasselected rather than a dynamic system, with its many complex components, forthe obvious reasons of simplicity and economy. The static unit also had a longterm advantage: it required little maintenance over a multiyear period because it
had no power supply and no need for periodic servicing by skilled electrical ormechanical technicians. The total GCI system consists of a display section, towhich a bellows is attached, concealed below the bottom plate, and a rigid basesupport assembly. The display case and its bellows are hermetically sealed fromthe surrounding atmosphere and filled with humidity-conditioned nitrogen,which can be monitored for oxygen content and relative humidity without opening the case (Fig. 4.1). Because of the extremely low leak rate of oxygen into thecase, when it is initially filled with nitrogen and contains no more than 0.1%
oxygen, less than 2% oxygen will be present as a result of leakage after ten
years. If a modest number of packets of an oxygen scavenger are inserted into
the case, many additional years will elapse before the 2% oxygen level isreached. A relative humidity buffering material, silica gel, that has been conditioned at a selected relative humidity should be placed in the case to provide aconstant relative humidity, compensating for temperature variations and any
moisture from the oxygen scavenger or the displayed objects. The case canFigure 4.1
Photograph of prototype hermetically sealed
display and storage case built for an Egyptianroyal mummy. Photo by T. Moon.

Chapter 432

be equipped with a septum port for removing a gas sample for gas chromatographic analysis, including the analysis of potential volatiles emitted from displayed objects. Activated carbon packets can also be placed in the case to act asa sorbent for pollutants and volatiles. Pollutants could possibly be generated by
the objects in the case, or (far less probably) from construction materials, orfrom infiltration through minute leaks over the years.
Pressure equilibration of the interior of the display case with barometric changes
in the outside atmosphere is achieved by inflation and deflation of the attached
bellows. Any potential temperature-induced volume changes in the inert atmosphere of the case are similarly automatically compensated for by the bellows. It
is this permanent pressure-neutral condition of the case that allows such a light
design and construction for the GCI hermetic seals while still assuring minimal
leakage. The display section is securely mounted on the rigid base assembly,
which provides a sturdy, flat, and completely level surface to avoid any strain on
the seals. If the clearance between the display section and this base assembly is
not adequate, the bellows can be placed inside the base assembly.
Other permanent appurtenances for the sealed case, and temporary accessories
for its testing, are described in detail here.

Construction Details of the Hermetically Sealed Case
Display section

The display section (91.5 cm wide, 182.9 cm long, and 61 cm high in the prototype case) consists of four side panels and a top section of laminated glass,
1/4 in. (6.35 mm) thick, mounted in an aluminum frame that is structurally
supported by a 2024 aluminum bottom plate of the same thickness. The bottom
plate is strengthened by two pairs of aluminum U-channel supports, each 8 in.
(20.32 cm) long, attached to it using an aluminum epoxy, one near each end
and one near each side. The frame is constructed by bolting the customdesigned extruded aluminum rods (Fig. 4.2) to the machined corner elements(Figs. 4.3-5), which are also made of 2024 aluminum alloy, with a thin film ofneutrally curing silicone sealant. This design simplified the fabrication andreduced the cost as compared with that of helium-arc-welded corners. (Extrusions of the prototype case donated to the EAO were welded at the corners.)
Seals between the glass, or the aluminum bottom plate, and the frame (Fig. 4.6)
are effected by the Viton O-rings under pressure exerted by retaining strips, precisely bent and heat-treated aluminum plates (Fig. 4.7). All the aluminum components are black-anodized to prevent corrosion from moisture and pollutants inthe atmosphere and, for aesthetic reasons in a display case, to reduce reflections
from the surfaces.
Six ports of 1/4 in. (6.35 mm) diameter are drilled, and one large access port,
8 in. (20.32 cm) in diameter, is machined in the aluminum bottom plate(Fig. 4.8). The small ports are all fitted with tube connectors and designed fornitrogen purging, recalculating to an external oxygen analyzer, attachment to a
microfilter and manometer, and connection to the bellows. The large port has an
O-ring-sealed cover with bolts welded within the circle of the O-ring (the covercloses from the inside of the case) and is used for insertion and replacement of
the oxygen scavenger, the pollution sorbent, the silica gel humidity buffer, andthe sensors. Other ports could be easily added, for example one with a septum
to allow samples of the case atmosphere to be taken with a syringe. (The air
samples can be analyzed for volatiles if it is suspected that these may be emitted
by the displayed objects. Of course, should this analytical work be of interest,
activated-carbon sorbent should not be put in the case.)
Design and Construction

33

Figure 4.2

Mechanical drawing of the extrusion profile.

An oxygen sensor and a temperature and relative humidity (RH) sensor/
transmitter are placed inside the case and their electrical leads are soldered to ahermetically sealed electrical connector mounted on the aluminum bottom plate.
Excitation voltage is supplied to the temperature and RH sensor by its monitor
outside the case; similarly, the voltage developed by the oxygen sensor isrecorded as the oxygen percentage on its external monitor. The electronic
temperature and RH sensor can be replaced by a bimetallic temperature indicator and a synthetic hair-type RH indicator. This both reduces the cost of theaccessories and simplifies their installation and operation.
The case can be equipped with a removable U-tube manometer for monitoringpressure in the case while it is purged with nitrogen. (Even small overpressures
can threaten the seals in a large case.) A pressure-relief valve can be mounted
on the aluminum bottom plate to provide additional safety against overpressure
inside the case during purging.
Bellows

A pillow-shaped bellows made of plastic and metal (Fig. 4.9) is connected using
an O-ring-sealed male tube connector on one of the corners of the "pillow" tocopper tubing that leads to fittings in the aluminum bottom plate. The bellows ismade by heat-sealing two rectangles of oxygen barrier film, such as Marvelseal
360 (a laminated film of nylon on aluminized polyethylene) or Filmpak 1193
(ethylene vinyl alcohol-laminated film), at all four edges after holes are carefully
cut in the bellows and the tube connector is inserted and tightened. The bellows
functions by expanding and contracting during external temperature or barometric fluctuations, thereby preventing any pressure on the seals of the display
section. The bellows, whose volume is recommended to be at least one-tenth ofthe display section's volume for a 25 °C temperature variation in the external
Chapter 434

Figure 4.3

Mechanical drawing of a corner
element.

#10 bolt-headclearance(typ. 3 places)#10 bolt-hole
clearanc e(typ. 3 places)

1/16 in. (1.59 mm) pin
press fit (typ. 6 places)
0.12 in. (3.05 mm) deep

environment, rests directly below the aluminum bottom plate with enough vertical clearance for its expansion. (It must be supported from below to avoid
placing any strain on the O-ring seals in its tubing fittings.) A larger bellows is
recommended if greater temperature variations are expected where the case is
to be located. To avoid leaks arising from stresses on the film or on its seam andO-ring seals, the bellows should be not be twisted or constrained in any way.

Passive control agents
Oxygen Scavenger The commonly used oxygen scavenger Ageless (Fig. 4.10),
developed for the packaged-food industries, has been successful in preventing
the oxidation of food as well as the growth of microorganisms. It consists of afinely divided iron oxide powder, potassium or sodium chloride, and a zeolite
containing water, packaged in an oxygen-permeable plastic packet. Reaction
with oxygen of the type of Ageless called Ageless-Z is most rapid at 75% RH,
but it is significant even at 45% RH. Ageless-Z contains approximately 3.4 g ofwater in the Z-1000 packets, which are said to absorb 1000 cc of oxygen. (Thepackets bear designations from Z-100 to Z-2000 to indicate their oxygenabsorbing capacities. The manufacturer has been putting enough chemical ineach packet to react with three times its nominal oxygen capacity, to allow for
exposure to ambient air during the placement of the packets in packages.) The
Design and Construction

35

Figure 4.4

Mechanical drawing of a drilled extrusion end
for the corner assembly.

Figure 4.5
Photograph of the corner assembly.

Chapter 436

Figure 4.6
Schematic of the hermetic seal.

number of packets that must be placed in the case can be determined from theoxygen leak rate of the case and the desired length of time before the packets
need to be replaced. The kinetics of the reaction of Ageless with oxygen insealed cases are reported by various investigators (Abe and Kondoh 1989;
Mitsubishi Gas Chemical Co. 1994; Lambert, Daniel, and Preusser 1993).

Relative Humidity Buffer The case does not need protection from infiltration ofmoisture from, or loss to, its surroundings because its leak rate is so low. However, moisture can enter or leave the case whenever it is opened, for instance,
during replacement of the passive control agents or servicing of the sensors. An
oxygen scavenger, such as Ageless, itself contains a small amount of water andthe moisture is released over time. The object displayed in the case may not beat its optimal long-term RH level and even multiday purging with nitrogen at this
RH does not bring it to that level. Temperature changes in the case result in RH
fluctuations. To moderate these rapid fluctuations somewhat and to insure thelong-term maintenance of the proper RH, an appropriate amount of humidity

buffer should be inserted just before the case is sealed.
Selection of a humidity buffer, such as silica gel, Artsorb, or molecular sieves,must be based on the effectiveness of the material in the RH range at which theobjects will be stored, the cost, and the local availability of the products. The
amount to be used depends on the volume of the case and the hygroscopic
Design and Construction

37

Figure 4.7
Mechanical drawing of the retention strip.

Material: 0.04 in. (1.02 mm) aluminum
5000 Series heat-treatedView A-A(no scale)

Retention strip(all measurements in inches)

Figure 4.8
Mechanical drawing of the bottom plate.

