Around the Mall & Beyond

Protecting museum treasures - paintings by the masters, the delicate wings of a tropical beetle - requires the strictest climate control, right?

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"We could save up to $400,000 on the electric bill for this building alone. Every year." That's what the man said.

I better get this right up top: I'm writing about some Smithsonian scientists who have shown that museums and galleries are spending far too much money on climate control. Photographs, old planes, bones, rare bugs and what have you are much tougher than we thought.

That's the short version. It was not easy to come by. I had no trouble finding the Conservation Analytical Laboratory Research Group at the Smithsonian's sprawling Museum Support Center at Suitland, Maryland, but the scientists themselves were another story. They spoke a language of numbers, acronyms, graphs and formulas that made me yearn for the simplicity of E=mc2. Slowly I began to make out what they were telling me.

"Until a few years ago, people didn't know precisely how much objects are affected by fluctuations in relative humidity and temperature," explained Charles Tumosa, "but they knew that existing air-conditioning systems could maintain humidity at 50 percent, plus or minus 5 percent. So they felt that was what it should be, and if plus or minus 5 percent was good, plus or minus 2 percent was better." Believing only that too much fluctuation in the atmosphere was bad, museums and galleries concentrated on reducing that tiny plus-or-minus factor.

"As sensor and HVAC (heating, ventilation and air-conditioning) systems got better, they tightened and tightened their specifications, going for that utopian 0 percent. To do anything less would be morally reprehensible. They could spare no expense."

Museum professionals had observed that huge changes in air conditions cause damage; but it wasn't known if small changes over a long period do, too. In the 1970s, administrators at the National Gallery of Art in London, going by certain experiments on wood and recalling their wartime experience when paintings were stored in a cave without damage, set a conservative (if not entirely arbitrary) standard of 55 percent relative humidity for the building.

This standard was designed to accommodate all sorts of substances, with major exceptions such as metal, which corrodes, papers containing acids, and cellulose acetate film base, which breaks down. In other words, at that time museums knew that extreme conditions damage materials, but they did not know how much, or when. So they overcompensated.

This is where the Smithsonian's lab came in. Marion Mecklenburg, for 20 years an art conservator, got a doctorate in engineering just so he could explore this field. He has put together a remarkable team to try to determine exactly how the environment does affect objects. Mark McCormick-Goodhart, a renowned photographic scientist, holds many patents from his years in industry; PhD chemist David Erhardt comes out of an advanced math background, as do Mecklenburg and Tumosa, a PhD chemist who did forensics for 18 years with the Philadelphia police before coming to the Smithsonian.

"Let's look at the physical and mechanical problem of relative humidity and temperature fluctuations," said Mecklenburg in his brisk way. "No serious work had been done on this. We were the first."

Different materials, different problems. Oil paints, acrylics and other painting media can be damaged by extreme cold, Mecklenburg explained, but they are not especially vulnerable to moisture.


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