While restoring old frescoes and paintings has become routine work, "healing" more recent art objects made of plastics and other modern substances is more tricky. Germans are among the leaders in the field.
Checking for rust? Georg Uecker with one of his nail sculptures
The theft of Edvard Munch's world famous "Cry" from a museum in Oslo shocked the art world last August -- after all, estimated at €75 million ($98.5 million), it's one of the world's most valuable paintings.
But the natural decay of modern art causes much larger losses on an annual basis. The problem doesn't receive much public attention as the disintegration happens slowly and unspectacularly in museum vaults or private collections. Modern works crumble, get moldy or disintegrate as restorers try to keep them from falling apart.
Thoughtlessness, new materials and unusual ways to work with them make sculptures, paintings and installations appear old or cause them to decay even before their creators have suffered the same fate.
Saving ageing plastics
The Panton prototype chair is showing signs of decay
The ageing of plastics is one major factor that's threatening valuable art objects. The prototype of the famous 1967 Panton chair, the world's first plastic chair made in a single cast, for example, waits for salvation in the Vitra Design Museum in Weil am Rhein in southwestern Germany.
The chair's orange skin is breaking off. After examining the design icon, Friederike Waentig, a restorer from Cologne, has found the problem but is still looking for a way to deal with it. The chair is made of two different types of plastic which, in the long run, don't work together.
"There's a layer of pure polyester and another one that's a mixture of fiberglass and polyester," she said. "Every plastic reacts differently to warmth and humidity, resulting in tension. The fiberglass layer is much more active, there's more air inside, warmth and cold can enter and leave more easily. There's more leeway in that layer, causing the two materials to separate -- you can tell that's happening because there are small bubbles. That's our problem: How do you take out the tension and fill the holes?"
Along with her colleague, Kathrin Kessler, Waentig is currently running tests with 50 different types of glue.
Success via setbacks
What to do with Reiner Ruthenbeck's 1979 "White paper heap" once it turns yellow?
They shared their initial findings with hundreds of other restorers from Europe at a recent international conference on modern art restoration in Cologne. "Success via Setbacks" was the telling title of the event.
Germany is a leader in modern art restoration. Several universities offer course, and more than 200 members of the Association of Restorers specialize in modern art. These people are dealing with bigger problems than their "classical" colleagues. Refreshing old masters might be laborious, but it has become routine work; the way oil behaves on canvas is fairly well known by now.
Keith Haring, who died in 1990, also painted parts of the Berlin Wall
That's not the case with modern materials. One of the easier "patients" was Keith Haring's graffiti in an elevator at Utrecht's art academy, which had been partially destroyed by a cleaning lady who mistook it for vandalism. Art restorers used felt markers to fix the damage.
Felt itself has also been used by artists such as Joseph Beuys. The restorer of one of his artworks "caught" runaway felt-balls and re-implanted them when a Beuys objects started falling apart. Another method is to use gelatinous steam to salvage crumbling chalk drawings and glue broken plastic parts back together.
Respecting the artist
But salvaging the piece alone is not enough. "Spare parts" not only have to fit perfectly, they also have to be reversible in order to keep the work authentic.
That's why restorers are often confronted with ethical questions.
"You really have to work with the object," said Barbara Sommermeyer, who heads the modern art section within the Association of Restorers. "The most important thing is that the restorer always puts the art first. You have to respect the artist's ideas in order to find out what he or she wanted to get across with a specific object."
Restorer Klaus Leukas checks the "grafitti truck" in the Flick collection exhibition in Berlin after it has been vandalized by a visitor.
Some artists don't seem too concerned about what happens to their "children." They use all sorts of materials without thinking about what kind of chemical reactions they might provoke when combined. They mix plastics that decay when exposed to air. They screw together iron sculptures that already begin rusting in the studio. They create video installations that immediately start fading. They draw with fleeting chalk or body fluids, which might be considered distasteful by some but are highly appreciated by bacteria and fungi.
A lot of work
If the artists are still alive, restorers consult them before getting to work. But sometimes that's not very helpful.
Restoring Damien Hirst's 1994 "Away From the Flock" will probably be left up to a taxidermist.
"George Seagal is one example I like to mention -- he said we should just keep repainting his white sculptures," Sommermeyer said. "But at some point, that would mean that you're just left with a big white lump and that's not what you want, either."
It often takes restorers months to finish a project. But as the famous Bavarian comedian Karl Valentin pointed out almost a century ago, "Art is beautiful, but it's a lot of work."