Baseplate assembly detail(all measurements in inches)

Chapter 438

Figure 4.9

Photograph of the aluminum-plastic bellows.

capacity of the object as described by investigators (Thomson 1986; Weintraub1980). Spreading the buffer in trays that afford the largest convenient surface
area will facilitate a rapid response to change, resulting in a stable RH level.
Pollution Sorbent The case is designed for use with packets of pollution sorbent
to protect the contents from internal pollutants and from ingress of any undesirable substances from the external environment. Internal pollutants include volatile gases slowly emitted from the displayed objects and minute outgassing ofsome component of the case, such as the O-rings. Even though the compositionand quantity of these internal pollutants have not been thoroughly investigated,
those of outdoor and museum pollutants and their levels have been well studied.
Therefore, the selection of the pollution sorbent has been based on the studies
by Parmar and Grosjean of undesirable substances in a typical museum (Parmarand Grosjean 1990). Activated carbon is capable of absorbing these museum
pollutants of Nox, SO2, CO, CO2, O 3, and hydrocarbons at a level of approximately 50 ppb. The quantity to be used is calculated from the case size and thetime before service will be required.

Figure 4.10
Photograph of an oxygen scavenger, Ageless.

Design and Construction

39

Evaluation of Performance and Installation
Leak testing and performance evaluation

Descriptions of the procedures that were used for the GCI sealed case and theresults that were observed are given in the following section. First, the case andbellows were tested for major leaks using Freon or helium gas in the case andchecking to find any transmission through seals by using a halogen detector.
Then the case and bellows were thoroughly purged with dry nitrogen. The
resulting nitrogen-filled system was allowed to equilibrate, and the initial oxygen
concentration was measured by circulating a gas stream from the case througha metal diaphragm pump and trace oxygen analyzer and back to the case andbellows.
During the testing period, the temperatures of the room and of the sealed casewere periodically raised as much as 10 °C above normal room temperature tosimulate variations of temperature and barometric pressure that might occur
under actual extremes of gallery conditions. Oxygen concentrations in the casewere measured daily for seven to ten days to determine the average oxygen(and thereby air) leak rate of the case.

The leak rate of atmospheric oxygen into the case ranged up to approximately
20 ppm per day for the arc-welded prototype, which had a volume of 1000 I. It
improved to less than 5 ppm per day for five new cases (four of 500 I and one of96 I) produced with a later improvement in design: the use of bolted corner elements. At an achievable leak rate of 5 ppm per day, if the oxygen concentrationin the sealed case is brought down to less than 0.1 % (1000 ppm), it will takemore than ten years for the oxygen concentration inside the case to reach 2%.
(This is without the presence of an oxygen scavenger, of course, and it assumes
a constant leak rate over the ten-year period.)
In ten years, a calculated 18000 cc of oxygen will leak into the case, the amountthat can be absorbed by nine packets of Ageless Z-2000 or eighteen of Ageless
Z-1000. Therefore, the maintenance-free period of the case could be extended
to twenty years by the insertion of Ageless. It can be further extended to forty
years by inserting eighteen packets of Z-2000 or thirty-six packets of Z-1000.
Purging of the Case in the Presence of Objects It is essential to control the
relative humidity in a display case when an object has been placed inside it.
Therefore, nitrogen gas that is passed into the case containing an object must be
carefully humidified. Figure 4.11 is a simplified schematic of the original nitrogengas supply system. RH-conditioned nitrogen is produced by controlling the mixing ratio of dry nitrogen from the tank to moist nitrogen (produced by bubblingtank nitrogen through water at room temperature). Maekawa and Elert haverecently published the details of a gas humidification system whose controllability has been significantly improved (1996).

As the RH inside the case is being adjusted by humidified nitrogen and the oxygen is being purged, a trace oxygen analyzer is used to follow the decrease inoxygen each day. The purging process is near its end when the oxygen content
reaches 1000 ppm.
The exhaust port of the case can be fitted with a microfilter to prevent bacteria
and fungal spores on the object from being dispersed to the museum atmosphere during flushing. Pleated Teflon (PTFE) membrane filters with a retention
rating of 0.5 mm and a large filtration area should be selected to prevent
disastrous pressurizing of the case and bellows.
Chapter 440

Figure 4.11

Schematic of the purging setup.
RH and oxygen
monitors

Valve

RH monitor

Display casewith objects

Microfilter
WaterbottleBellows

Nitrogen
supplyWhen the oxygen level in the case is below 1000 ppm, the appropriate amountsof passive control agents, humidity buffer, oxygen scavenger, and pollution
sorbent are placed in the case through the access port. (To minimize the introduction of air during this step, the nitrogen flow can be increased greatly when
the large port is open. However, extreme vigilance must be exercised to instantly
decrease the nitrogen flow to the previous slow rate as soon as the port isnearly closed, after the placement of the agents.)
Once these procedures have been completed and the access door is tightly
bolted, the valves from the nitrogen supply system and to the microfilter areclosed and both the microfilter and the tubing to the nitrogen are removed
from the case. Similarly, valves to the trace oxygen analyzer are closed and its
tubing to the case disconnected.
Reflushing of the case with nitrogen is necessary when the oxygen concentration in it, as measured by its internal passive monitor, reaches 2%. The control
agents can also be renewed at this time.

Summary
A hermetically sealed display and storage case that can be filled with an inert gas
was successfully designed, fabricated, and tested at the Getty Conservation
Institute. Maintenance of the case requires no electrical or mechanical system.
Because it is relatively easy to build without special tools and requires only askilled machinist for its fabrication, it can be made both in developed and developing countries. Humidity-conditioned nitrogen was used as the inert atmosphere in the first GCI display case; other inert gases, such as argon and helium,
can be substituted. Because the case can be built so that only 5 ppm per day orless of atmospheric oxygen will leak into it, the maintenance-free life of thecase is approximately ten years if the case is purged to an initial oxygen level of1000 ppm. This period can be extended to more than twenty years if a modest
quantity of oxygen scavenger is introduced after the initial purge.
The display cases have now been produced by the Supreme Council of Antiquities for the display and storage of the Royal Mummy Collection at the EgyptianMuseum in Cairo; for an Egyptian child mummy at the Biblioteca-Museu Victor
Balaguer in Vilanova i la Geltrú, Spain; and for the Constitution of India at theParliament Library in New Delhi, India. Most recently, Dorset Conservation, Inc.,of Toronto successfully built a GCI-designed hermetically sealed display and
Design and Construction

41

storage case for the Royal Proclamation Charter for the Company of Adventure,
Hudson's Bay Company, Toronto.

Because construction of the case is labor-intensive (approximately 100 hours ofa master machinist's work), its cost varies depending on the country where it isproduced. In the United States, the cost of building a 1000-liter case in 1992
was approximately US$10,000, but this cost could be significantly reduced if
several cases are fabricated at the same time.

Acknowledgments
The project was initially directed by Frank Preusser and later by Neville Agnew.
Frank Lambert developed leak-testing procedures. Detailed mechanical design
and fabrication of the prototype case were contracted to Lightsense Corporation, Laguna Beach, California. Mitsubishi Gas Chemical Company donated theAgeless oxygen absorber throughout the project. The author thanks these firms
for their cooperation and technical support throughout the project.

Materials and Suppliers
Extrusion
Profile parts number: TMS 60-30780; alloy: AL 6061; temperature treatment:
T6511
Source: Tiernay Metals, 2600 Marine Ave.f Redondo Beach, CA 90278-1197
O-ring cord stock
Material: Viton; nominal diameter 1/8 in. (3.18 mm)
Source: McMaster-Carr Supply Co., 9630 Norwalk Blvd., Santa Fe Springs, CA
90670 (or local O-ring supplier)
GreaseSilicon O-ring lubricantsHigh-vacuum grease
Source: McMaster-Carr Supply Co. (or local hardware suppliers)
Glass Panels
1/4 in.- (6.35 mm) thick laminated glass
Bottom Plate
Aluminum epoxy (Devcon aluminum-filled epoxy)
Source: McMaster-Carr Supply Co. (or local hardware supplier)Tube connector: 1/4 in. (6.35 mm) Swagelok O-seal straight thread maleconnector
Valve: Whitey model 42S4 1/4 in. (6.35 mm) 2-way valve
Hermetically sealed electrical connector (electrical feedthrough)Sources:
Douglas Engineering Company, 14 Beach St., Rockaway, NJ 07866
Omega Engineering, 1 Omega Dr., Stamford, CT 06907
Aluminum sheet: 1/4 in. (6.35 mm) sheet (alloy: 2024 Series aluminum)U-channels: 8 in.- (20.32 cm) base U-channels (alloy: 5000 Series
aluminum)

Access Plate
O-ring: APR 568-365 (material: Viton)
Source: O-Rings, Inc., 2260 Centinela Ave., Los Angeles, CA 90064 (or local
O-ring suppliers)
Aluminum plate: 1/2 in. (1.27 cm) aluminium plate (alloy: 5000 Series)
Chapter 442Threaded Studs: no. 10-32 (4.8 mm diameter, 95 mm deep) Wing Nuts: no.
10-32 (4.8 mm diameter, 12.7 mm deep)
Washers: no. 10 (4.8 mm inner diameter)
Corner Element
1 in.- (2.54 cm) square stock rod (alloy: 2024 Series aluminum)
Button-head cap screw: no. 10-32
Stainless steel pins: 1.6 mm diameter, 8 mm long
Noncorrosive RTV silicone filler: Dow 748 Noncorrosive RTV Silicone or GE
Noncorrosive Fast-Cure RTV Silicone
Retention Strip
1/16 in.- (1.59 mm) thick aluminium sheet (alloy: 6061 Series aluminium,
heat-treated)
Button-head cap screws: no. 6-32, 0.953 mm
Oxygen Sensor
Model 320 Portable Oxygen Analyzer or Model 311 Portable Trace Oxygen
Analyzer
Source: Teledyn Analytical Instruments, 16830 Chestnut St., City of Industry,
CA91749
Bellows
Marvelseal 360
Filmpak1193
Source: Ludlow Laminating and Coating Division, Homer, LA 71040
Heat-sealing iron
Tube connector: 1/4 in. (6.35 mm) Swagelok O-seal straight thread male tube
connector
Nuts: no. 7/16-20
Washers: Dash no. 815, 3/8 in. (9.53 mm), 0.438 in. (1.1125 cm) innerdiameter, 1 in. (2.54 cm) outer diameter
Source: McMaster-Carr Supply Co. (or local hardware shops)
Temperature/Relative Humidity Sensor and Thermo-Hygrometer
Source: Cole-Parmer Instrument Co., 7425 North Oak Ave., Niles, IL 60714
Leak Detector
Halogen Leak Detector
Source: Gas Tech Inc., Newark, CA
Custom Humidification System
High-density polypropylene bottles
Flow meter
Nylon tubing
Sources:
Fisher Scientific, 711 Forbes Ave., Pittsburgh, PA 15219
Cole-Parmer Instrument Co., 7425 North Oak Ave., Niles, IL 60714
Tube Fittings and Connectors
Source: Swagelok Co., 31400 Aurora Road, Solon, OH 44139
Valves
Source: Whitey Co., 318 Bishop Road, Highland Heights, OH 44143
NitrogenSource: Union Carbide Industrial Gases Inc., Linde Division, Somerset, NJ 08875(or local gas suppliers)
Design and Construction

