The environments in which collections are kept are affected by the conditions prevailing outdoors and by the will and ability to control the conditions indoors. The aim of environmental management Is to minimize the rate of degradation within the collections while not inadvertently compromising access to them. Problems arise from the complex interactions between objects, people, and their environments–problems that can have as much to do with politics and economics as with science and engineering.
Collection environments are never totally isolated but are part of a larger administrative system. Decisions made both inside and outside the immediate organization affect the management of the collection. While there are routine aspects of environmental management that can be carried out in relative isolation, decisions about planning, specifications, and the collection and communication of data require recognition of the complexity of the decision network and the way it changes through time.
The twentieth-century phrase "the museum environment" reflected a deliberately inward gaze, concentrating on a collection's immediate environment, and not on the wider environment outside the museum. The scientific methodology of isolating a small part of the system and reducing the number of variables studied enabled great progress in understanding the interaction between objects and their environments. The results of the individual pieces of research were easy to understand and reasonably easy to teach—but they could only be used with caution in decision-making. The work of twentieth-century pioneers who studied the collection environment left the conservation profession with a focus on the objects, concentrating on the proximate causes of change. The concept of the museum as an active enterprise was completely overlooked. This concentration on obvious local cause, rather than on networks of cause-and-effect relationships, persists in some current environmental recommendations and in collection risk assessment methodologies.
Focus on individual agents can lead to neglect of important synergies between potential hazards—for instance, light, pollution, and humidity. It can inadvertently lead to prioritizing one agent of deterioration over another of equal importance. Arguments about humidity tend to overshadow the effects of temperature, while a focus on proximate physical causes diverts attention from opportunities to address the involvement of people and their effects on the environment.
THE MUSEUM SYSTEM
In mid-twentieth-century discussions, the word "museum" usually referred to a large museum or gallery with nationally or internationally important collections. The word will be used here as a term for any building, of whatever size, housing a collection of objects that some believe have lasting significance.
The different professions that work in museums have ambitions and approaches formed by their specialized learning and practical experience. But despite different backgrounds and development paths that create distinct mind-sets, these separate museum tribes must collaborate to achieve common goals. The necessary communication can be made easier by a shared appreciation of the whole museum system. Broader understanding of the competing ambitions and complex interconnections can make the inevitable compromises more palatable.
The museum is a dynamic system that includes people and objects. Each object is part of a network that connects the collection, the building, visitors, staff, directors, funders, and politicians. The museum system interfaces with a world of constantly changing political and meteorological climates. The atmosphere surrounding the building alters daily and seasonally, varying over longer periods with the shifting patterns of pollution and the effects of climate change. The cities that house museums can grow rapidly or decline because of economic recession, natural disaster, or war. It is not possible to manage the collection environment without considering at least some part of this greater interconnected and dynamic system.
Some elements of the system have been understood for a long time—for instance, the role played by human beings in influencing decisions about museum environments. Humans have senses that can detect, and to some extent quantify, temperature and light. We seek comfortable temperatures that may be quite different from those outside the buildings we inhabit, and we value light because it enables us to carry out certain tasks. A great deal of technological innovation during the nineteenth and twentieth centuries was directed toward developing indoor environments with adequate temperature control and sufficient light for work and leisure activities. Temperature and lighting levels in museums are determined with human preferences in mind; this results in limits to how much they can be modified to favor the longevity of collections on display.
Humans complain when they are uncomfortable or inconvenienced. It is not likely that a scientific argument would succeed in convincing museum visitors that they really aren't that cold or that the lights really are bright enough. Even though it means consuming more energy and decreasing the lifetimes of collections, winter temperatures inside museums have been allowed to increase to satisfy visitor comfort. The early lighting recommendation of a 50-lux maximum for the display of sensitive objects has become a 50-lux minimum. No museum wants dissatisfied customers. During the 1980s, one large UK museum successfully ended visitor complaints by discreetly doubling the lighting level of its sensitive displays. They avoided criticism for flouting the prevailing strict guidelines by keeping this information to themselves until changes in conservation attitudes made it safe to divulge.
People are more sensitive to temperature than to humidity. In historic houses in northern Europe, it has become common to raise the ambient temperature to control the high humidity levels that might increase mold risk. This procedure may be difficult to maintain during the summer months as visitors complain about the heat (and the apparent waste of energy). Visitor comments have led to a reappraisal of target humidity levels rather than suggestions that the visitors just tolerate the discomfort for the sake of the collections.
