MORE than 50 years have passed since the restoration of a 16th-century painting in Naples turned into a nightmare dreaded by museum curators and art historians the world over. The original Madonna del Coniglio by Correggio was lost forever when the last layer of paint applied by the artist dissolved along with layers of unwanted grime in an overly zestful cleaning. In the 1960s the art world was again jolted when restorers realized only too late they had covered the 15th-century frescoes by Piero della Francesca in Arezzo with a protective varnish that whitened with age.
These are two particularly dramatic examples of botched restorations cited by a small but vocal group of Italian artists and art historians to illustrate the scenario they say is unfolding on the ceiling of the Sistine Chapel -- where Michelangelo singlehandedly painted 10,000 square feet of frescoes at the height of the Renaissance.
A team of highly respected and skilled specialists has been quietly at work since 1984 to reclaim Michelangelo's masterpiece from centuries of dirt and neglect. But criticism of the Vatican's colossal undertaking only flared up last February, when the public was given its first glimpse of a cleaned section of the vaulted ceiling. The unveiling came midway through the ambitious project -- a three-stage restoration of Michelangelo's works in the Sistine Chapel that began with the cleaning of the 14 half-dome lunettes above the windows and will end with the ``Last Judgment'' in 1992.
Part of the controversy over the restoration -- the subject of an earlier cover story in a major Italian weekly -- can be traced to many people's misgivings about a science that has proven to be so inaccurate in the past.
Alessandro Conti, a professor of art history who specializes in restoration at the University of Bologna, contends the Vatican restorers are making a mistake not unlike the Naples fiasco. ``My impression is that they are removing a series of glazings applied by Michelangelo that have endowed the frescoes with their special treatment of light and shadow and depth of field.''
Fabrizio Mancinelli, the director of the restoration, dismisses such comments as the product of a reflexive ``habit to blame current restorers for the errors of the past.'' Mancinelli, a specialist in Byzantine, medieval, and modern art who has worked at the Vatican museums for 15 years, says Vatican experts were ``certain as humanly possible'' before beginning the painstaking cleaning.
International experts were consulted; dozens of laboratory tests were performed; and historical documents were carefully perused before deciding on the best way to remove the thick accretion of dust, soot, and other substances Mancinelli says had kept the real Michelangelo from the public eye for so long. ``We are now probably seeing what people saw for the first 50 years after Michelangelo painted,'' says Mancinelli with evident pride.
All told, it will take a team of five restorers 12 years and $3 million to complete their task -- nearly three times as long as it took Michelangelo to finish painting the ceiling alone.
Funding for the project was secured by striking a deal with the Nippon Television Network of Japan. The Japanese network was offered exclusive rights of all photographs and footage of the restoration until 1995, three years after the scheduled completion of the cleaning of the ``Last Judg ment.'' A seven-member crew is on location at the chapel to record the minutiae of the restoration for posterity.
Mancinelli explains that the accumulation of dust and smoke from candles used to light and heat the room was so rapid that Michelangelo himself was dismayed to find his work soiled and in poor condition when he went to paint the ``Last Judgment'' 20 years later.
By the late 18th century, the condition of the frescoes had so deteriorated that the French astronomer Joseph-J'erome Le Francais De Lalande was nonplused by their beauty. ``The vault is not particularly impressive, the colors tend toward brick and gray,'' he wrote in 1768. Nineteen years later, Goethe, who in contrast was dazzled by Michelangelo's work during his stay in Rome, wrote glumly that he feared the smoke from incense and candles would eventually make the frescoes unrecognizable.
Efforts to restore the ceiling under various popes were piecemeal and sometimes did more harm than good. One method used, with limited results, was to mop up the dirt with chunks of bread moistened with wine.
What caused the most damage, however, and eventually led to the current cleaning was a gluelike substance that was spread over the frescoes, possibly as early as the 16th century, says Mancinelli. The coating, made of animal fat, was originally applied for a twofold purpose: to mask whitish water spots that had mottled the frescoes and to brighten the colors. Once the frescoes were thus covered, dust and soot were hopelessly trapped underneath.
The glue yellowed, hardened, and eventually cracked, becoming the nemesis of generations of restorers, says Mancinelli, adding that his predecessors at the Vatican were terrified of removing it for fear of damaging the Renaissance master's work. Mancinelli notes that the restoration was undertaken, with much trepidation, only when it could no longer be postponed. Vatican experts cleaning the 15th-century frescoes that line the lower walls of the Sistine Chapel noticed hairline cracks along the lower edge of the lunettes and decided to tackle the cleaning before the paint began peeling away.
It is the glue and not the paint laid by Michelangelo that is being dissolved by the laboratory-tested solvent used to clean the surface, Mancinelli assures.
But Toti Scialoja, an artist and the former director of the Academy of Fine Arts in Rome, says he is not swayed by the body of evidence presented by Vatican experts. Scialoja, who was among the first and most outspoken critics of the restoration when the cleaning of the lunettes was finished nearly two years ago, acknowledges his campaign has not picked up much steam. Few critics of international stature have endorsed his position.
Yet everyone agrees that a comparison before and after the cleaning is startling. Visitors to the chapel can now view two sections separated by the restorers suspended workshop -- a moveable bridge designed to fit in the same holes bored for Michelangelo's wooden scaffolding. On one side of the bridge, which conceals only one-sixth of the ceiling at a time, muted tones are transformed into a brilliant palette of metallic greens, sharp reds, and violets.
The intensity of the colors is already said to have prompted art historians -- who long maintained that Michelangelo's mastery of sculpture brought him to exalt form at the expense of color to rethink their views.
It is not, however, the newly discovered purity of color that Scialoja finds disconcerting. Michelangelo's work, he and others charge, has been sadly stripped of the subtle chiaroscuro that bathed his monumental figures in a mysterious light.
The cleaned frescoes, Scialoja argues, have been reduced to cartoons that are rife with ``unbalanced weights, contradictions, and vulgarities'' that could not possibly be the finished product of the same hand that created some of the world's greatest sculpture.
Questions about how extensively Michelangelo touched up his frescoes are at the crux of the debate. Did he paint almost strictly in pure fresco -- an extremely tricky process of applying color to damp plaster? Or did he go back once the fresco had set, using another medium, such as tempera or possibly a mixture of pigment and glue, to better blend colors, deepen shadows, or modulate shapes to his full satisfaction?
Leafing through a well-thumbed volume of quotations and notes in his office above the Vatican museums, Mancinelli stresses that Vatican scholars have culled all existing documents to reconstruct Michelangelo's technique. ``Our sources simply don't say that he touched up his frescoes,'' says Mancinelli, dismissively.
Yet not all evidence points in this direction. Art historian Conti of the University of Bologna says there is a dearth of information on Michelangelo's technique, and contends that what is available is often fragmentary and contradictory. Artist Mario Donizetti, who was commissioned by Time magazine to do a portrait of John Paul II, cites another 16th-century biographer and contemporary of Michelangelo's -- Condivi -- to disprove Mancinelli's premise that the Renaissance master only rarely touched up his work.
In a recent article published in a bimonthly science magazine, Donizetti contends the Vatican laboratory tests have no way of chemically distinguishing between a sootlike substance Michelangelo might have used in shading and the smoke from the candles that blackened the ceiling.
The paint and glue the Vatican experts are blithely rubbing away, Donizetti asserts, is the entire second hand applied by Michelangelo himself. If the project goes ahead as planned, Donizetti insists, ``it will be the cause of the biggest disaster'' in the already spotty history of restorations.