By Janet Bridgland
Much of what we call cultural heritage falls into the category of objects and collections. For that reason, the conservation of objects and collections has been a focus of GCI research and training from the Institute's earliest days.
Traditionally found in museums, the artifacts and works of art that compose collections are often referred to as movable cultural property because they have been removed from their original context—as opposed to immovable cultural property such as archaeological sites and historic structures. In some instances, collections of movable cultural property concentrate on a particular type of object or highlight a diversity of cultures and time periods. In either case, they provide an important perspective on humanity's cultural development. Collections contain works of art such as paintings, drawings, and sculpture; functional objects including ethnographic materials and everyday household items; or natural history samples ranging from birds and mammals to botanical and geological specimens. They typically encompass a wide spectrum of natural and man-made materials—materials that present a variety of preservation challenges.
Although we understand the composition and behavior of many materials found in museum collections, numerous questions remain. For instance, while extensive research has been carried out on the conservation of paintings on canvas, identification of some artists' materials has proved a challenge. One difficulty has been accurately identifying the binding substances that have been mixed with pigments to create particular paints. Through its scientific research, the GCI has developed and refined a number of techniques to identify specific binding media. Another problem related to paint conservation has been the lack of a satisfactory means for consolidating flaking paint surfaces on ethnographic objects without altering their appearance or authenticity. Working with ethnographic conservators, the Institute initiated an investigation of the problem that ultimately led to several publications, a training course, and the development of a low-cost kit for identifying organic materials in paint. Materials and methods research at the Institute has also included the evaluation of various protective coatings used on museum objects.
Maintaining a stable museum environment helps limit the deterioration of objects, which is why the GCI advocates preventive conservation, which involves stabilizing entire collections by eliminating or modifying conditions that foster deterioration. It encompasses an understanding of such things as the effects of a museum's heating, ventilation, and air-conditioning systems on the stability of objects; the permeability of the building itself to outdoor pollutants; and display and handling practices. For the care of collections, preventive conservation is the most effective use of limited conservation resources.
The GCI has conducted wide-ranging research on the museum environment—from energy conservation and climate control to pollution monitoring and mitigation—to support preventive conservation efforts. The results of this work have been communicated to the field through publications and preventive conservation courses. In some instances, scientific work in one direction has led to developments in another. For example, GCI research into oxygen-free storage cases for the Royal Egyptian Mummy Collection led to the testing of a safe and effective means of pest eradication for museum objects.
External natural forces can also endanger collections. Collections in flood plains or hurricane paths may be water damaged beyond repair. Those in earthquake-prone areas can be reduced to rubble in seconds if they are not properly secured. From its inception the Institute has been concerned with disaster preparedness, and among its first research efforts was a series of studies to analyze and develop techniques for protecting museum objects during earthquakes.
In studying and developing solutions to the conservation problems of objects and collections, the GCI has sought to employ new and often sophisticated technology—such as the electron microscope—in its investigations. At the same time the Institute remains cognizant of the limited resources most institutions have available for conservation needs. Therefore, as part of their research, Institute staff have worked on low-tech and practical methods for dealing with conservation problems.
The GCI's philosophy in setting priorities regarding objects and collections is consistent with its overall approach to the broad range of conservation issues. Projects are selected according to the urgency of an existing conservation problem, its importance to the conservation field as a whole, and the absence of past or current research on a given topic. The Institute's work continues in such areas as the analysis of artists' materials and the issues of the museum environment—as does the dissemination of its findings through publications and courses.
Former Documentation Program Director
Throughout the ages a variety of substances, such as oils, egg, waxes, natural gums, and resins—alone or in combination—have been mixed with colorful pigments to prepare paints of different colors and hues needed for the creative expression of an artist. While not as diverse as pigments, these so-called binding media, making up about 10 to 30 percent of a paint, are much more complex. Most are natural materials that have been treated in different ways to alter their properties. Typically, they are prone to chemical and physical change over time—which, as in the case of medieval paintings, can be a half dozen centuries or more.
Analyzing the composition of paint layers is an important first step for a conservator working on the cleaning or restoration of a painting. However, in order not to damage a painting, conservators take only an exceedingly small paint sample to analyze—at most, an amount the size of a grain of sand. There are a number of modern analytical techniques that can successfully identify small paint pigment samples. Unfortunately, the identification of binding media in paint is a much more difficult task.
In the late 1980s, when modern methods for analyzing binding media were just beginning to be explored, the Analytical Section of the GCI's Scientific Program started developing the needed methodologies. Work began in 1989 with an extensive review of conservation science and analytical chemistry literature. Based on this review, several promising methodologies were targeted for further research.
