The Art Doctor.(Christian Scheidemann)

In late 2007, Ann Goldstein, the senior curator at the Museum of Contemporary Art in Los Angeles, asked Rosa de la Cruz, a collector of contemporary art who lives in Key Biscayne, Florida, if she would lend the museum a painting by Martin Kippenberger, for the German artist's first major North American retrospective. (The exhibition, which opened last September, travelled this spring to the Museum of Modern Art.) Kippenberger, who died in 1997, at the age of forty-four, was hard-living, prolific, and provocative: his varied oeuvre includes a sculpture of a coffee table, the surface of which is made from a canvas painted by Gerhard Richter, and a crucified wooden frog holding a stein of beer in one appendage and an egg in another. The painting owned by Cruz, titled "M.K.N.Y.," was completed in 1990 and is a self-portrait of sorts: the canvas bears a silk-screened image of Kippenberger, who is standing outside a bank in downtown New York with a missile in his arms, as if he were about to stage an assault upon the institution using techniques derived from Looney Tunes. Overlying the canvas, partially obscuring the image, is a thick sheet of latex, molded into crude patterns that suggest an enthusiastic adventure in finger painting.

Cruz was happy to let MOCA borrow the painting, which usually hangs in her modernist waterfront home. But, before shipping off the work, she took a close look at it, and discovered, as she put it later, that "the latex was moving a little bit." Cruz called Christian Scheidemann, a conservator of contemporary art who runs a company called Contemporary Conservation, and he asked her to send "M.K.N.Y." to his studio, in New York.

The painting arrived in less than reassuring condition. The latex, which had the color and translucency of amber, had become brittle and vulnerable to cracking, and was perilously saggy, in the manner of nylon stockings after excessive wear. After discussing the work with conservatorial colleagues and a former assistant in Kippenberger's studio, Scheidemann and his team settled upon a course of treatment. Having suspended the painting face down, they stabilized the latex by spraying it with a coat of archival-quality acrylic solution, both on its surface and on the inner portions that had loosened from the silk-screened canvas. Kippenberger did not like to frame his paintings, but Scheidemann recommended that the work henceforth be placed in a matte white frame, to prevent further damage. "Like a hospital bed," he said.

The Contemporary Conservation studio is on West Twenty-second Street, overlooking the West Side Highway. Like the best modern hospitals, the space is light and clean, and is occupied by calm, highly qualified personnel. Scheidemann, a genial native of Bonn, who moved to New York six years ago, presides over five conservators and administrators, most of whom are European and all of whom are female. They are a generation younger than Scheidemann, who is a youthful fifty-six. In the studio, there are four tables upon which works can be laid while they are being treated; the tables are surrounded by standing lamps that are typically used in hospitals as a palliative for depression. Conservation tools are arrayed in glass-fronted cabinets like the wares on an apothecary's shelves: a bottle of sealing wax called Cyclododecan, whose label reads "Do not eat, drink, or smoke"; half a pint of Heinz white vinegar; a tiny jar of International Klein Blue--the original, and very rare, pigment used by the minimalist artist Yves Klein, which Scheidemann was given by a colleague as a fortieth-birthday present.

Members of the art world invariably resort to medical metaphor when speaking of Scheidemann, who is tall, has tousled salt-and-pepper hair, and develops a quizzical furrow in his brow when he's concentrating or is immersed in conversation. "He's like a surgeon," David Leiber, the gallerist, says. Over several months, I saw various works that had been committed to Scheidemann's care. A Takashi Murakami "Louis Vuitton" painting had been dropped on its corner; Scheidemann was planning to rebuild the damaged section from the back of the canvas. An exquisite abstract painting by Rudolf Stingel, the silvery surface of which had been besmirched by fingerprints of unknown origin, needed to be resprayed with the original paint, in minute patches. (Luckily for careless employees of galleries and shipping companies, not to mention overly inquisitive visitors to collectors' homes, Scheidemann's work does not extend to forensics.) A canvas by the Cuban Surrealist painter Wifredo Lam had arrived in the studio infested with hundreds of tobacco beetles; it was propped up against a wall, vacuum-sealed in a pouch filled with argon gas, which, it was hoped, was killing off the pests. On one of my visits, Scheidemann showed me a painting that had been the unfortunate landing place for a soccer ball; the canvas had a rounded indentation, like the surface of a pond into which a pebble has just been tossed. To get it back into shape, he said, would take two months of carefully monitored flattening with iron weights. Another time, I saw a Paul McCarthy sculpture: a life-size mannequin wearing nothing but a green sweater, with an enormous red tomato instead of a head. The sculpture had been therapeutically decapitated by Scheidemann's team, so that one of them could work on repairing a patch of red paint on the rear of the tomato.

Though Scheidemann's iPhone will always ring after an accident--a Richard Phillips portrait of George W. Bush, dented by a fall; a minimalist painting accidentally sneezed upon at a museum--much of the work of his studio is preventive. He advises collectors on the correct temperature for a ...