Oxygen Gives New Life to Art

The researchers at the National Aeronautics & Space Administration have their fingers in a lot of different scientific pots, but you'd hardly expect one of them to be art restoration. Yet that's exactly what scientists working at NASA's Glenn Research Center in Cleveland are doing.

Using an atomic oxygen treatment originally developed to mimic the upper reaches of the atmosphere, Bruce A. Banks and Sharon K. R. Miller have cleaned up damaged artwork that was once considered unsalvageable. They have also used the technique to restore an Andy Warhol painting that was literally kissed out of exhibition by an overenthusiastic art lover.

That project grew out of the space agency's Technology Transfer & Partnership Office, Miller explains. "We take technology developed for space and use it to benefit people here on Earth," she said during a session on art conservation at the Materials Research Society's meeting in Boston in late November. In the upper atmosphere, between 200 and 500 miles above Earth, intense ultraviolet radiation from the sun photolytically cleaves O₂ into atomic oxygen. Consequently, objects in low Earth orbit, such as communication satellites, the space shuttle fleet, and the International Space Station, need to be made from materials that can withstand these highly reactive oxygen radicals.

On Earth, Miller and Banks employ radio-frequency electric fields to generate atomic oxygen in a vacuum chamber. The researchers were using the chamber to test the durability of some satellite materials when they discovered that the treatment could remove organic materials from the surface of objects. This was bad news for some of the coatings that NASA was developing. However, after speaking with Bruce Christman, chief conservator at the Cleveland Museum of Art, they learned that the atomic oxygen technology might be able to restore smoke-damaged paintings, which can be resistant to traditional restoration methods.

To everyone's delight, the oxygen treatment worked spectacularly. The oxygen radicals converted the carbonaceous soot and char on the paintings' surfaces into volatile compounds such as carbon monoxide and carbon dioxide. The image of Mary Magdalen was recovered from one nearly blackened painting after 230 hours of atomic oxygen treatment. The colors were not altered, but the lengthy treatment removed much of the organic paint binder, and a replacement binder had to be added.

Because it is a gaseous treatment, the technique is appealing for art restoration efforts, Miller says. The gas contacts only the surface of the painting, so it can't damage underlying layers, and there's no mechanical contact with the artwork. Also, many paint pigments are metal oxides and therefore not affected by the process.

While their best results have been with oil and acrylic paints, Banks and Miller found that the oxygen treatment works with other media, too. They were able to clean up some smoke-damaged watercolors, ink drawings, and textiles, although in some cases they observed fading and slight color changes.

Miller cautions that treatment doesn't work well for everything. Pigments that are prone to oxidation will react with atomic oxygen. For example, the technique turns lead-based white paint a brownish color via oxidation. And ink from black Sanford Sharpie permanent markers could not be removed using the technique.

When it comes to treating priceless works of art, conservators are conservative by nature. Miller notes that atomic oxygen treatment isn't intended to replace commonly used techniques. Rather, she hopes that atomic oxygen will find use as an additional tool when these conventional methods don't work. "There's a historical comfort level with the conventional methods," she explains.

The Cleveland Museum of Art's Christman tells C&EN that he's been impressed with what the treatment can do, but he also says he can understand why conservators might be wary of it: "When you put a painting into a vacuum chamber and look at it from a little porthole knowing you can't get to it immediately, you just don't feel like you have the control that you want to have when you're cleaning a painting."

To treat artwork that had been defaced in a small area--by graffiti, for instance--Banks and Miller built a portable device, which delivers a pencil-sized beam of atomic oxygen to a specific area. This way, they can spot-treat artwork without putting the entire painting into a chamber.

THE RESEARCHERS got the chance to try the atomic oxygen beam on a famous work of art in 1998 when they were approached by conservators from the Carnegie Museums in Pittsburgh. The conservators hoped that Banks and Miller would be able to remove a lipstick mark on Andy Warhol's 1961 painting "Bathtub."

The offending peck was left during a cosmetic company party held at Carnegie's Andy Warhol Museum in 1997. Tubes of lipstick were given away at the event, and one attendee decided to plant a smooch on the painting.

"It never occurred to anyone that someone would try to kiss it," says Ellen Baxter, the Carnegie Museum of Art's chief conservator. "You have to kind of wonder what Andy would think about it."

Baxter, who was paintings conservator at the time, recalls that because the painting was unvarnished, she wasn't certain how to remove the stain. "Of all the paintings there for her to put her lips to, that was the worst one," she says. "This painting was so dry that it just sucked everything in."

All the ingredients that make lipstick luscious and adherent to lips also make it difficult to remove from an untreated canvas, Baxter explains. Water won't remove the cosmetic's oily compounds, and solvents would just drive the lipstick further into the canvas. Painting over it also was out of the question. "I couldn't use typical conservation methods to clean it," she says. "It was like trying to take a lipstick stain out of a piece of Kleenex." The painting was withdrawn from the exhibition until the mark could be removed--if it could be removed.

Enter NASA's atomic oxygen restoration system. After preliminary tests followed by a day of spot treatment with the portable atomic oxygen beam, the lipstick mark was gone. The treatment worked so well that it also cleaned up some dirt that had accumulated on the canvas, and Baxter had to lightly paint over the clean spot so that it blended with the rest of the painting.

Following the restoration, "Bathtub" was put back on display, and Baxter says she is delighted with the results. "I couldn't believe that you had to get NASA involved to do something about this," she says.