The initial effort focused on the use of advanced instrumentation. However, it was recognized that developing only high-tech methods would not serve the field properly. Because many museum laboratories lack the resources to take advantage of sophisticated instrumentation, it was important to develop low-tech, low-cost, and user-friendly methods that could be used widely within the art conservation community. With this in mind, the Institute developed a kit using medical diagnostic technology for identification of the major binding media types encountered during conservation of ethnographic art objects. To complement this work, the Institute developed and improved thin-layer chromatography tests for the detection of binding media components.
A variety of other methods for analyzing binding media have also been researched; these include advancing the use of infrared microscopy for the study of painting cross sections; analytical strategies for differentiating very similar proteinaceous bindings, to distinguish between, for example, a whole egg and egg yolk only; using an elemental analyzer for very accurate determination of carbon, hydrogen, nitrogen, and sulfur in binding media samples; and using a sophisticated separation process in combination with gas chromatography-mass spectrometry to identify major and minor components of a small paint sample, as well as obtain information about binding media recipes and processes used by an artist when preparing paint. All this research contributed to the development of a methodology for radiocarbon dating of paint layers, a technique critical for authentication of paintings, drawings, prints, and other art objects that contain organic material.
The Binding Media Project was based on collaboration and exchange within the research group and with many experts in conservation science and analytical chemistry. The involvement of the GCI's colleagues from the J. Paul Getty Museum conservation laboratories also made the project possible.
Head, Analytical Section, Scientific Program
Preventive conservation is any measure that prevents damage or reduces the potential for damage. Rather than focusing on treating individual objects, a preventive conservation strategy emphasizes the management of the environmental factors that can affect collections—from the functioning of heating and air-conditioning systems to the materials used in constructing storage or exhibition cases. Because it works to improve the overall environment in which collections are kept, it is the most efficient, long-term use of resources for museums. With a comprehensive preventive conservation program in place, the need for individual treatments of objects—while not eliminated—can be reduced.
To encourage a preventive conservation approach, the Getty Conservation Institute since 1990 has offered a two-week course entitled "Preventive Conservation: Museum Collections and Their Environment." Designed for senior conservators and conservation scientists who work in museums, libraries and archives, regional conservation centers, and training institutions, the course updates participants' technical knowledge of preventive conservation and helps them consider effective ways to introduce preventive conservation policies and practices into their institutions.
Preventive conservation is collaborative in nature. Beyond developing preventive conservation policies, conservators must be skillful advocates of those policies, working both with other museum professionals and with external specialists such as architects, designers, engineers, and building contractors. The GCI course therefore stresses the practical aspects of communicating and collaborating with colleagues to improve collections care.
While the course was originally designed with a North American audience in mind, participants—now numbering over 140 from a wide range of institutions—have included conservators from Europe, Latin America, Australia, and New Zealand. In 1993 the GCI held the course outside of Los Angeles for the first time. In partnership with the Conservation Unit of the Museums and Galleries Commission of the United Kingdom, it offered the course in London for conservators and restorers from Britain and other parts of Europe. The Institute typically seeks a partnership with a local organization whenever it offers a course outside of North America. This local partner works with the Institute to identify particular training needs and to develop a program that addresses those needs.
In June 1995 the GCI offered its second course in London in partnership with The Museums and Galleries Commission. In November 1995, in cooperation with Mexico's Instituto Nacional de Antropología e Historia, it offered its first preventive conservation course in Latin America. Held in Oaxaca, Mexico, for conservators and conservation scientists from Latin America, the course focused on the specific needs of the region.
Senior Program Coordinator, Training Program
It has long been recognized that exposure to atmospheric pollutants constitutes a risk to museum collections. Outdoor pollutants produced by fossil fuels can damage paintings, textiles, and other works of art. Indoor pollutants generated by building materials can harm metal objects as well as other items.
To help institutions reduce these threats to their collections, the Institute began researching the problem of pollutants in 1985. The first two years of research focused on outdoor pollutants including nitrogen oxides, ozone and other photochemical oxidants, sulfur dioxide, and particles. In 1987 research expanded to include indoor-generated pollutants—specifically, formaldehyde, acetaldehyde, and formic and acetic acids. At the same time, the emphasis of research shifted from the macroenvironment (gallery and storage spaces) to the microenvironment (display cases and storage cabinets), where most of the damage from these indoor pollutants occurs.