MORE THAN MATERIALS SCIENCE
The science of materials is essential to understanding the interactions between objects and environmental factors such as light, pollution, temperature, and relative humidity. Environmental management is a part of preventive conservation, which relies on the prediction that a proposed action will decrease the risk of damage. Notions of prediction and risk introduce the concept of uncertainty. Uncertainty in the area of scientific interpretation refers to the variability of measurements. This variation can be treated mathematically, as the observations are recorded using numbers. The uncertainty that many decision makers face is not so easily quantified. Uncertainty may be due to lack of knowledge or ambiguity of language, or simply to the inability to see a clear difference between options that present mixtures of good and bad points. Defining damage is notoriously difficult. Definitions that rely solely on the scientific measurement of change are of limited use. The human appreciation of damage inevitably involves subjective estimation of changes in value and significance.
Conservation is about preserving items of cultural heritage so they can continue to be used for education and enjoyment, as reliable evidence of the past, and as a resource for future study. That is, they must be preserved for future generations without prejudicing the needs of those who want to enjoy them right now. The appropriate balance between present and future audiences can be informed by scientific understanding, but the final decision on distribution of benefit is one of ethics.
Take, for example, lighting policy. The debate on the rationing of light for display of sensitive objects has reached a quite civil level. The arguments can be couched in terms that reflect a scientific understanding of rates of fading and the limits of visual perception. Policies for rationing light-dose based on this understanding were published at the end of the twentieth century. However, at present these policies have been overtaken by approaches that include an assessment of the significance of the collection. Objective science has been supplemented by a subjective assessment of values.
The current lack of vocal disagreement on ways to ration light masks unresolved problems of variability and uncertainty. One approach to uncertainty is precautionary behavior—just play it safe. But you will not be thanked by current audiences if your present light levels or rationing protocols do not allow the appreciation of the objects today. You will not be thanked by future audiences if, when the box is ceremoniously opened in a hundred years, thermal decay has reduced the silk dress to tattered ribbons. More research might decrease the scientific uncertainty, but the predictions that would be necessary to argue for funding for this research or for improved storage rely on the continuation of the museum system in a stable and recognizable form.
A CHANGING WORLD
Management of the collection environment depends on decisions in other parts of the museum organization and on events outside the museum. In general, these factors are difficult to predict and are beyond the control of those in charge of collections. Thus they are often conveniently neglected. For short-term day-to-day decisions, this is not a problem. Over the long term, the impact of outside factors cannot be ignored.
Fashions in museum management can alter demands for environmental control as well as the will to finance it. The centrality of collections to the purpose of museums has been a topic of discussion in the professional literature. If collections are considered less important than the museum's immediate social or political role, why spend money on systems to extend their lifetime? A new museum director, for instance, hailed as a heroic leader, may want to sweep away all intellectual and physical barriers between the visitor and the exhibits, reflecting the attitude that constant change is the only way museums can remain sustainable.
On a national scale, ill will between states or factions affects foreign investment, international loans, and tourist numbers, all of which impact income streams needed by museums. On a global scale there are issues of climate change. Although the causes and extent of climate change can be disputed, it is difficult to deny that temperatures are increasing in parts of the world. In Europe there will be a decrease in the energy needed for heating in northern latitudes and an increase in energy needed for cooling farther south. The change in external environment will eventually mean that new hardware is required, as climate change affects energy consumption in museums. Shouldn't someone be planning for that need right now?
In the last half of the twentieth century, the major drive in environmental management was to install systems that tightly controlled climatic conditions throughout the building. The plant used energy in a way that was, at the time, both affordable and acceptable. However, within this century some museums have faced the choice of paying their energy bills or paying their staff. As green arguments gain popularity, there is more pressure on museums to justify using nonrenewable energy to preserve a few selected historic artifacts. Some museums have claimed exemption on the basis of their responsibility for unique collections of priceless heritage. In a political climate where "elite" has become a dirty word, they risk losing public sympathy.
The pressures of energy cost and sustainability are driving research. As a short-term measure, museums and archives are experimenting with turning off environmental systems for increasingly long periods and monitoring the changes. Other low-energy solutions to storage and display are being tried. Continuing debates about tolerable ranges of temperature and humidity have stimulated research into object vulnerability. The results will be welcomed if they show that currently recommended ranges can be broadened, especially if that leads to decreased energy demand.
