A recent article in the American Association of Museum’s magazine Museum discussed the somewhat thorny issue of conservation standards in the environmental conditions for modern museums. Titled “Crack Warp Shrink Flake: A New Look at Conservation Standards,” the article covers the problems and damage that can occur when humidity and temperature levels are not kept at certain levels within museums. Now a casual reader to our blog might ask oneself why these standards are under question. Most visitors to museums, and especially to the collection storage areas of those facilities, will notice how the temperature at most facilities resides somewhere around 70 degrees Fahrenheit (+ 2), while the humidity stays at around 50% (+ 5), relative humidity. These figures, 50/70, are the general levels most museums strive for within their facilities. The article in Museum goes into the history of how these figures were devised as well as if these figures are in fact relevant.
As to how the figures of 50/70 were devised Pamela Hatchfield, the author of the article, traces that bit of history back to the turn of the last century and the evolution of modern day indoor environmental controls. Beginning with the textile industry, and eventually adopted by the Museum of Fine Arts of Boston in 1905, the museum industry stipulated that all facilities should be able to establish parameters of 50 to 60 degrees Fahrenheit in order to keep the relative humidity at least as high as 50%. Just 20 years later, most museums in the U.S. were attempting to operate at 55 degrees Fahrenheit. These levels were further shown as being beneficial to museum collections during World War II when the collection of the National Gallery in London were kept in a stone quarry whose levels remained at 58 % relative humidity and 63 degree Fahrenheit. The objects kept in this location where noted as having little to no flaking and cracking, while when the objects were returned to the uncontrolled galleries in London, damage was immediately observed.
By the late 1970s the levels of 70 degrees Fahrenheit (+ 2) and 50% (+ 5) relative humidity were held to rigid specifications in the museum field, with no compromise being given to environmental conditions outside the facilities or types of objects within the collection. These levels, as noted earlier, are good general rules of thumb for general museum collections. But it is well known among most museum professionals that certain types of objects within the collections, specifically negatives and photographs, can be kept at much lower relative humidity levels. Also items that are used to a dry environment, such as a desert, would not handle an immediate introduction to the much more humid level of 50% relative humidity.
So with these issues, along with others in mind, conservation experts have been asked to reassess the levels of 50/70 to ensure they are the best for the objects we have been entrusted to look after. Culminating with a report issued by the American Institution of Conservation in June 2010, the most recent interim standards have established that most cultural institutions should strive for a set point in the range of 45-55% relative humidity (+ 5), with a total annual range of 40% minimum to 60% maximum and a temperature range of 59-77 degrees Fahrenheit. These levels, as one can see, are much more relaxed and try to take into account the ranges most of us see within our facilities. Another main point stressed in the report is that at all major fluctuations in temperature and relative humidity must be minimized, as this is event that causes the most stress to the objects themselves. The report also acknowledges that some cultural materials require different conditions to ensure their preservation and that loan requirements between institutions should be determined in consultation with conservation professionals.
Ultimately these guidelines, which are considered interim and could ultimately change, have acknowledged the fact that most institutions have collections that contain and wide variety of objects. Because of this environmental conditions must be tailored to reflect both the material types and the environment they reside in, in order to ensure that they will be preserved for the future.
For further information concerning this topic, and other select articles from the American Association of Museum’s magazine Museum, please refer to the following link: http://www.aam-us.org/pubs/mn.cfm.