43References
Abe, Y., and Y. Kondoh
1989

Oxygen absorbers. In Controlled/Modified Atmosphere Vacuum Packaging ofFood, ed. Aaron L. Brody, 149-58. Trumbull, Conn.: Food and Nutrition Press.
Lambert, F., V. Daniel, and F. Preusser
1993

The rate of absorption of oxygen by Ageless: The utility of an oxygen scavenger
in sealed cases. Studies in Conservation 37:267-73.
Maekawa, S., and K. Elert
1996
Large-scale disinfestation of museum objects using nitrogen anoxia. In ICOM
Committee for Conservation 11th Triennial Meeting, Edinburgh, Scotland,
1-6 September 1996, Preprints, ed. J. Bridgland, vol. 1, 48-53. London: Jamesand James.
Maekawa, S., and F. Lambert
1993

The Getty Conservation Institute's Inert Atmosphere Display and Storage Casefor the Pharaonic Mummies of the Egyptian Museum, Cairo, Final Report. GCIScientific Program Report, December.
Mitsubishi Gas Chemical Co.
1994

Ageless Oxygen Absorber: A New Age in Food Preservation. Tokyo: Mitsubishi
Gas Chemical Co.
National Bureau of Standards (NBS)
1951

Preservation of the Declaration of Independence and the Constitution of theUnited States. NBS Circular 505. Report by the National Bureau of Standards to
the Library of Congress, July 2, Washington, D.C.
Parmar, S. S., and D. Grosjean
1990

Sorbent removal of air pollutants from museum display cases. Environment
International 16(6):39-50.
Passaglia, E., D. Brown, and B. Dickens
1983
The preservation of the Constitution of Puerto Rico. Final Report NBSIR83-2473,
National Bureau of Standards, Washington, D.C.

Thomson, G.
1986

Museum Environment. 2d ed. London and Boston: Butterworths.
Toishi, K., and M. Koyano
1988

Conservation and exhibition of cultural property in the natural environment in
the Far East. In The Conservation of Far Eastern Art: Preprints of the Contributions to the Kyoto Congress, 19-23 September 1988, ed. John S. Mills, Perry
Smith, and Kazuo Yamasaki, 90-94. London: International Institute for Conservation of Historic and Artistic Works.
Chapter 4

44

Weintraub, S.
1980
A New Design for a Low Maintenance Silica-gel System for the Control of Relative Humidity in a Sealed Case. In Conservation within Historic Buildings: Preprints of the Contributions to the Vienna Congress, 7-13 September 1980, ed.
N. S. Brommelle, Carry Thomson, and Perry Smith, 55-56. London: International
Institute for Conservation of Historic and Artistic Works.

Design and Construction

45

Design and Construction

46

Chapter 5

ControlledEnvironment Cases
for the Royal
Mummy Collection
Nasry Yousef IskanderThis article describes the work of constructing hermetically sealed cases to preserve and display the collection of royal mummies at the Egyptian Museum in
Cairo. Based on the prototype of a hermetically sealed display and storage casedeveloped and presented to the Egyptian Museum by the Getty Conservation
Institute, the cases were made, insofar as possible, from materials that werelocally available in Egypt.
Even with the continual support of the GCI, the project proved to be difficult. A
number of cases were completed, however, that are quite similar to the original
GCI prototype, and they are functioning well. They should succeed in protecting
these historically important mummies. The 1994 cost per case in Egypt wasapproximately US$2,000, suggesting that display cases of this sort can be madefor treasured objects in other countries for quite reasonable amounts.
Excavated mummies are threatened by microbiological growths, insect attacks,
air pollution, and large fluctuations in temperature and humidity. The EgyptianMuseum in Cairo has a collection of twenty-seven royal mummies (Fig. 5.1)
whose preservation is of both national and historical concern. As discussed inchapter 1, the Egyptian Antiquities Organization (EAO; now the Supreme
Council of Antiquities) collaborated with the Getty Conservation Institute todesign and produce the prototype of a display (or storage) case that would
protect mummies from all of the aforementioned threats, except temperaturefluctuations.
The complex research and development required for this unique case was completed by GCI staff and contractors working under their direction in late 1988;
construction of the prototype model and testing were finished by early 1989. In
May of that year, the prototype was presented to the EAO, whose task it then
was to fabricate some twenty-seven cases based on the GCI's design using
Egyptian materials and workers.

Case Construction in Egypt
The major task of the EAO during the first year was trying to duplicate someof the ingenious features of the GCI prototype. Essential components of thehermetic seal of the case are the twelve slender extrusions that make up its
frame and contain grooves for the O-ring seals that fit into them. The mostFigure 5.1
Photograph of the old Royal Mummy Room in
the Egyptian Museum, Cairo, Egypt. Photo by
Guillermo Aldana.

47

complex of the components are the eight welded corners that hold the twelve
extrusions.
These corners posed a special problem because in the original GCI design they
are precisely arc-welded. Using the EAO's facilities and available techniques or
those that could be located in Egypt, fabricators found that the heat of welding
was causing serious distortions at the corners. They found it impossible to produce the welded corners that could ensure accurate extrusion attachment andO-ring placement to guarantee a perfect hermetic seal at these critical points.
Initially, procurement of the aluminum extrusions for the frames of the cases also
proved difficult, even though there are competent aluminum fabricators in
Egypt. Thanks to the GCI, a design improvement for the corners that uses screws
instead of welding was sent to the EAO in late 1989. The drawing for the new
design was further clarified by Shin Maekawa of the GCI, who made several trips
to Egypt to provide invaluable aid, both in interpreting the plan and in helping tosolve a number of other problems in this first phase of the project.
Because of the limitations of local suppliers, it was necessary to modify several
components of the GCI design. Figures 5.2 and 5.3 show schematic drawings ofthe EAO version of the GCI-designed case. For example, a decision was madeto use 7 mm tempered glass for the sides and top rather than the 1/4 inch
(6.35 mm) laminated glass of the original, and to use 3 mm nonanodized aluminum sheet with a 3.5 mm plywood backing for the baseplate rather than a blackanodized 1/4 inch (6.35 mm) aluminum baseplate. Machining brass is mucheasier than machining aluminum; thus, the corner elements were made frombrass. Heat-treating the aluminum retention strips to make them springlike inholding the glass sides and top to the frames was not easy, so strips that were

Figure 5.2

Aluminum
extrudedframe

Exploded view of the Egyptian Antiquities
Organization's version of the hermeticallysealed display and storage case designed by
the Getty Conservation Institute.

RH and °C, scale
Service hole
Septum port
O 2 sensor contacts

Aluminum
baseplateNitrogen in
Nitrogen out
Bellows
Wood frame
under aluminum base

Wood standframe with bellows

The wood stand

Chapter 5

48

Service hole
Septum port
O2 sensor contacts
Nitrogen in

To bellows
Nitrogen out

Figure 5.3
Schematic drawings of the EAO's hermeticallysealed display and storage case.

somewhat thicker (without heat-treating) were used to achieve a similar goal.
Because of their thickness, the number of screws holding the sides and top could
be reduced by placing screw holes at 10 cm rather than 5 cm intervals. Two final
modifications were the doubling of the size of the bellows from about 100 I to
about 200 I, and the use of a round steel access cover in the baseplate instead of
a 12.7 mm aluminum cover.
For a shape that would be more suitable for display of the mummies in the
Egyptian Museum, we changed the size of the case (to 80 cm wide by 60 cm
high by 200 cm long, rather than 91 cm by 60 cm by 183 cm). Further, theoverall height of the support beneath it was reduced, and the light colored wood
frame that was made hides the metal edges for greater visual appeal.
Finally, in 1991, the first case was assembled, with its valves in the baseplate (forinput of nitrogen, output to the oxygen analyzer, and connection to the bellows)
and its glass sides, glass top, and baseplate firmly fitted by the retention strips
to the O-rings, which were thinly coated with silicone grease. The EAO teamthen began the leak-testing process. With the access cover in the baseplate
partly open, the air was thoroughly flushed from the case using a rapid flow ofnitrogen through the input valve. Quickly closing the door after stopping thenitrogen flow, the team started the pump to circulate the case's atmospherethrough the oxygen analyzer and back to the case.
Unfortunately, the initial leak rate was 500 ppm of oxygen per day, approximately 25 times what the GCI had measured in the prototype. By applying
neutrally curing silicone elastomer to the corners (the most probable source ofleaks), the oxygen leak rate was reduced to 200 ppm per day. However, this was
still ten times what is desirable for long-term sealing of the case atmospherefrom the outside museum air. It took seven months of work—repeatedly
disassembling and reassembling the entire structure, carefully sealing the corners
and any missed spots on the O-rings with silicone grease, replacing the bellows
several times, and retesting—to achieve a leak rate of 50 ppm per day.
Continuing work over the next two years involved not only such problems as
successfully machining a die through which to extrude the frames of the case,but also identifying a company capable of producing the extrusion at a reasonable cost and agreeing to carry it out. Finally, an aluminum window manufacturer in Ismailia, Egypt, agreed to produce the hot extrusion for approximately
US$20 per meter in large quantities. A sample of the product was sent to the
GCI and it was found to be adequate, although it was not of the originally specified 6066 aluminum alloy. Then, with frames, corners, and other less complex
components of the case at hand, it was possible to proceed with the assembly ofseveral cases and to proceed to test their hermetic integrity.

