Chemists And Curators Join Forces To Save Old Masters

Washington D.C., August 24 -- It's enough to make the "Mona Lisa" stop smiling. In an effort to preserve old paintings, collectors and curators unknowingly used untested and risky techniques that are causing the polymers forming their paints to fall apart, researchers reported today at the 220th annual meeting of the American Chemical Society, the world's largest scientific society.

Poor preservation techniques include trying to clean paintings with harsh chemicals, which soften and deform the paint. As these solvents evaporate and cause plasticizers to leach out, the paint becomes brittle, making it more susceptible to damage from extreme temperatures or frequent handling, they say.

"We are living with the consequences of improper preservation and we want to make sure this doesn't happen anymore," says Charles S. Tumosa, Ph.D., a chemist with the Smithsonian Center for Materials Research and Education, a part of the Smithsonian Institution, in Suitland, Md.

Paintings aren't the only museum holdings in danger of being lost to future generations. Reports on the deterioration of polymers used in everything from dolls to spacesuits will also be presented at the ACS meeting in a special daylong symposium on the preservation of polymers in museums.

Cracks, yellowing and warping are just some of the problems that plague centuries-old oil paintings. To determine how best to stave them off, Tumosa and his fellow preservationists, David Erhardt and Marion Mecklenburg, also Ph.D. scientists, use techniques ranging from recreating old paint to simulating the effects of temperature, humidity and time. Their sophisticated computer models can predict how actual paintings will fare. Armed with this knowledge, curators can act to prevent irreparable damage.

The paper on this research, POLY 452, will be presented at 2:35 p.m. on Thursday, Aug. 24, in the J.W. Marriott Hotel, Grand Salon I.

Charles S. Tumosa, Ph.D., is a senior research chemist at the Smithsonian Center for Materials Research and Education in Suitland, Md.

A nonprofit organization with a membership of 161,000 chemists and chemical engineers, the American Chemical Society publishes scientific journals and databases, convenes major research conferences, and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.