"We have a project now with an artist who mixes chewing gum and rubs it into the canvas," Christian Scheidemann said in his light German accent. "Looks very nice."

The Art Doctor's nickname seems appropriate. Tall and slim with a Roman nose and sleek brown eyeglasses, Scheidemann quietly orders a macchiato with sugar at the Blanton's Cafe.

Scheidemann is in town as a guest lecturer hosted by the Blanton Museum of Art to explain his area of expertise: the restoration and creation of the world's most challenging artworks. From sharks in formaldehyde to food and elephant dung, his New York laboratory sees the world's most challenging materials and artistic ideas.

Trained as a traditional art conservator, Scheidemann was based in Germany, advising on the condition of paintings and the like, when Robert Gober, the post-modern sculptor, brought him a bag of doughnuts.

"They were real, and he coated them with roplex, an artificial resin, and then one of the critics, he didn't like the show, apparently, and he took a bite of a doughnut, and then he found himself in the hospital, his stomach had to be pumped out." Scheidemann grinned. "He thought this was very funny, but it was not very funny ... he didn't understand the work."

Scheidemann took on the project, creating a process that sucked out the fat in the doughnut and replaced it with resin, making them invulnerable to attack. And snack attacks.

His firm began to specialize in unique materials, developing techniques as they went. They moved to Manhattan to consult with artists in situ.

Scheidemann is fond of the "Art Doctor" metaphor. He likes the idea of being surrounded by artwork that needs help; working to find a solution, doing tests and being deeply entrenched in work.

"I think the reason I became a conservator is because I like to see both sides of the work. You can always see the back side and all the labels and fingerprints of the artist, all the tests and the doodles."

A conservator's work is entirely hidden. This, too, has its appeal, Scheidemann said. "What I like about our profession is that we do not create anything, we do not make anything, we do not produce anything, which is nice."

"There's so much around here," he says, looking around the café. "People make design, make chairs. Our work is very invisible somehow."

Nor is Scheidemann is trying to preserve work indefinitely. "If the artist says, 'It's supposed to decay within three years,' then we say, 'That's very interesting, that's fine, if that's what your art is about.'u2009"

"At one point a work has to go out in the world and you cannot always remake them, because then you avoid history," he said.

That doesn't quite stop him from trying to make unusual objects cheat an untimely end. "We have a banana in our studio that is 12 years old now." Would you eat it? I ask him. "You could, actually, dip it in water and then eat it. It's preserved because all the moisture has been removed.

"The challenges of contemporary art are so huge because of the new materials, like Vaseline and chocolate, lint and soap and toothpaste. Artists work with everything nowadays," he said. "In previous times you would have painted a lemon or painted a still life. Today, you put the lemon on the table and expect it to last two hundred years."

"It's not possible," Scheidemann continues. "Or actually, it is now possible," he laughs.