Of increasing concern for collections in urban environments is the soiling of exposed surfaces, such as textiles, which cannot be cleaned safely or without difficulty. Internal combustion engines produce very small particles of nearly pure carbon, which cause extensive soiling. Part of the GCI research was aimed at determining how long it took for soiling to be visually apparent. Research found that perceptible soiling on vertical surfaces could occur as quickly as within 0.3 years within a historic house in Los Angeles with natural ventilation—or take as long as 18 years in a modern art museum equipped with mechanical particulate filtration. Knowledge of the time it takes for soiling to become visible allows collection managers to plan their preventive conservation strategy.
Institute researchers made use of recent technological advances in order to detect the low levels of pollutants found in museum environments (i.e., one molecule of pollutant in one billion molecules of air). A series of simultaneous indoor and outdoor measurements was taken at a variety of museums; the data provided a foundation for further research on the potential damage of pollutants and ways to mitigate that damage.
Studies were carried out to determine the damage gaseous pollutants cause to various types of museum objects. Certain photochemical oxidant pollutants proved detrimental to a number of organic colorants. In addition, various materials were exposed to formaldehyde to measure their sensitivity to the pollutant. These studies confirmed that metals—and to a lesser degree shells—were susceptible to formaldehyde. Yet glass and ceramic glaze were not affected after 100 days of exposure.
Recognizing the limited resources of many museums, researchers studied passive sampling devices that would allow museums to conduct their own surveys with minimal cost and expertise. Through testing, a number of commercially available, relatively low-cost products were identified that met the criteria for museum environments. This work has enabled many institutions to conduct economical pollutant surveys of their storage and display areas.
Also investigated were mitigation methodologies to reduce significant indoor concentrations of pollutants. Those methods that proved effective used active filtration, passive protection, and combinations of procedures that worked along with the building's ventilation system. The solutions are as simple as placing a tray of a sorbent material in a display case to absorb damaging pollutants or as thorough as identifying and isolating the offensive material from the display or storage space.
The large body of information amassed from this work has been detailed in numerous GCI publications and reports.
Cecily M. Grzywacz
Associate Scientist, Scientific Program
James R. Druzik
Conservation Scientist, Scientific Program
The longevity of most museum objects is determined by their environment. Large variations of temperature and relative humidity, as well as air pollution and high levels of illumination, cause many materials to deteriorate. An unsuitable environment can also encourage insect attack and fungal and bacterial growth on organic materials. However, these biological and microbiological assaults, as well as oxidation, can be eliminated if objects are kept in an oxygen-free environment, under chemically inert gases such as helium, argon, or nitrogen.
The efficacy of nitrogen environments for long-term storage of sensitive organic objects was first studied at the GCI between 1987 and 1989, as part of a project to develop a storage case for the Royal Mummies in the Egyptian Museum in Cairo. The GCI designed, built, and tested a nitrogen-filled, hermetically sealed prototype storage case for the mummies in 1989 and in the following years provided technical support and training for local Egyptian production of ten more cases, which were used when the Royal Mummy Room in the Egyptian Museum reopened to the public in March 1994. Two cases of the same design are now being used for the display and storage of the Constitution of India at the Parliament Library in New Delhi. With GCI technical guidance, the Biblioteca Museu Victor Balaguer, in Vilanova i la Geltrú, Spain, also built a case for an Egyptian mummy in its collection.
During the mummy case project, a nitrogen atmosphere was successfully tested for eradicating selected insects. The GCI then expanded the study, collaborating with the Department of Entomology, University of California, Riverside, to investigate exposure times required to kill 12 common museum insect pests using a nitrogen environment. Art objects were enclosed in nitrogen-filled bags fabricated from oxygen-barrier film. This proved very effective in eradicating insect infestation in just a week.
To disseminate the results of its research further, the GCI in 1994 conducted a one-week training course on pest management—with a focus on treatment by nitrogen anoxia, or oxygen deprivation—for almost 30 museum professionals from around the world. Because of the course's success, a similar course is planned in collaboration with the Museums and Galleries Commission of the United Kingdom, to be held in London in 1996 for museum professionals in Europe.
The use of nitrogen atmospheres with a very low concentration of oxygen to control pests has distinct virtues over methods relying on chemical fumigants, which contaminate objects, are hazardous to people, and harm the environment. Nitrogen has none of these disadvantages. Nitrogen environments are a safe, effective means to prevent museum objects from deterioration caused by biological factors and oxidation. To improve the practicality of the method, particularly in museums, libraries, and archives, the Institute is investigating the applicability of commercially available equipment for nitrogen anoxia treatment. A large-scale application of the method to mass treatment of artifacts is also being considered.
Head, Environmental Science, Scientific Program
Consolidation of Painted Ethnographic Objects
by Eric F. Hansen
Many of the indigenous technologies and materials used in the manufacture of ethnographic artifacts did not produce physically durable objects. Indeed, often they were not intended to endure. As a result, their conservation poses a series of challenges.
