And the Jonah figure, which serves as a focal point of the entire work, is dramatically diminished by the lack of shadow and definition. Many figures in the painting now have a sort of washed out, rough appearance.

How could this have happened, no less to one of the most significant cultural works of the Western canon? Beck attributed it to the restorers' arrogance, that their confidence in knowing the artist's intentions and method led to the painting's ruin. The restorers began their work in relative isolation without consulting an outside, independent committee of art historians, artists or scientists. Beck pushed for this committee in 1987, when the ceiling was already half completed; one did convene later that same year, however, and filed a complimentary report.

"The new freshness of the colors and clarity of the forms on the Sistine ceiling are totally in keeping with 16th-Century Italian painting and affirm the full majesty and splendor of Michelangelo's creation," the report refuted.

Thus, critics were not able to halt what they saw as destruction of Michelangelo's work. But they were able provoke a response. To date, ArtWatch has still not been widely successful in preventing these sorts of restorations. But ArtWatch has seen success in changing the conversation surrounding restoration, from one that is overly laudatory to one that is initially suspicious.

It was difficult for interested parties to track the ongoing work -- the result of the restoration's sponsorship by Nippon Television Network Corporation. The network paid $4.2 million dollars to the project in exchange for exclusive rights to document and photograph the restoration. It seems, on its face, like a conflict of interest, to entrust the proper documentation of the restoration to a company that stood to benefit the most from a positive portrayal. A positive review of the restoration by The New York Times in 1990 noted that Nippon had made the restoration photos prohibitively expensive and had not yet provided the requisite before-and-after photographs that would address critics' concerns.

Thus, ArtWatch's dual, primary concerns are an overzealous approach to restoration using new techniques, which risks damages that cannot be reverted, and the influence of corporate money, which calls the ethics and motives of the restoration into question.

In 1978, Pinin Brambilla Barcilon began work on what was, once again, promoted as the final, authoritative restoration of The Last Supper. This time, rather than attempting to retain the work of prior restoration attempts, her goal was to strip it all away -- the shellac from the prior restoration included -- and get down to da Vinci's handiwork alone.

Only approximately 20 percent of the original painting had survived.

Barcilon viewed the painting through a microscope and then slowly, gently blotted the painting with solvent, using small bits of Japanese mulberry cloth.

The end result was a sad revelation: Only approximately 20 percent of the original painting had survived. There was, however, a trade-off: Barcilon uncovered many details, buried underneath the prior restorations, that were once thought lost. An orange here. A hand's definition there. A face with different dimensions and expression.

The missing parts of the painting, meanwhile, were filled in with beige, to give an indication of what the painting once looked like. In Barcilon's own words, from her book Leonardo: The Last Supper, which documented her entire process:

"Where the pictorial film was missing, the initial procedure was to reintegrate the image based on neutral tonal reduction (neutro), intended to create an ideal background of homogeneous color for the original fragments. In the interest of achieving greater legibility and unity, a method of reintegration that approximated the surrounding color was adopted later. Executed in watercolor, the reintegration was particularly laborious and delicate because the surface absorbed the color unevenly, requiring repeated applications and a gradual buildup of tonal intensity."

The book explains and rationalizes the before and after for every part of the painting; it is exhaustive in its attention to detail. To illustrate, here is an excerpt of the before state of Thaddeus (the middle apostle in the above photograph):

"Before the latest restoration, the figure generally appeared dark, and the facial features were undefined. A dark diagonal stroke roughly designated the eyes. The hair blended in with the gray field of the wall behind the figure, and the almost indistinct volume of the hair was flattened in an abbreviated mass."

And here is an excerpt of the after state of Thaddeus:

"Numerous and unexpected recoveries of original material emerged from beneath the blanket of repaint, especially in the face and the hair. The hair reacquired its initial volume, modulated by wavy locks threaded with subtle highlights and delicate white brushstrokes, while a soft gray glaze skillfully emphasized the hairline. The facial features proved leaner and purer, even on a chromatic level."

Clearly, this restoration was a labor of love and devotion; one could hardly spend 20 years nose to nose with something without it being so. Critics, however, took issue with several points of this restoration, the first being its necessity. If so little of da Vinci's original work remained, reasoned critics, then why strip away the record of prior restorations, which had become a part of the painting's history? What was the sense of having something that was more Barcilon's watercolors than da Vinci? Shouldn't the more historically noteworthy restorations have remained instead?

"Restorers have a professional imperative, rather than to reflect upon what they're seeing, to do something about it," said Daley.

One might speculate that the corporate sponsorship, this time of tech manufacturer Olivetti, may have also increased pressure to act -- to be proactive for the amount of money that was being spent rather than do nothing at all.

Science captured the imagination of Western civilization in the wake of World War II, which was won, in part, due to the superior technology of the Allies. "In the second half of the 20th century, restorers, who themselves were technically and scientifically naive, became enthralled and envious of the authority of scientific people and disciplines." said Daley. "Science is used to make their activities more respectable than they might be. Restorers try to maintain the scientific aura of impregnability."

Science, in other words, can be used as a cudgel and conversation-ender to give cover to untested techniques that may not, in actuality, be all that scientific. And because there are still ongoing, internal debates over major aspects of restoration -- such as whether solvents or soaps are even safe to use -- one might conclude that a restoration is often not worth the risk. A risk, Daley claims, was taken with The Last Supper.

"The restorers painted the bare wall in these watercolors, and it's made the painting into a kind of modern decoration," lamented Daley.

ArtWatch is not alone in its criticisms.

"[The restorers] decided to proceed without even conducting the proper analyses to determine how much of the original painting remained," said Mirella Simonetti, a Bologna-based restorer, in a 1995 interview with The New York Times. "And now they show these remaining crumbs, these plates and glasses, and say it is Leonardo."

In a final cruel irony, Tom Hundley, who wrote about the restoration for the Chicago Tribune in 1999, made the following cautionary point: The painting, no longer protected by the shellac or any overpainting, was now more vulnerable to the elements and environment than ever before.