For those planning to construct similar sealed cases, here are a few details of
testing that may be of value, based on the experience reported here: It is usefulControlled-Environment Cases

49

Figure 5.4
The author with the EAO's newly assembled
hermetically sealed display cases in the
Egyptian Museum. Photo by Shin Maekawa.

to install a small fan in the case and turn it on to eliminate any stratification justprior to circulation of the case atmosphere through the external oxygen analyzer. To avoid breakage of the glass panels of the case or, almost equally disastrous, deflection of the glass on the O-rings, one must be careful not to raise theinternal pressure to more than 68 mm of water. (This slight pressurization isessential when employing the trace-gas-halogen leak detector, a useful test
method recommended by Maekawa.) The other leak-test instrument, the oxygen analyzer, should not be exposed to air for long periods of time; it is best to
keep oxygen-free nitrogen in the sensor compartment.
Simply looking at the state of inflation of the bellows provides a crude indicationof leaks into the case. Because the bellows is left partially filled with nitrogen
after air has been flushed from the case with nitrogen, if it is observed to be flat
any time afterward, this indicates that there is a major leak in the bellows or in
the case.

Figure 5.5
Photograph of the newly opened Royal
Mummy Room (Room 56) in the EgyptianMuseum. Photo by Shin Maekawa.

Finally, by November 1994, fifteen cases had been completed and, when tested,
had a leak rate of less than 20 ppm of oxygen per day (Fig. 5.4). Each case wasfitted with a hygrothermometer (donated by the GCI), visible from the exterior,in addition to the access cover and valves and bellows previously described.
Activated carbon was placed in each case containing a mummy, although themodification did not allow space for silica gel packets for RH maintenance or for
similar units of a scavenger to remove residual oxygen. The current plan is tocomplete a total of twenty-seven display cases for the refurbished Royal
Mummy Rooms, which ultimately will contain all of the royal mummies.

The Royal Mummy Rooms
Located in the east end of the Egyptian Museum, near the entrance to the Tutankhamen exhibit, the first of the completed Royal Mummy Rooms is on thesecond floor. A large area near the gates to this room is reserved for many
displays related to mummification—from tomb objects to mummification tools
to drawings from the Book of the Dead. Physically, the Royal Mummy Room(Fig. 5.5) has been made more attractive (while permitting concealment of airChapter 550

Figure 5.6

Photograph of members of the EAO team who
built, tested, and installed the hermeticallysealed display and storage cases for the Royal
Mummy Collection at the Egyptian Museum.
Photo by Shin Maekawa.

conditioning ductwork) by lowering its ceiling to 3 m, in contrast to the manyrather austere 8 m high galleries in the museum. The floor size is 8 m x 13 mand, thus, with the low ceiling, marble floor and walls, and massive rectangularcolumns, the overall effect is one of an enclosed space remotely like a tomb,albeit an elegant one. That feeling is somewhat enhanced by the nearly concealed ceiling illumination provided by UV-filtered halogen spot lamps, individually controlled to limit the light on the mummies to less than 50 lux. The vitally
important air-conditioning is maintained by three independent systems, two of
which alternate each eight hours and one of which acts as a standby unit. The
room's temperature is maintained at 21 °C day and night, and its relative humidity is controlled by a mobile dehumidifier, manually activated when the visitor
load is high. Even when the air-conditioning malfunctioned occasionally during
the initial use of the Royal Mummy Room, the RH and the temperature within
the cases remained in the optimal ranges of 35-40% and 21-24 °C respectively.
The first Royal Mummy Room currently holds eleven mummies,1 ten of themhoused in hermetically sealed cases and one, Ramses II, in a French-built case.
Long before they were transferred to sealed cases, the mummies had been in
ordinary display cases where the average ambient relative humidity was in the
55% range. To prevent cracking of the skin or similar harm, the RH in thestorage cases was slowly reduced, over a period of three months, to between
35% and 40%, the optimal level for long-term storage. The Supreme Councilof Antiquities is planning to display an additional sixteen mummies in the2second room.

Conclusion
Because of the remarkable original case design and the invaluable aid affordedby the GCI, together with a large investment of labor by others in Egypt, it has
been shown that hermetically sealed cases can be constructed in countries thatlack highly developed industrial facilities. The staff of the Egyptian Museum in
Cairo look forward to the successful preservation of its entire Royal Mummy
Collection and its presentation in the Royal Mummy Rooms to travelers fromaround the world.
Controlled-Environment Cases

51

Acknowledgments
Individuals involved in the work included EAO advisers Shawky Nakhla andMohammed Saleh; EAO members Ibrahem Ramzy, Asma El-deeb, Samia Emara,
Soher El-Saoui, Gamal El-Bony, Sobhy Samoel, Hanan Nyroze, Mervat Resk, andSeham Shafek; and team members Aber Helmy, Khaled Ahmed, Mohammed
Atia, Tarik Mohammed, Ashraf Abd-Elsamea, and Samy Abd-Elgany (Fig. 5.6).

Notes
1. Mummies on display in Royal Mummy Room I, Room 56: Amenhotep I,
Henuttawi, Merneptah, Queen Merytamun, Nedjemet, Ramesses II,
Ramesses V, Seti I, Seqenenre Ta'a, Tuthmosis II, Tuthmosis IV.
2. Mummies to be displayed in Royal Mummy Room II, Room 52: AhmesNefertari, Ahmose I, Amenhotep II, Amenhotep III, Esemkhebe, Ramses III,
Ramesses IV, Ramesses IX or XII, Ramesses VI, Seti II, Siptah, Sitkamos,
Tuthmosis I, Tuthmosis III, Queen Tiye, Yuya. The latter two mummies arefrom the nobility, rather than of royal birth.

Chapter 552

Chapter 6

Preservation of
the Original
Documents of theConstitution of
India
Hari Kishan and Shin Maekawa

The original documents of the Constitution of India (Fig. 6.1) comprise twobound calligraphed volumes in English and Hindi. Since their creation nearlyfour decades ago, both volumes have been housed in the Parliament Library in
New Dehli.
The work of framing free India's Constitution commenced with the first meetingof the Constituent Assembly, held on 9 December 1946. After deliberating fornearly three years, the Constituent Assembly adopted the Constitution on
26 November 1949, and it took effect on 26 January 1950. The Constitution as
originally adopted had twenty-two parts, comprising 395 articles and eightschedules. Its present text is amended from time to time. During the last
forty-four years, there has been a total of seventy-five amendments.
At the insistence of then-Speaker Shri G. V. Mavalankar and then-Prime Minister
Pandit Jawaharlal Nehru, the English version of the Constitution was preparedby an expert calligrapher, Shri Prem Bihari Narain Raizada of Delhi, who completed the task in about eighteen months. The document consists of 233 sheetsof handmade parchment paper procured in England, measuring 45.7 cm by
58.4 cm, and weighing 13 kg. The handwritten pages were illuminated by theprominent artist Shri Nand Lal Bose of Shanti Niketan. Every page is beautifully
embellished. At the beginning of each section of the Constitution, the illustrations by Shri Nand Lal Bose depict scenes from the Mohanjodaro and Vedic
periods up through the time of India's Freedom Movement. The illumination
process took about four years. For the Hindi version of the document,
264 sheets of handmade parchment paper, measuring 45.7 cm by 58.4 cm andweighing 14 kg, were made by the Hand Made Paper Research Centre, Pune,
India. This document was penned by Shri Basantrao Vaidya, who also executed
the decorations. The binding process took almost one year.
These documents have great autographic as well as historical value, because
they contain the signatures of the founding fathers of the Constitution, many ofwhom subsequently played pivotal roles in shaping the destiny of the country.
The Conservation Project
The important task of devising a solution for the long-term preservation ofthese historic volumes began in the mid-1980s and gained momentum after thattime. To determine the state of preservation of the documents, the Parliament
Library contacted the National Research Laboratory for Conservation of Cultural

Figure 6.1
The two bound volumes that contain theoriginal documents of the Constitution ofIndia. Courtesy of the Parliament House,
Government of India.

53

Property at Lucknow, India. Their report—which included the results of optical
testing, the brightness of the paper, and the gloss of the gold on the document—concluded that both volumes were in fairly sound condition (National
Research Laboratory 1994).
At the request of the Parliament Library, the National Physical Laboratory (NPL)in New Delhi began to develop a case for preserving the documents. The NPL
developed the concepts of displaying and storing the documents in sealed glass
cases with inert-gas atmospheres.
The most challenging aspect of constructing such a display case is producing anadequate seal. It must be hermetically tight and mechanically sound so as towithstand changes in temperature and atmospheric pressure. Other requirements of the seal are that it remain durable over many years and that it notallow contamination of the documents stored in the case. After an extensive
literature search on the subject, three available methods for producing hermetic
seals were identified and evaluated: silver-lead soldering, organic sealants, andmechanical seals using O-rings. From 1988 to 1989, the NPL fabricated cases
using tempered-glass sheets and a silicone-rubber sealant. Apart from being
esthetically inadequate, the cases were not satisfactory for two reasons: first, thedurability of the seal over many years could not be assured; second, the organic
polymeric materials from which the seals were made were found to emit volatilegases, which could have had an adverse effect on the contents of the case.
Simultaneously, extensive research efforts directed toward the development of ahelium leak detector capable of measuring small quantities of air ingress into ahelium-filled case were also made at the NPL. The instrument consisted of four
fine platinum-tungsten coils and a Wheatstone network. Measurements over a
period of about two years indicated that the system was reliable, rugged, andreproducible and could detect as small a change as 0.5% air ingress into ahelium-filled case.
Several prototype glass cases were fabricated, and hermetic sealing was attemptedusing a soldering technique similar to the one developed by the U.S. National
Bureau of Standards (now the National Institute of Standards and Technology)
for the preservation of the Declaration of Independence and the Constitution of
the United States (National Bureau of Standards 1951). Again, however, acceptable seals were extremely difficult to produce. At this stage, various national andinternational institutes and laboratories were contacted for assistance.
Through the courtesy of the French Embassy in New Delhi, Hari Kishan of the
National Physical Laboratory visited France from September 1992 to February
1993 to obtain technical aid in the development of hermetically sealed glass
cases. During this period, two cases—one sealed by the soldering process(Fig. 6.2) and the other with O-rings (Fig. 6.3)—were constructed with support
provided by the Saint-Gobain Company, Paris. It was concluded from this investigation that for the long-term preservation of the Constitution, the O-ringsealing technique was far superior to the soldering method because of the difficulty of consistently producing a secure soldered seal.
During this period, it was suggested that Kishan contact the Getty Conservation Institute to obtain technical assistance in the O-ring sealing technique. In
November 1992, a request for assistance was made to the GCI.

