CRITERIA FOR TREATMENT OF COLLECTIONS HOUSED IN HISTORIC STRUCTURES
4 SPECIAL TECHNIQUES FOR OBJECTS IN HISTORIC HOUSES
Collections in historic house museums need maximal protection from all environmental hazards, including temperature and RH, pollution, handling, vibration, light, and theft. Exhibition cases protect objects from gaseous and particulate pollution, theft, vandalism, ultraviolet light, and water leaks, as well as from fluctuations in relative humidity and flying insects. But they are inappropriate in historic houses, so it is necessary to incorporate as many of these functions as possible into conservation treatments. Clearly, treatments of collections housed in historic structures need to incorporate more protective techniques than treatments of collections housed in museum galleries. Some methods that may be considered unnecessary and therefore undesirable in a museum context will provide substantial protection for certain kinds of objects from certain hazards, but there are no methods for all materials or all sources of deterioration. Once the need for such methods becomes clear, it may be possible to devise additional protective techniques by adapting known materials and using them in novel ways. But some questions—such as the protective value and durability (as opposed to the chemical stability) of coatings—have been investigated only marginally in the past.
How different materials can be protected remains a difficult question. For paintings, wax-resin linings have been shown to be a reliable alternative to environmental controls and have the same positive effect on long-term aging as containerization. Younger conservators trained in major museums may have little experience in this technique and may never have seen paintings that have suffered from long periods of poor environments, but the evidence from research is unequivocal, and those conservators who have watched the behavior of wax-lined paintings over many years or decades will no doubt agree on their stability.
Wax linings can protect against damage from changes in relative humidity and from air pollution but not against light damage or heat damage from direct sunlight. Although conservators would always prefer that all ultraviolet and excessive visible light be kept out of interiors, we know that this ideal cannot be achieved. If there were a harmless way to provide ultraviolet protection by incorporating filtering materials in varnishes, for example, paintings on long-term exhibition certainly would benefit, as would furniture.
Other techniques are known to protect objects from pollution-promoted corrosion or from dust accumulation when the objects cannot be kept in exhibition cases. Benzotriazole, which prevents corrosion of copper, might be applied to bronzes in historic house museums. Conservator-applied spray coatings are probably indicated for polished silver and brass as well as for iron and other metals, although other measures for silver, such as frequent wiping or covering with Pacific Silvercloth, may be appropriate in some settings. The framing of textiles and works on paper should be carried out with the maximum possible seals and buffering materials inside and with UV-filtering Plexiglas. Plasters should be coated and painted, if this practice is acceptable, to prevent dirt from penetrating the pores and to aid in surface cleaning. Although stone sculpture is not usually coated, coatings might be considered for the same reasons. Wax coatings should probably not be used because of the difficulty of removing dust from the sticky surface, although the use of wax on furniture may have fewer undesirable effects than some other common coatings. Many customary household maintenance procedures, such as applying linseed oil polishes to furniture, putting saddle soap and leather dressings on leather, or bleaching linens, should be studiously avoided with historic materials. It may take a conservator's intervention to assure that this kind of traditional maintenance is not practiced.
Although furniture is a major component of historic interiors and its quality and importance in these settings may be proportionally greater than those of any other material, it is a relatively small part of museum exhibitions. Therefore, the field is perhaps less developed, and novel techniques or materials in furniture conservation are difficult to institute. The field of furniture conservation, once the realm of talented craftspeople who treated furniture for use by employing traditional techniques and materials, has become a real branch of conservation in which conservators adopt modern materials like Velcro and Acryloid B-72 to produce results suitable for exhibition in art museums. However, the number of people experienced in these new techniques is quite small compared to the number who treat paintings or other kinds of objects, and the range of treatment methods in use may still be quite narrow. Few techniques have been developed for protecting furniture from environmental fluctuations in nonmuseum settings although I understand that filling case furniture with large volumes of buffers has proved helpful.
Furniture conservators and others involved in preventive conservation matters should investigate the broadest possible range of ideas in order to find solutions. For example, if part of the problem with warping lies in the fact that exterior surfaces of case furniture are finished while interior surfaces are not, would the behavior of wood in an uncontrolled environment improve if the interior surfaces were coated as well? Are there coatings, or materials that could be incorporated in coatings, that would protect wood surfaces from light damage or from scuffing? Are there insect repellents that could be incorporated in coatings for the wood parts of upholstered furniture? These approaches may or may not yield usable results, but they and undoubtedly many other unorthodox ideas merit some investigation.
An entirely different tactic is the possibility of physical barriers. For example, the sides of furniture that face windows, such as the backs of upholstered chairs, could be draped with light-barrier cloth or ragboard invisible to the viewer. This approach, which has been tried in a few institutions, should be published where custodians of historic houses will read it. A conservator who treats collections for use in historic interiors needs to question not only the aesthetic goals of treatment but the ultimate location of the object and its environment: relative humidity, temperature, dust levels, gaseous pollution, insect incidence, access for handling, dust removal, and many more issues.