A particular problem for painted wood objects from Oceania and Africa is flaking or powdering matte paint—paint with a high ratio of pigment to binding medium. Because matte paint adheres poorly to the wood, it requires consolidation to prevent its continued loss. Unfortunately, using a consolidant can lead to discoloration or darkening of the paint. In 1988, recognizing this to be a major difficulty facing conservators of ethnographic objects, Scientific Program staff began addressing the problem through a series of studies. These were followed by the Training Program's development of a course for conservators on matte paint consolidation and, subsequently, the publication of an extended bibliography and review of the subject in a special supplement to Art and Archaeology Technical Abstracts (AATA).
Before solutions to the problem could be researched, it was first necessary to identify the technical difficulties associated both with the fragility of matte paint and with changes in the appearance of objects treated with consolidants. Then, through a review of the literature and laboratory testing, existing methods for treating matte paint were evaluated and several new methods developed. One outcome of this work was the binding media identification kit, a low-cost, low-tech kit for the identification of the wide range of organic materials used as paint binders in ethnographic objects. The results of the research were incorporated into a 1990 course on the consolidation of painted ethnographic objects, then later published in the Journal of the American Institute for Conservation. Additional research was done to learn how to re-treat objects whose appearance had been adversely affected by previous treatments.
A major product of the work of the past six years is the recently released supplement to AATA entitled Matte Paint: Its History and Technology, Analysis, Properties, and Conservation Treatment (with Special Emphasis on Ethnographic Objects). The supplement contains 1,125 abstracts of the periodical, monographic, and unpublished literature from disciplines such as anthropology, chemistry, coatings science, ethnobotany, and art history, as well as journals and monographs from the conservation profession. It includes an introductory overview with illustrations and a schematic presentation of the relationships between paint properties and treatments. The history, technology, and use of matte painted objects in various cultural and historical contexts is covered, not only in relation to ethnographic objects but also to paintings, painted architecture, contemporary art, folk art, and many other forms of applied art. This expansive viewpoint will be the format for a new course planned by the Training Program for early 1997.
Eric F. Hansen
Associate Scientist, Scientific Program
Seismic Damage Mitigation Techniques for Objects
by William S. Ginell
During an earthquake, damage to fragile objects on display and in storage in museums can be significant even if the building itself remains intact. Objects can overturn, fracture from stress, or collide with other objects or walls. An object's vulnerability to damage depends on many factors, including the earthquake's characteristics, the building's response, the material composition of the object, and the way it is supported. Although resistance to damage can be improved by modifying either the object or its support, altering the support, rather than the object, is preferred.
The development of techniques for mounting objects in museums located in seismically active regions has received little attention. Its relatively low priority as a conservation problem may be the result of the infrequency of earthquakes. In addition, a difficulty in tackling the problem is the wide variation in object characteristics that needs to be addressed in the design of mounting systems and the lack of guidelines that relate particular characteristics to earthquake damage.
Several years ago the staffs of the Conservation and Preparations departments at the J. Paul Getty Museum, recognizing these problems, initiated studies of mounting systems that would ensure survival of the Museum's objects in the event of an earthquake on the nearby Malibu Fault. The methods developed ranged from a sophisticated base isolation system that limits object movement to simple, unobtrusive tie-down clamps. It was important to quantitatively evaluate the performance of these systems under earthquake stress and to create engineering guidelines that could be applied to the design of mounts for specific objects in the collection.
Working with the Getty Museum and the Civil Engineering Department at the University of Southern California (usc), the GCI initiated a cooperative project to develop procedures for evaluating the response of individual art objects to seismic events. Because of the large variety of objects and support systems that required analysis, the research team developed generic object classifications and generic object-support-systems classifications. Analytical studies were carried out to model the systems, and a number of experimental tests were performed to determine the validity of the analytical models. Physical models of objects were subjected to simulated but realistic earthquake conditions on a computer-controlled shaking table.
Each of the most important ways in which museum objects respond to earthquakes was analyzed mathematically, and simple, easy-to-follow guidelines were prepared that allowed museum personnel to determine how a specific object would respond to a quake. The vulnerability of the object could then be assessed. Various generic methods for reducing vulnerability were proposed; these ranged from simply lowering an object's center of gravity or providing appropriately placed, firm attachments to support structures to more sophisticated techniques, such as base isolation.
The results of this pioneering study have been published both as a GCI report and in a conservation journal, making this important information available worldwide to museums located in high-seismic-risk areas.
William S. Ginell
Head, Monuments and Sites, Scientific Program