Collaboration Between the NPL and the GCI
In response to the NPL's request, the GCI sent a report on the royal mummy conservation project, which had been carried out in collaboration with the Egyptian
Chapter 654

Figure 6.2
Hermetically sealed glass case, sealed
by soldering. Photo by Shin Maekawa.

Antiquities Organization (Maekawa and Lambert 1993). The report contained
the concept and design details of the GCI's hermetically sealed display and storage case. Shortly after the report was sent, the GCI offered to construct thecases for the Constitution of India, provided that the cases would be used tohouse these culturally and historically important documents. A letter of intent
between the NPL and the GCI was signed in July 1993. It detailed plans to collaboratively design, install, and test the Institute's hermetically sealed cases,
which would be fabricated for the preservation and display of the constitution
documents.

Design and Fabrication of the Cases
The following are edited portions of the agreement between the NPL and the
GCI regarding the cases for the Constitution of India:
1. Two identical cases will be fabricated, one for the English and the other for
the Hindi version of the document.
2. The internal volume of each case will be 96,250 cm3, and the dimensions ofeach will be 55 cm wide, 70 cm long, and 25 cm high.
Figure 6.3
Hermetically sealed glass case, sealedby O-rings. Photo by Shin Maekawa.

Preservation of Original Documents

55

Figure 6.4

Mechanical drawing of the baseplate of the display case designed by the GCI.

Baseplate assembly detail(all measurements in centimeters)

3. The documents will be stored and maintained at a relative humidity of 4050% in a nitrogen atmosphere with an oxygen concentration of less than 1%

by volume.
4. A special protective vaultlike room, 180 cm wide, 180 cm deep, and 305 cm
high will be constructed in the Parliament Library at the Parliament House fordisplay and storage of the documents. The room will be climate controlled tomaintain a temperature of 20 °C ± 2 °C and a 30% ± 5% relative humidity
throughout the year.

It was also agreed that the cases would be constructed at the GCI in the UnitedStates and transported to the Parliament Library in New Delhi, where they would
be installed and jointly tested by the GCI and the NPL.
Based on the above requirements, the GCI staff prepared a set of mechanicaldrawings of the cases, and three identical cases were simultaneously fabricatedin the machine shop of the GCI (Fig. 6.5). A total of 120 work hours were spent
by GCI's master machinist on the project. Three cases were built, and after brief
oxygen-leakage testing, two of them were crated and transported to New Delhi
for installation in the Parliament Library in March 1994.

Installation of the Display and Storage Cases
Figure 6.5

Photograph of cases built at the GCI, Photo by
Shin Maekawa.

Chapter 6

Because of a delay in the construction of a Parliament Library building where theproposed vaultlike room for the Constitution was to be located, the cases were
temporarily installed in a small side room attached to a central meeting room in
the Parliament Library at the Parliament building for in situ performance testing56

Figure 6.6
Cases displaying the Constitution of India,

temporarily installed in a small side room of
the Parliament Library, New Delhi. Photo by

Shin Maekawa.

(Fig. 6.6). The room is on the second floor of the massive, toroidal three-story
building, which is made of large blocks of red Indian sandstone. Although theroom is not climate-controlled, the architecture of the building and the locationof the room provide a comfortable and stable environment throughout the year.
The average temperature is 30 °C in summer and 20 °C in winter.

The cases were individually mounted on polished stainless steel bases, approximately 1 m in height, with varnished teak cabinetwork that covers the metalframes of the cases. The bases and cabinets were constructed at the NPL. A
trace-oxygen analyzer connected to a datalogger was installed in each nitrogenfilled case for monitoring oxygen leakage into it during performance evaluation.
The cases were initially flushed with dry nitrogen, and the oxygen content was
reduced to below 1000 ppm. The amount of oxygen leaking into the cases
was 5 cm3 (50 ppm) over a seven-month period for one case, and 109 cm3(1130 ppm) over a three-month period for the other. Appropriate amounts ofan oxygen scavenger (Ageless) will be placed in the cases to keep the oxygen
level as low as required. The performance of the cases was accepted by both the
NPL and the GCI.

Summary
Two hermetically sealed, inert-gas-filled display and storage cases were designed
and fabricated by the GCI to preserve the Constitution of India. The cases weresuccessfully installed in a non-air-conditioned room in the Library of the Parliament House in New Delhi. After one year of joint testing in situ by the library,
the NPL, and the institute, the cases have been accepted as effective for theconservation and display of the Constitution of India.
The cases are designed to maintain a nitrogen microenvironment of less than
1% oxygen concentration at 45% relative humidity (RH) for a minimum of
twenty years without the support of a mechanical or electrical subsystem or
maintenance. This microenvironment has been chosen to prevent oxidation,
biological and microbiological deterioration, and air-pollution damage to the
document.
The ceremonial placement of the Constitution of India took place on 27 October
1995.
Preservation of Original Documents57

Acknowledgments
The authors wish to thank Miguel Angel Corzo, director, and Neville Agnew,group director, Information and Communications, of the Getty Conservation
Institute for their direction and encouragement of the project. Thanks also to
E. S. R. Gopal, then-director of the National Physical Laboratory (NPL); andA. P. Jain, then sub-director of the NPL, for their contributions. The authors also
wish to acknowledge the participation of the following individuals at the GCI:
Jim Davies, machine shop supervisor; Frank Lambert, consultant; Kevin Fennelly,
student intern; and Vinod Daniel, former research fellow.

The National Physical Laboratory wishes to acknowledge the following individuals for their contributions: S. K. Joshi, former director of the NPL; O. P. Agrawal
and I. K. Bhatnagar, former directors of the National Research Laboratory forConservation of Cultural Property, Lucknow, India; D. G. Suryawanshi, seniorscientific officer of the National Research Laboratory; Georges Amsel, Laboratoire de Physique des Solides, Jussieu, Paris; P. Averbuch, Centre National de laRecherche Scientifique (France), Grenoble; Regis Ballestracci, former deputy
scientific counselor of the French Embassy in New Delhi; K. S. Bhandari, scientist,
Forest Research Institute, Dehradun; R. C. Bhardwaj, the Secretary General;
A. N. Kaul, G. C. Malhotra, and S. K. Sharma, former directors, John Joseph,director, and R. K. Chadha, joint director, Parliament Library, New Delhi;
J. Claude Lehmann, research director, Janes L. Barton, technical director, andtheir highly efficient team at Saint-Gobain, Paris; J. M. Pierrard, director, Paper
Research Institute, Grenoble; and Chandru J. Shahani, preservation research
officer of the Library of Congress, Washington, D.C.

References
Maekawa, S., and F. Lambert
1993

The Getty Conservation Institute's Inert Atmosphere Display and Storage Cases
for the Pharaonic Mummies of the Egyptian Museum, Cairo. Marina del Rey,
Calif.: The Getty Conservation Institute.
National Bureau of Standards (NBS)
1951
Preservation of the Declaration of Independence and the Constitution of theUnited States. Washington, D.C.: NBS.

National Research Laboratory for Conservation of Cultural Property
1994
Report on the condition of the Constitution of India, prepared for the Parliament
Library, Lucknow, India, September.

Chapter 6

58

Chapter 7

Preservation of the
Mummy of an
Egyptian Child in a
Hermetically Sealed
Museum Case in
Spain
Shin Maekawa

In the 1860s, Eduard Todà i Güell, the premier Catalonian archaeologist of theperiod, was attached to the Spanish Consulate in Cairo and working on projects
cooperatively with Egyptian authorities. In 1866, he was urged by Gaston
Maspero, his personal friend and the director of the Antiquities Service of Egypt,
to excavate the tomb of Sennedjem at Deir el Medina in Thebes (Belascoain andTrullen 1995). Although Sennedjem had not been a person of pharaonic rank,
this tomb was of particular significance because it was found to be intact andquite untouched by millennia of tomb robbers. Thus, during his careful excavations, Todà was able to discover invaluable information about details of thefuneral rituals of the New Kingdom, which are essential even today. From the
excavated objects, he assembled a collection of Egyptian antiquities that was
donated to the Biblioteca-Museu Víctor Balaguer in Vilanova i la Geltrú, Spain,
and the Archeological Museum in Madrid. Part of the collection in the Biblioteca-Museu is the mummy of a five-year-old child (25 cm wide and 83 cm long),
named "Nesi."

