CLEVELAND, Ohio -- Paintings conservator Dean Yoder made his debut Tuesday as the co-star in an unusual new exhibition at the Cleveland Museum of Art.

For the next 14 weeks, he'll be working in the museum's highly visible Focus Gallery on the conservation of the museum's 1607 painting by Michelangelo Merisi da Caravaggio, "The Crucifixion of Saint Andrew."

Cracks in the surface of the Cleveland Museum of Art's Caravaggio make the image hard to read.

Visitors will be able to watch as Yoder uses cotton swabs and a specially concocted solution to clean the painting, millimeter by millimeter.

Among other things, the project will help determine whether the work is able to travel to Sicily next year as part of a promised cultural exchange.

Conservation at the museum usually takes place out of sight in a behind-the-scenes laboratory on the institution's lower level.

Yoder, however, will be at his easel in the Focus Gallery during working hours, just off the museum's central atrium, where he'll take breaks and answer questions.

A native of Cleveland Heights, Yoder ran his own conservation business in Cleveland for 24 years before joining the museum's staff in 2009. He said he's traveled to Paris and Vienna to inspect other Caravaggios, and is planning a trip to Rome to continue his research while working on the Cleveland painting.

The public cleaning of the Caravaggio will echo efforts in European museums and churches, where conservation on works too large to move takes place in public out of necessity.

"It's going to take some time, and I'll have to go slowly," Yoder, 55, said Tuesday. "The ultimate goal for me is to make this painting find its full potential, aesthetically."

Considered one of the most important works in the museum's permanent collection, the Caravaggio, acquired in 1976 from a collection in Spain, is one of a handful of paintings by the artist in American museums.

The gaunt woman in the Cleveland Museum of Art's Caravaggio exemplifies the artist's realism.

An artist with a hot temper, Caravaggio spent the last four years of his life on the lam while seeking a papal pardon for killing a man in Rome during a knife fight. He died in 1610 at age 38.

Despite his propensity to brawl, Caravaggio was hugely influential. He left scores of "Caravaggisti" followers and had a huge indirect impact on Rembrandt.

Caravaggio's big innovations included his gritty sense of realism and his dramatic use of raking light, which conveyed a sense of the miraculous amid the squalor of everyday life.

The "Saint Andrew" portrays the miracle in which Roman soldiers in a Greek colony are unable to untie the knots binding the crucified saint, who has prayed to die on the cross in emulation of Christ.

Witnesses to the miracle include a poor woman with a goiter, shown praying at the feet of the dying saint.

Yoder's work on the canvas will last approximately 16 months and will be completed in the museum's lab after the end of "Conservation in Focus," as the project is called.

By then, the museum hopes to resolve whether the painting can travel, as promised, to Sicily for an exhibition of Cleveland treasures.

In one of his last acts as director of the museum before he resigned last October, David Franklin agreed to lend the Caravaggio and other works in exchange for an exhibition of Sicilian antiquities.

A detail of a large infrared image of the Cleveland Museum of Art's Caravaggio shows repaired rips in the canvas that cannot be seen with the naked eye.

Cultural authorities from the island region had previously agreed to send the exhibition to Cleveland after its run at the J. Paul Getty Museum in Los Angeles. The two institutions co-organized the show.

Nevertheless, after an election and a change of government in Sicily, a new group of authorities threatened to cancel the show's run in Cleveland unless the museum paid hundreds of thousands of dollars in loan fees imposed at the last minute.

The Sicilians withdrew the demand after Franklin offered to lend the Caravaggio, which he called "a bargaining chip," along with other works.

Franklin and the Cleveland museum earned praise for not knuckling under to the financial demand, which could have set a dangerous precedent for other museums. At the same time, the arrangement raised questions about whether the painting is too delicate to make the trip to Sicily.

The Cleveland museum now says the deal has not been finalized. Its leaders say that Sicily has not yet responded to requests for information about climate control and security in venues where the Cleveland artworks would be shown.

They're also saying the Caravaggio won't travel unless Yoder's work shows it would be safe for the painting. For now, the work remains on a "do not travel" list.

"It wasn't put on the list because of Sicily, but because of its fragility," said August Napoli Jr., the museum's deputy director and head of institutional advancement. "It would be on the list until we can be sure it's strong enough to travel."

As of Wednesday morning U.S. time, Sicilian authorities had not responded to an email query sent Tuesday night.

As is obvious from a close inspection of the painting on Tuesday with Yoder, the Caravaggio faces numerous complex issues.

Among them is a problematic sealant on the surface of the painting that a previous conservator described as a "natural resin," according to Yoder. Yoder said the material actually turns out to be shellac.

The coating has discolored to a brownish-yellow, and may be contributing through shrinkage and expansion to a series of pronounced cracks across the painting.

Highlighted areas in the Cleveland Museum of Art's Caravaggio that were painted with lead white are more stable and less cracked than areas in which the artist used dark pigments.

Those cracks, in turn, have become a major distraction. They act like tiny, V-shaped canyons that dig through layers of paint, extending as deep as the fibers in Caravaggio's canvas.

"The varnish layer is brittle and the cracks are deep," Yoder said. "The lighting hits the edges of the fractures; it's distracting. The cracks kill the depth of the painting. You can't see into the picture."

If the painting traveled in its present condition, changes in temperature and humidity could cause additional stress to the painting's surface and worsen the cracking.

Leaving the painting alone is not an option, because the aging varnish is "definitely stressing the surface" now, Yoder said. "We need to do something with the painting."

The display in the Focus Gallery includes a full-size infrared photo of the painting, along with a full size X-ray.

Those images show numerous rips, tears and patches that are invisible to the naked eye, along with passages Caravaggio reworked. For example, he lowered the hands of the woman with the goiter, perhaps to reveal the unsightly bulge on her throat with greater clarity.

The temporary lab in the Focus Gallery includes a fume hood with a fan to whisk away chemical vapors. Lubrizol donated $50,000 to provide a remote-controlled microscope mounted on a heavy steel table, which Yoder will use to make a highly-detailed map of the painting's surface.

Precision fittings on the table that are used to position the microscope were made by Parker Hannifin.

Yoder said he first plans to clean dirt off the surface of the Caravaggio with swabs, although he declined to say what kind of solution he'd use, because he wouldn't want do-it-yourselfers trying the technique at home.

Repairs and "in-painting," which involves filling areas of lost paint, will follow, along with a new coat of protective varnish.

An X-Ray shows a rip through the eye of the Roman soldier in the Cleveland Museum of Art's Caravaggio - a damaged area covered up by subsequent repairs.

Yoder said he believes he'll be able to reveal Caravaggio's original color scheme for the painting, long obscured by the discolored varnish.

A test cleaning of a small area on armor worn by the Roman soldier in the foreground of the painting, for example, shows an area of grayish violet – not the soupy brown it now appears to be in the adjacent unclean sections.

"The ultimate goal for me is to make this painting find its full potential, aesthetically," Yoder said.

As to whether the painting will travel, he'll make a recommendation when his work is done, but the decision will be made by the museum, he said.

When asked how he felt about carrying the delicate cleaning of the painting in public over the next few months, he said: "There is a certain performance aspect to this, but the main thing is that it's going to be very rewarding to work on such a great masterpiece."