THE KNOWN UNKNOWNS
There remain many things we don't know about object-environment interactions. If you look at the dates of publications on hazards such as indoor and outdoor pollution, insect pests, vibration, particulates, light, temperature, and humidity, you can observe time-related clusters that suggest a beginning, followed by dedicated research, and then a final conclusion for each topic. However, the fact that a subject has been previously studied, but is not being studied now, doesn't mean that knowledge in that area is complete. Clustering is often just an indication of insufficient data. There are limited numbers of research centers, all chasing limited funding. It is inevitable that fashion and the lure of novelty play a part in what is thought interesting, fundable, and publishable. While there is probably not going to be a revolutionary breakthrough that alters preventive conservation forever, there is a great deal of detail to be filled in. There is a need to determine the full extent of material susceptibilities and to understand mechanisms of change. And, of course, there is a need to relate this information to human perception and values.
One great advance would involve conservators, scientists, registrars, and curators agreeing on something like the allowable range of relative humidity for hygroscopic materials. There are several hurdles to overcome. One is that personal experience will always override scientific explanation. It's no use declaring that a set of circumstances is unlikely to cause damage if an individual is convinced that they have observed damage caused by those circumstances. The difficulty is that despite huge amounts of environmental data and assessments of object condition collected over the last few decades, there has been little success in correlating the two. Another hurdle is the immense variability in the material and structure of historic artifacts that share a common description, such as paintings or furniture.
The problem is having to construct a general rule from a finite number of observations and then to use this general rule to predict the behavior of individual items. That leads to the difficulty of dealing with exceptions to the rule. A well-devised series of experiments or a thorough epidemiological study can only provide results that have to be interpreted probabilistically. It is bound to be exhausting and expensive to guard against all possible events, rather than just the most probable. But ignoring the improbable tails of the probability curve means accepting the possibility of damage.
It is surprising in an age of instant global communication how slow and patchy the spread of new knowledge can be. One difficulty has been deciding how to frame the results of research and then find acceptable vehicles for dissemination. During the 1990s, researchers at the Smithsonian were criticized for publishing in materials science and engineering journals rather than in the mainstream conservation literature. Discussions have been less about what is the right thing to say and more about who has the right to say it. The furor over the recommendations of the Bizot Group early in this decade was a sign that many museum staff felt that their directors had no right to say anything about the preservation of objects in their own institutions.
Traditional means of communication, such as journals and conferences, are aimed at specialist audiences. Conference presentations are getting shorter, and journals are focused on novel results; there are rarely slots for historical perspectives or considered reviews of current thought. Outside the museum, the various tribes that need to work together do not go to the same conferences or read the same journals—this at a time when they should be learning a common language and sharing knowledge, which will involve finding ways to overcome concerns about losing specialist authority.
So where can the skills be learned? What are the options for successful dissemination of progress?
Courses taught at universities or online have to provide upto- date information as well as tools for thinking. Textbooks are time-consuming to write and expensive to buy. Usually published in a single language, a heavy book may not be the ideal dissemination vehicle. Textbooks rarely deal with all aspects of the museum environment in one volume. They favor either mechanisms of decay or methodologies for decision-making, but rarely both. An exception is Managing Indoor Climate Risks in Museums by Bart Ankersmit and Marc Stappers, 1 which deals with most of the component parts of the problem: the collection, its significance, the building, the hardware, and the visiting public. It accepts the elements of politics and economics and even gives a voice to the engineer.
Striking a balance between making a convincing argument and stressing the inevitability of uncertainty is difficult. Simple catchphrases such as "stable is safe" may be thought to convey an important concept, but they are dangerous if not followed by discussions on the great flexibility of the words used. It is necessary to explain the vagueness of the calculations used to promote concepts. It is important to learn that a precise-looking number often hides a range of probabilities. A straight-line graph is often shorthand for a diffuse cloud of data points. A better catchphrase might be "it's never that simple." A major shift is needed in the way preventive conservation is taught, allowing students to acknowledge complexity and uncertainty while learning when it is appropriate to use generalizations and when it is permissible to construct an individual solution that is relevant to a specific local case.
Jonathan Ashley-Smith was head of conservation at the Victoria and Albert Museum for twenty-five years and is currently a teacher, researcher, and consultant based in Cambridge, United Kingdom. He is the author of Risk Assessment for Object Conservation (1999) and served as secretary-general of the International Institute for Conservation (2003–6).
1. Bart Ankersmit and Marc H. L. Stappers, Managing Indoor Climate Risks in Museums (Switzerland: Springer, 2017).