In 1886, Nesi was displayed in a glass case typical of the period (Fig. 7.1), in
the Egyptian collection of the Biblioteca-Museu (Belascoain and Trullen 1995).
Moved to another, similar case sometime in the last century, Nesi was againtransferred in 1988, this time to a custom-designed glass case with a massive
marble base (Fig. 7.2). The beauty of the new display hid several flaws: besides
continuing to be supported on a moisture-retaining cotton cushion, Nesi was
illuminated by a UV-rich fluorescent light directly above the case and thus wasunintentionally exposed to a new threat: photooxidation of the linen wrappingsof the mummy, which greatly increased their fragility.
In addition, during movement of this case, signs of insect infestation and a fungal growth were noted on the mummy. Unfortunately, at this time, in the 1980s,
there was a lack of consensus among Egyptologists in the world community
about the best methods of coping with such problems and of ensuring the longterm preservation of mummies. Extended search of then-current and past literature on the subject and many discussions with others gave Elena Bolívar, theconservator of the museum, no decisive course to follow. Finally, in 1991, she
was able to consult with Nieves Valentín, the research biologist at the Institutode Conservación y Restauración de Bienes Culturales (ICRBC) of the Spanish
Ministry of Culture for an evaluation of these problems and for their solution.
From 1987 to 1989, while working as a research associate at the Getty Conservation Institute, Valentín had been involved in studies dealing with insect andother microbiological controls using inert-gas atmospheres. On her return toFigure 7.1
Child Egyptian Mummy, Nesi, in display at the
Biblioteca-Museu Víctor Balaguer, Vilanova ila Geltrú, Spain. Courtesy of Biblioteca-Museu
Víctor Balaguer.

59

Spain, she had extended the research and implemented the findings in several
museums and libraries in Spain, and in Central and South American countries,
with marked success.

Conservation Treatments
After a survey of the mummy and the display environment, Valentín immediately
had the mummy, without its moist cushion, transferred to a large plastic bag,made from an oxygen-barrier film, through which a continuous flow of argon
was passed (Valentín 1992). By using this virtually oxygen-free environment
over the initial test treatment period of five weeks, she was successful in stopping the infestation and reducing the overall microbiological activity on themummy. For the next two years, the bag was purged weekly with argon tomaintain the oxygen content below 500 ppm while the relative humidity was
kept at about 45% (Valentín 1994). For permanent maintenance of the argon
environment, and so the mummy could again be displayed to the public,
Valentín recommended that the museum contact the GCI about obtaining a
GCI-designed hermetically sealed display and storage case for Nesi.

Fabrication of the Case
Figure 7.2

Nesi in the custom-designed display case,showing biodeterioration (Valentín 1994).
Photo by Nieves Valentín.

Following discussions with the GCI, the Biblioteca-Museu agreed to search for a
local display case manufacturer to coordinate the fabrication and installation of
the case. The GCI offered to provide free consultation throughout the project, inthe confident belief that any skilled display-case producer could fabricate thecase, given proper guidance. In addition, the GCI considered it to be especially
important for a Spanish institution to develop the competence to produce (or toarrange for the production of) the hermetically sealed case because ethnographic museums both in Madrid and in the Spanish Canary Islands own several
important mummies native to the islands (Guanches mummies, as they are
known), as well as Egyptian mummies. Clearly the preservation of these mummies is of great national cultural importance, and their maintenance in an inertgas atmosphere is a superior method for achieving this goal.
Additional reasons for having the sealed case made in Spain were the increased
cost and possible serious damage in transport if it were fabricated in the UnitedStates and then shipped to Spain. Although the case is adequately sturdy in anormal static state on display or in storage, the possible stresses that can occur
in commercial, unguarded shipment could permanently damage some of its
members so that a hermetic seal could never be regained. Further, because
skilled labor would be required for the installation and in situ testing of the caseat the Biblioteca-Museu, it was thought advisable that the persons actually
responsible for constructing the case be involved in its careful local transport andfinal setup. The experience of the Biblioteca-Museu should be valuable in the
future to all those museums needing to manufacture such cases in Spain andpotentially useful elsewhere.
In January 1993, Elena Bolívar of the Biblioteca-Museu discussed the local production of a GCI-designed hermetically sealed case with Joan Ramon Aromí
Folch of Metode Company, a Barcelona firm that prepared and installed museum
exhibits. Metode agreed to coordinate the project (Aromí Folch 1994; Aromí
Folch and Argemí Torras 1996) and—after extensive negotiations with several
organizations, principally the Serveis Cientifics Tècnics de la Universitat deBarcelona (SCTUB), an industry-university collaborative group of the Universityof Barcelona—it finalized a contract with all parties in September 1993. The
SCTUB would machine some of the metal components, obtain others, fabricate
the bellows, assemble and test the airtightness of the case and its accessories,
and install it in the museum. A local exhibit designer would be responsible for

Chapter 760the aesthetic design of the sealed case, including its base. The final plan
produced by the designer is shown in Figure 7.3.
The major challenges in case construction arose from the need for precision in
the manufacture of the metal components of the frame and in their assemblywith the glass faces. This precision is required for a near-perfect seal with theViton O-rings on which the glass is held to the frames (including their corners)by spring (pressure-retention) strips. To ensure exact placement of the O-rings
and ready retention of them during assembly, the frames are made from aluminum extrusions with a custom-designed cross section. Each of the eight corner
elements is novel in that it can be bolted to three frame components while providing smoothly connected surfaces for the O-rings of the adjacent glass faces.
To help expedite the project, the GCI provided the machined corner elements forthe case as well as all needed engineering drawings and descriptions of assembly
and testing.
To produce the die that could extrude aluminum with the cross section needed
for the case frame would have cost more than US$2,000 if the work had been
done in Barcelona. (The GCI has underwritten the cost of an extrusion die and asof 1996 the GCI can recommend a U.S. source that will inexpensively manufacture the extrusion.) In 1990-91, however, the Egyptian Antiquities Organization(now the Supreme Council of Antiquities) had purchased a large volume of the
extrusions from an aluminum-window manufacturer in Egypt for its use in constructing a GCI-designed hermetically sealed case for the Royal Mummy Collection at the Egyptian Museum in Cairo, and the EAO had extra extrusions forsale. Therefore, Aromí Folch was able to go to Cairo and purchase the needed
extrusions.
With these critical components in hand, Evelio Lantigua and Ferran Vilardell of
the SCTUB group were ready in early 1994 to combine them with other necessary units they had fabricated or purchased in Barcelona. These included the aluminum bottomplate (with a large access port and several small tubing ports forinert-gas entry and exit, and for bellows connections, as indicated in Fig. 7.3),
the glass sides and top, the Viton O-rings, and the essential retention strips thatwere screwed to the frames and provided the pressure to hold the glass faces
tightly to the O-rings. The case's exhibition designer provided a hidden compartment in the base of the finished display so the bellows and the oxygen monitor
Figure 7.3

Drawing of the exhibit design of the proposed
hermetically sealed display and storage case at
Bilblioteca-Museu Víctor Balaguer (Aromí
Folch 1994).

Preservation of the Mummy

61

would be invisible. The control panel for valves and humidification apparatus(described in the following paragraph) were similarly concealed in the base of
the final display.
Because argon gas is available only with an extremely low moisture content, andValentín had recommended that the mummy be kept in an environment whose
relative humidity level was about 45%, the argon to be used for flushing thecase had to be humidified to that level. This was achieved by a two-vessel system, as shown in Figure 7.4. Valve 2 was adjusted so the flow of dry argon
would mix with that of the nearly saturated argon coming from the vessel ofwater at the right to result in a 45% relative humidity level, as indicated by the
RH sensor in the mixing chamber.

Figure 7.4

Schematics of attachments to hermeticallysealed case's bottomplate (Aromí Folch 19943

1 = Nitrogen source
2 = Humidity control valve
3 = Three-way ball valve
4 = Mixing chamber
5 = HR sensor

6 = Security valve
7 = Three-way ball valve
8 = Manometer
9 = Bellows valve
10 = Bellows

11 = N2 out valve
12 = Microfilter
13 = Samples accessAn essential aid to the testing of the completed, sealed case and its accessories
was the loan of a trace oxygen analyzer by the ICRBC. The case was designed tohave a percent oxygen monitor, which has a resolution of 0.1%, at the range
between 0% and 25%, for monitoring the oxygen concentration in the casewhile being used for display. However, it was necessary to use a trace oxygen
analyzer, which has a resolution finer than 10 ppm (0.001%), during the determination of the leak rate at the installation. Purchasing the analyzer would
increase the project cost by US$10,000 (in the United States, as of this writing,trace oxygen analyzers cost $4,000 to $5,000) and the project would not be able
to support it. Leak testing by other techniques, such as halogen leak detectors,
can indicate only points of major leakage, not the extremely small amount ofoxygen leaking into the case per day that must be determined if the long-term
performance of the case is to be predicted.
As with any complex project, there were technical obstacles to be overcome, but
the effective collaboration of individuals in the several organizations involved
resulted in a case that fulfilled the original goals. After extensive testing, on
17 November 1994, the completed 384 I sealed case (55 cm high, 155 cm long,
Chapter 762and 45 cm wide) was installed in a non-air-conditioned storage building of themuseum while the museum was being renovated. Before the mummy was transferred to this case, a conservator from the ICRBC had treated the mummy's linen
wrappings and polychrome papyri (Herráez Martin 1994).
To present the project and discuss the use of inert-gas atmospheres for the preservation of mummies and other organic objects, a roundtable discussion wasorganized at Fundació Joan Miró in Barcelona by the foundation, BibliotecaMuseu Víctor Balaguer, the ICRBC, and Metode. Approximately eighty museum
professionals from both Spain and Portugal were in attendance, an indication of
the widespread interest in the subject and in the approach used by the participants in the project.
Figure 7.5
The Spanish-built, hermetically sealed display
and storage case for the child mummy, Nesi, in
the Egyptian gallery at Biblioteca-Museu
Víctor Balaguer.

Upon completion of the remodeling of Biblioteca-Museu Víctor Balaguer in early
1996, the hermetically sealed display case containing Nesi was reinstalled in the
Egyptian gallery for permanent display (Fig. 7.5). It has an argon atmosphere at
45% RH, and its performance is being determined by an oxygen monitor. The
case has been meeting the criteria for an excellent sealed unit, in that it has had
Figure 7.6
Members of the project team shown in frontof the Spanish-built, hermetically sealed display and storage case for the child mummy,
Nesi, in the storage building of BibliotecaMuseu Víctor Balaguer.

