University Chemist Applies Science to Field of Art Preservation

The art conservator counts time in centuries and a tiny loss of color over 100 years can stir deep concern. So when Keiko Keys saw pigments fade in only seven years, alarm bells sounded.

Keys, an art expert from Woodacre, Calif., near San Francisco, turned to the only man she knew who could do something about it: Robert Feller of Carnegie Mellon University.

Feller, a rumpled-looking chemist with an easy smile and the patience of someone whose most pressing deadline is usually hundreds of years hence, is one of the pioneers of the little-known science of art preservation.

‘Paid to Worry’

“The question is whether you should be preserving an old master as best you can,” Feller says. “And if something would fade 20% faster, let’s say, than it would otherwise, should you worry about it? I’m paid to worry about it.”

Keys’ discovery came on a return visit to the home of a private collector to study some Japanese prints by two beloved 18th-Century masters, Harunobu and Toyokuni. Some of the colors, she noticed, particularly the purples, had faded dramatically since her earlier tour. Keys, a consultant known for cataloguing and performing a technical examination of the Ainsworth collection of Japanese prints in the Allen Memorial Art Museum in Ohio, declined to give the name of the private collector.

Prompted by her concern that other prints might be suffering the same fate, Feller conducted a series of experiments. What he eventually found startled him.

The colors in many of the world’s great paintings may be fading much more quickly than thought--the result, ironically, of the care lavished on them by museums, he says.

Paintings ‘Made Comfortable’

The culprit is humidity, which most major museums keep at high, constant levels to prevent the cracking of canvases and wood. That’s important, Feller says, but it may be too much of a good thing.

“The public thinks the humidity is there to make them comfortable, but it’s really to make the paintings comfortable,” he says. “You walk into the National Gallery of Art, or any major museum with an air conditioning system, you’ll feel clammy.”

Feller, the director of the university’s Research Center on the Materials of the Artist and Conservator, arrived at a simple conclusion that had escaped the notice of conservators, most of whom are not trained chemists: A humid atmosphere is favorable to oxidation, which in turns promotes fading.

“You need moisture for most chemical reactions,” he says. “The moisture carries ions and gives it a good chemical ambiance to really jazz things up and get things going.”

Eyebrow-Raising Results

The 67-year-old Feller’s reputation among conservators is such that his results, though yet to be published, have already raised eyebrows in the staid museum community.

“To contradict something that Robert Feller comes up with is very difficult,” says Andrea Rothe, paintings conservator at the J. Paul Getty Museum in Malibu, Calif.

If Feller’s experiments prove convincing, Rothe says, “then we would have to do something about it. I would have to review my thinking.”

Although the modest Feller is happy to stay out of the public spotlight that often focuses on controversial art restoration projects--the most recent is Michelangelo’s Sistine Chapel ceiling--he is esteemed as a quiet champion of art.

‘Grand Old Man’

Bert van Zelst, director of the Conservation Analytical Laboratory at the Smithsonian Institution, calls Feller “one of the grand old men” in the still-new field of applying scientific techniques to the study of art preservation.

“He is kind of my hero,” Keys says. “There are a lot of younger scientists these days, but 15 years ago he was one of the only people doing work in this field.”

Feller’s reputation among art conservators blossomed in the 1960s and 1970s when his experiments revealed the fading effects of light in museums, many of them built with a modern architectural emphasis on open, sunlit rooms. One result was that the National Gallery of Art in Washington, D.C. put ultraviolet filters over its windows and others followed suit.

But the problem with testing the fading of most oil and water color paintings, Feller says, is that it’s “so darn slow you can’t see it in your lifetime. You can’t tell.”

Temperature, Humidity

The same is not true of delicate Japanese prints made with unusually “fugitive,” or unstable, vegetable dyes. In the 1980s, alerted by Keys and her husband, Roger, Feller found that he had a perfect medium for experimentation and turned his attention to the effects of temperature and humidity.

During World War II, museum conservators in England stowed paintings in mines and limestone caves to protect them from bombing raids, Feller says. When the war ended, they were surprised to find that old canvases suffered none of the blistering and cracking that had plagued them in the past.

The reason, they discovered, was a much more constant level of relative humidity--the degree to which the atmosphere is saturated with water--underground. Museums, then unregulated by air conditioning, experienced wide swings in humidity that caused canvases and wood to expand and contract.

Cracked Paintings

“About 85% of all old paintings are cracked,” Feller says. “We don’t know all the reasons for it but one of the obvious ones is that they’ve been expanding and contracting with humidity and temperature changes over the years.”

Since then, relative humidity has been kept at constant levels of about 50% to 55% in many of the nation’s major museums, among them the Metropolitan Museum of Art in New York City and the National Gallery of Art in Washington.

However, Feller and his colleagues at Carnegie Mellon, using a technique that accelerates aging, have found that 55% relative humidity may cause as much as 20% faster fading over a 10-year period than 35% relative humidity, particularly in unstable pigments like carmine red. Feller now recommends that museums move toward the lower level.

Some experts, however, disagree sharply with Feller’s proposal. Among them is John M. Brealey, chairman of the Department of Paintings Conservation at the Metropolitan Museum and one of the most influential art restorers in the world.

Low Humidity Stressed

“The notion that if you very slowly reduce humidity levels, that everything’s OK, this is complete nonsense,” Brealey says.

Brealey argues that even a gradual reduction would shrink wood paintings, causing paint to peel. In any case, he says, it would be virtually impossible for naturally humid places like London and Washington to steadily maintain such low humidity.

“There’s a constant flow of paintings on exhibition in America and from Europe,” he says. “If you tried to lower it in some places, it would have a monstrously adverse effect on works of art.”

Brealey says the efforts of Feller and others to protect paintings scientifically are sometimes useful, but their recommendations, such as to dim museum lights, are often carried too far.

“If you go too far with academics, then you forget your function: to delight the people who go to museums,” he says. “In the National Gallery of London, you practically need a torch to look at the paintings.”