The Art Newspaper

Revising the gold standard of environmental control

There is an impasse preventing the world’s art museums from adopting less stringent standards

By Maxwell Anderson. Comment, Issue 212, April 2010
Published online: 08 April 2010

It remains an unshakable conviction for most conservators and administrators that unless a museum can guarantee lenders that its interior climate is 70 degrees Fahrenheit (21 degrees celsius) and 50 per cent relative humidity (with an allowance for minor fluctuations), it has no business asking for loans, and cannot be trusted with its own collection. That conviction informs many facets of a museum’s operations beyond the cost, including how art is borrowed, lent, shipped, installed and stored.

There are three considerations involved in prescribing the upper and lower limits of relative humidity, or RH. The first is the RH set point—the most generally accepted percentage of relative humidity. The second is the allowable fluctuation—the extent to which higher or lower percentages are considered acceptable. And the third is the seasonal adjustment—the extent to which the set point is permitted to change based on the impact of higher and lower exterior temperature and humidity.

The identification of fixed set points was explored in the early 20th century in select US museums, but the defining events surrounded emergency responses to the aerial bombardment of the UK in the first and second world wars. Temporary storage of the British Museum’s collections during the first world war in underground rail tunnels was followed by 1930s studies of the effects of humidity on art, but with mixed evidence about the specific effects of different ranges. With the advent of the second world war, works from several galleries and museums were stored in environmentally stable slate quarry caves in Wales, with no discernable changes in their condition. In the aftermath of the war, the approximate temperature/humidity ratios of the caves became the gold standard for climate control in museums.

By 1960, scientific inquiry had bolstered the legitimacy of these set points, as articulated in studies such as H.J. Plenderleith and P. Philippot’s “Climatology and Conservation in Museums” of 1960. Like others preceding it in Britain, this particular study concluded that changing relative humidity was a key culprit for the degradation of works of art, but did not advance our knowledge of specific ranges that were better or worse for specific media under specific circumstances.

These earlier assumptions were challenged 16 years ago. In 1994, the Smithsonian Institution’s Conservation Analytical Laboratory issued revised guidelines allowing for as much as 15 per cent fluctuation in relative humidity (35 per cent to 65 per cent) and fluctuations by as much as ten degrees Celsius (52 degrees Fahrenheit to 88 degrees Fahrenheit), regardless of the materials from which objects were made. As research progressed others also came to the conclusion “most museum objects can tolerate, without mechanical damage, larger fluctuations than previously thought” (David Erhardt and Marion Mecklenburg, “Relative Humidity Reconsidered” in Preventive Conservation: Practice, Theory and Research, 1994).

No one would argue that environmental fluctuations should be allowed to occur unchecked within a museum. But the question is this: given the scientific evidence that works of art made from multiple categories of media have not been shown to sustain damage from the incremental fluctuation of relative humidity to a greater extent than currently prescribed, is it time to arrive at an international consensus on loosening environmental strictures?

Some of today’s protagonists moving this discussion towards new protocols include Nicholas Serota, the director of the Tate, along with members of the scientific community, including the International Institute for Conservation (IIC). In May 2010, the IIC and the American Institute for Conservation will be co-sponsoring a roundtable session in its series “Dialogues for a New Century” to review the latest findings, and address the impasse still preventing the world’s art museums from adopting a less stringent standard (the discussion follows a September 2008 summit in London, “Climate Change and Museum Collections”). Many of us hope that a new protocol tolerating greater elasticity may be the outcome, allowing for significant cost savings in energy bills, a reduced impact on carbon emissions, and a more reasonable approach to sharing art treasures with institutions that have heretofore been penalised for failing to meet the rigid standards that have prevailed since the second world war.

The writer is the director and chief executive of the Indianapolis Museum of Art