Preservation of the Mummy63

a leak rate of less than 4 ppm of oxygen per day since the installation. Twenty
packets of the Ageless Z-2000 oxygen scavenger (40,000 cc oxygen absorption
capacity) will be placed in the case, along with 10 kg of silica gel that has been
conditioned at 45% RH and 100 g of activated carbon, for 70 years of maintenance-free display in the museum.

Acknowledgments
The following people participated in the project: Josep Maria Trullen, director of
Biblioteca-Museu Víctor Balaguer; Ricard Belascoain, curator of BibliotecaMuseu Víctor Balaguer; Elena Bolivar, conservator of Biblioteca-Museu Víctor
Balaguer; Nieves Valentm, research biologist at the ICRBC; M. Isabel Herráez
Martin, conservator at the ICRBC; Joan Ramon Aromí Folch, Metode Company;
Ricard Andres, aesthetic designer for the case; and Evelio Lantigua and FerranVilardell of the University of Barcelona. Figure 7.6 shows these members of the
project.

References
Aromí Folch, Joan Ramon
1994

Adaptation of a showcase prototype design of the Getty Conservation Institute.
Internal report. Metode Company, Barcelona, Spain, November.

Aromí Folch, Joan Ramon, and Montserrat Argemi Torras
1996

Adaptation of a prototype showcase design in the Getty Conservation Institute,control of biological activity with an atmosphere of inert gas. Report, HC-Spain,
November.
Belascoain, Ricard, and Josep Maria Trullen
1995

Letter to the author. Biblioteca-Museu Víctor Balaguer, Vilanova i la Geltrú.

Herráez Martin, M. Isabel
1994

Informe sobre el trabajo de conservación preventiva realizado en una momia
egipcia. Internal report. Instituto de Conservación y Restauración de Bienes
Culturales, Madrid, December.
Valentín, Nieves
1992

Contaminación biológica y tratamiento de la momia egipcia perteneciente al
Museo Balaguer de Vilanova i la Geltrú. Internal report. Instituto de Conservación y Restauración de Bienes Culturales, Madrid, December.
1994
Análisis de contaminacion biológica de una momia egipcia del Museo Balaguer
expuesta a atmósferas inertes. Internal report. Instituto de Conservación yRestauración de Bienes Culturales, Madrid, December.

Chapter 764IndexA

C

Abe, Y., 37

Cairo, environmental conditions of, 1
Calmes, A., 10
carbon dioxide fumigation, 18
cellulose
deterioration of, 8-9
oxygen-free environment for, 7-8
Cerambycidae, 18
Charters of Freedom of the United States,
storage of, 7-8, 10
chromatography, 10
cigarette beetle, 18
climate controls, 31
collagendeterioration of, 9-10
and humidity, 12
oxygen-free environment for, 7-8
preservation of, 9color fading, 9light and, 7
Constitution of India, 53f
description of, 53
display case for, 53-58, 55f, 56f, 57f
backplate of, 56f
and collaboration between NPL and GCI,

acid, in cellulose, 9
acridine orange, 23
Actinomyces sp., 20, 21f, 24, 25f"Action of Light on Water Colors" (Russell and

Abney), 7
activated carbon, 50
aerobic organisms, control of, 20-21
Ageless, 35-37, 39f, 40, 57

reaction rates of, 3Agnew, N., 5
Ajie, H., with Sobel, 10
alcohol, 17
Algueró, M., 19with Valentín, 17

aluminized polyethylene, 34

aluminum rods, in display case construction, 33
aluminum-plastic bellows, 39f
ammo acid analysis, 10
anaerobic organisms, 21-23
animal skin. See parchment
Anobiidae, 18
Anobium punctatum, 18, 19f, 20f
Argemí Torras, M., with Aromí Folch, 60

argon anoxia, 18, 20f, 24, 26, 62

Arney, J. S., 9
Aromí Folch, J. R., 60
Artsorb, 37
Aspergillus flavus, 20, 21f
Aspergillus niger, 20, 21f
Aspergillus sp., 24, 25f
Attagenuspiceus, 18, 19f

B
Bacillus sp., 20, 21f, 24, 25fbacterial growth, 17
control of, 19-23
Bailey, S. W., 17
Banks, H. J., with Bailey, 17
Barraco, R. A., 11
Belascoain, R., 59
bellows, 3-4, 31, 34-35, 39f, 43

Biblioteca-Museu Víctor Balaguer,
Spain, 23
mummy display case for, 59-64
Bogaard, J., with Whitmore, 8
Bolívar, E., 59, 60

Bose, Shri N. L, 53
Bouchard, J., with Zou, 8Brommelle, N. S., 7
Brown, D., with Passaglia, 8, 31
Bulst, W. A., 8
Burton, D. M. B. E., 10
butyl, 31

65

54-55

construction of, 54
design of, 55-56
fabrication of, 55-56
installation of, 56-57
with O-ring seal, 55f
Constitution of Puerto Rico, storage of, 8Constitution of the United States, storage of,
7-8, 10
Cryptotermes brevis, 18D
Daedalea biennis Fries, infestation ofRamses II mummy, 1
Daniel, V.
with Hanlon, 18
with Lambert, 37
David, A. E., 8
Dead Sea Scrolls
deterioration of, 10-11
preservation of, 10
Declaration of Independence, storage of,
7-8, 10Dermestidae, 18
Derrick, M., 10
deteriorationcase studies of, 9-12
causes of, 1
of cellulose, 8-9
extent of, 10-11
inert gases for control of, 17-29

in presence of oxygen, 8-9protection from, by oxygen reduction, 7-15
of Whatman filter paper, 8
Dickens, B., with Passaglia, 8, 31
display and storage case, hermetically sealed
bellows of, 34-35
bottom plate of, 38f
construction of, 33-39
corner assembly, 36f
corner element, 35f
design and construction of, 31-45
design concepts for, 32
display section of, 33-34
evaluation of, 40-41

extrusion end, 36f
extrusion profile, 34f
general description of, 32-33
hermetic seal of, 37f
installation of, 40-41

leak testing of, 40
materials and suppliers for, 42-43
for Nesi, 59-64
oxygen scavengers in, 35-37
passive control agents, 35-39
pollution sorbent of, 39
prototype of, 32f
purging of, 40-41, 41 f
recommendations for, 49-50
relative humidity buffer of, 37-39
retention strip of, 38f
for Royal Mummy Collection, 47-52
di-tyrosine, in parchment, 10
Donahaye, E., 17
Drosophila melanogaster, 18
drugstore beetle, 18dyes, fading of, 9dynamic system, 31

E
EAO. See Egyptian Antiquities Organization
Egyptian Antiquities Organization (EAO), 2,

20, 47, 51f, 61. See also Supreme

Council of Antiquities
Egyptian Museum, Cairo, 47, 47f

Royal Mummy Collection of, preservationof, 1-5, 11
Royal Mummy Room of, 47f, 50f, 50-51, 52
closing of, 1-2
Elert, K., with Maekawa, 40
Emancipation Proclamation, storage of, 8ethylene oxide, 17
ethylene vinyl alcohol-laminated film, 34

F
Feller, R. L, 7, 8, 9
fibroin, 9

Index

66

Filmpak 1193, 34

Fleurat-Lessard, F., 17
Florian, M. L. E., 17
France-Lanord, A., 8
with Salins, 8
fumigants, 17
Fundació Joan Miró, 63
fungal growth, 17
control of, 19-23
furniture beetle, 18G
Gallo, F., 21
gamma radiation, 17
gasket technology, 31
Gates of Paradise, preservation of, 8GCI. See Getty Conservation Institute
Getty Conservation Institute (GCI)
biodeterioration studies, 17
collaboration with National PhysicalLaboratory, 54-55
and Egyptian Mummy Collection, 2, 3
and fungal/bacterial control, 20-21
and parchment preservation, 10
Ghiberti, Gates of Paradise by, 8
Gifford, J., with Pääbo, 17
Gil-Av, E., with Weiner, 10
Gilberg, M., 18
Ginell, W. S., with Schilling, 10
Grosjean, D., with Parmar, 39
guanches mummies, 60
Guell, E.T., 59

Gurnagul, N., with Zou, 8H
Hanlon, G., 18

Hansen, E., 3, 9, 10, 11, 23
with Sobel, 9Hariri, F., with Sobel, 9helium, effect on parchment, 8, 10
Herráez Martin, M. I., 63
Heuser, E., 8
Hewlett, M. J., with Sobel, 9histidine, in parchment, 10
Hoshino, J., with Nakamura, 17
house longhorn beetle, 18
humidity, 3. See also relative humidity
Hutchinson, F., 17
Hylotrupes bajulus, 18, 19f, 20f

I
ICRBC. See Instituto de Conservación yRestauración de Bienes Culturales

inert gases
for biodeterioration control, 17-29
dynamic system with, 31
static system with, 31

insect pests, control of, 17-29

Mavalankar, Shri G. V., 53

Instituto de Conservación y Restauración deel Medina, S. D., 59

Bienes Culturales (ICRBC), 17, 59
Instituto del Patrimonio Histórico Español,
3, 17
iron oxide, and color fading, 9Iskander, N., with Nakhla, 1Israel Museum, 10

mercuric sulfide, and color fading, 9Merovingian belts, storage of, 8
Merovingian helmet, storage of, 8
metalsoxygen-free environment for, 7-8
preservation of, 8Jmethionine, in parchment, 10
methyl bromide, 17

Jacobs, A. J., with Arney, 9Jay, E., with Navarro, 17

K
Kanagy, J. R., 8
Kenjo, T., 9, 17
Kennedy, J., with Rust, 1, 18

Kishan, Hari, 54
Koestler, R., 9, 17, 18

Kondoh, Y., with Abe, 37
Kowalik, R., 19
Koyano, M., with Toishi, 31
Kuhn, H., 7
Kustanovish, Z., with Weiner, 10L
Lambert, F., 5, 37

with Maekawa, 26, 31, 55
Lantigua, E., 61
Lasioderma serricorne, 18, 19f, 20f
lead oxide, and color fading, 9leak testing, of display and storage case, 40
Leary, G. J., 9
leather, deterioration of, 8Lee, S., with Hansen, 10, 23
Library of Congress, 10
light
and color fading, 7effects ofon cellulose, 8-9
on organic materials, 3in vacuo, 7Lightsense Corp., 4
lignin, deterioration of, 9
Lindstrom, M., with Valentín, 1, 10
litharge, fading of, 9
Lyctidae, 18
Lyctus brunneus, 18, 19f

M
Maekawa, S., 26, 31, 40, 55
with Hanlon, 18
Martin de Hijas, C, 19
with Valentín, 17
Marvelseal 360, 34
Maspero, G., 59

Index

67

Metode Company, 60

Mitsubishi Gas Chemical Co., 37
molecular sieves, 37
Mucor, 24, 25f
mummies. See also Egyptian Museum, Cairo;
Nesi; Royal Mummy Collection
biodeterioration control of, case study,
23-26, 24f, 25f, 26f

fungal and bacterial infestation of, controlof, 20-23, 21f, 22f, 23f

preservation of, 9, 11
rehydration of, 11
storage of, 8water-absorption curves of, 11
Musée Archéologique of Strasbourg, 8Musée de l'Homme, Paris, 1
Museo Opificio del Pietre Dure, Florence, 8N
Nakamura, H., 17
Nakhla, S., 1
Nakht Rom I, mummy of, 11
National Bureau of Standards (NBS), 7-8, 10,
31, 54
National Gallery, London, 7
National Physical Laboratory (NPL), 54
collaboration with Getty Conservation
Institute, 54-55
National Research Laboratory for Conservationof Cultural Property, 53-54
Navarro, S., 17
NBS. See National Bureau of Standards
Nehru, P. J., 53
Nesiconservation treatments for, 60
display case for, 59f, 59-64
argon in, 62
bottomplate attachments to, 62f
construction of, 61
cost of, 62
design of, 61f
extrusions of, 61
fabrication of, 60-64
installation of, 63
O-rings of, 61

project team of, 63f
trace oxygen analyzer in, 62
Newman, R., with Arney, 9
Newton, J., with Smith, 17

Nicobium castaneum, 18, 19f

Nikolaev, G., with Petushkova, 23
nitrogenfor color fading, 9and light-sensitive colors, 7
for linen storage, 8
for metal storage, 8
for paper storage, 8nitrogen anoxia, 17, 18, 20f, 26
Noble, P., with Koestler, 9, 17
NPL. See National Physical LaboratoryO
organic dyes, fading of, 9organic materials, deterioration of, causes of, 1
O-rings, 31, 33, 55f, 61
ortophenyl phenol, 17
oxygenand deterioration, 7-15
and fungal/bacterial growth, 22f
oxygen absorbers, 3
oxygen scavengers, 35-37, 39f
oxygen sensor, 34P
Pääbo, S., 17
paper
deterioration of, 9
oxygen-free environment for, 7-8
parchment
deterioration of, case studies of, 9-11
oxygen-free environment for, 7-8
preservation of, 9Parliament Library, India, 53
Parmar, S. S., 39
Parreira, E., with Koestler, 9, 17
Passaglia, E., 8, 31
Penidllium, 24, 25f
Penidllium commune, 20, 21f
pentachlorophenol, 17Petushkova, P., 23
pigments, fading of, 9pleated Teflon (PTFE) membrane filters, 40
Plexiglas
in argon treatment, 25f
for metal storage, 8Pogrund, R. S., with Sobel, 9
pollution sorbent, 39
polyisobutylene, 31
Poole, J. B., with Burton, 10
Preservation Capsule, 8pressure-relief valve, 34

Index

68

Preusser, R, 5
with Lambert, 37
with Maekawa, 26
with Valentín, 1, 10, 18
proteins, preservation of, 9PTFE. See pleated Teflon membrane filters

R
Raizada, Shri P. B. N., 53
Ramses II, mummy of, conservation treatmentof, 1Ravenel, N., with Hanlon, 18
red vermilion, fading of, 9Reed, R., with Burton, 10
rehydration, of mummies, 11
relative humidity (RH)
and collagen, 12
and fungal/bacterial growth, 21, 22f
ideal level of, 3
and parchment, 10-11
relative humidity buffer, 37-39
relative humidity sensor/transmitter, 34
RH. See relative humidity
Rogers, G., 5Royal Mummy Collection
closing of, 1-2conservation of, 1-5
display case for, 4f, 47-52, 50f
construction of, 47-50
cost of, 47
design of, 3-5
exploded view of, 48f
extrusions of, 48
fabrication of, 3-5
modifications to, 48-49
oxygen leak rate of, 4project development, 2-3
proposed storage conditions, 3
retention strips of, 48-49
schematic drawing of, 49f
size of, 49
preservation of, 11
Royal Mummy Room, 47f, 50f, 50-51
mummies in, 52
Russell and Abney Report of 1888, 7
Rust, M., 1, 18

S
Saccharomyces rouxii, 21
el-Sadat, Anwar, 1-2
Saint-Gobain Company, 54
Salins, E., 8
Santoro, E., with Koestler, 9, 17
Schilling, M. R., 10
SCTUB. See Serveis Cientifics Tècnics de la
Universitat de Barcelona

sericin, 9Serveis Cientifics Tècnics de la Universitat deBarcelona (SCTUB), 60
Shroud of Turin, storage of, 8
sienna, fading of, 9silica gel, 37
silicone sealant, in display case construction,
33
silk, 9silver-soldering technology, 31
Smith, C, 17
Sobel, H., 9, 10
with Hansen, 9, 10, 23
sodium salt, 17
sodium salt p-chloro-m-cresol, 17South Kensington Museum, 7Stachybotrys, 24, 25f
static system, 31
Stegobiumpaniceum, 18, 19f
Stillings, R. A., 8
Streptococcus sp., 21f, 24, 25f
Streptomyces sp., 20, 21f, 24, 25f
sulfuryl fluoride, 17Supreme Council of Antiquities, 1, 2, 5, 47, 61.
See also Egyptian Antiquities
OrganizationT
temperature, 3effect on insect mortality, 18, 19f, 20f
and hermetic seals, 31
temperature sensor, 34
tetralkylammonium salts, 17Thomson, G., 39
thymol, 17
Toishi, K., 31
toxic cresols, 17
trace oxygen analyzer, 62
Traub, W., with Weiner, 10

Index

69

Trullen, J. M., 59
tyrosine, in parchment, 10

U
Uesaka, T., with Zou, 8
Ulodadium, 24, 25f
ultraviolet radiation, effect on cellulose, 8
University of Turin, 8
U-tube manometer, 34Vvacuuming, 17

Valentín, N., 1, 3, 10, 17, 18, 19, 23, 59-60,
62
Van Nostrad, R. J., with Stillings, R. A., 8
vellumand humidity, 10
preservation of, 9Vikane, 17Vilardell, R, 61

W
water-absorption curves, of mummies, 11
watercolors, fading of, 7, 9
Weaver, K. R, 8
Weiner, S., 10
Weintraub, S., 5, 39
Whatman filter paper, deterioration of, 8
Whitmore, P. M., 8
Wilson, A., with Pääbo, 17

X
Xestobium rufovillosum, 19f

Yyeasts, 21Z
Zou, X., 8

Index70

About the Authors

Eric F. Hansen is an associate scientist who joined the Getty Conservation Institute in 1985. He received his M.S. in organic chemistry from the University ofCalifornia, Irvine, and is currently pursuing studies of architectural sculpture of

the Ancient Maya at the University of California, Los Angeles, as a C. Phil, inarchaeology. His research interests include the deterioration of natural materials,
the factors affecting the treatment of painted objects, and the properties ofpolymers used in conservation. He was chair of the American Institute forConservation of Historic and Artistic Works (AIC) subgroup on Research andTechnical Studies in 1993 and became a fellow of the AIC in 1992.
Nasry Yousef Iskander received his B.S. degree in physics and mathematics fromthe University of Alexandria in 1965, and has expertise in practical machining
and woodwork. He has been the general director of conservation of theEgyptian Antiquities Organization (now Supreme Council of Antiquities) since
1984, as well as chief of the Conservation Laboratories of that organization
since 1980.

Hari Kishan received his M.S. degree in physics from Kurukshetra University,
India, in 1971 and his Ph.D. in low-temperature semiconductor physics from
Delhi University in 1986. In 1973, he joined the National Physical Laboratory(NPL) in New Delhi, where he has been participating in research and development work on low-temperature, solid-state physics and applied cryogenics. He is
now a senior scientist at the NPL and a life member of several scientific professional societies. He received an award from the Indian Cryogenic Council in
1985 for his work in applied cryogenics and has published more than forty
research papers in journals and conference publications. His research interest isin the field of cryogenics, preservation of national heritage objects, and humidity
measurements. He is presently engaged in establishing a National Humidity
Standard at the NPL.
Shin Maekawa received his M.S. degree in mechanical engineering from the
University of California, Los Angeles, in 1978. Since 1990, he has been a seniorscientist at the Getty Conservation Institute, where he has been conducting
research on the microenvironment of display and storage cases as well as
environmental monitoring at various archaeological sites.
Nieves Valentín received her Ph.D. in biological sciences from the Universidad
Complutense, Madrid, and joined the Spanish Ministry of Culture in 1973. Since
1987, she has been a research scientist at the Instituto de Conservación yRestauración de Bienes Culturales (now Institute del Patrimonio Histórico
Español) in Madrid. From 1987 to 1989, she was a research associate at the
Getty Conservation Institute, where she developed projects on the biodeterioration of museum collections and the application of new deinfestation methods forthe conservation of historic collections. Her research activity focuses on newtechnologies applied to the analysis of alterations to cultural materials. Since
1989, she has collaborated on investigations related to the biodeterioration ofmonumental stonework and historic stained glass.

71