The sweat of millions of tourists forced the Vatican to take on the "Last Judgment" for the first time in 32 years.

On January 12, 2026, scaffolding was erected near the altar wall of the Sistine Chapel, where Michelangelo’s fresco "The Last Judgment" is located. The unscheduled intervention was prompted by an unusual enemy: visitors’ sweat, which had settled on the surface of the painting year after year, turning it into a whitish salt crust.

This is the first time restorers have been working since a major campaign in 1994. Back then, the "Last Judgment" was cleaned after decades of contamination, revealing the fresco to the public in colors few could have imagined. Three decades have passed, and the monument is once again in need of help, this time due to record tourist influx and climate change.

White curtain over the painting

A disturbing film on the altar wall was first noticed in 2025. Barbara Jatta, director of the Vatican Museums, compared the resulting film to a cataract — it blurs contrasts and dulls colors that had been literally rediscovered thirty years earlier. According to her, several trial cleanings were performed, "and immediately there was a much better result," confirming the need for a full-scale intervention.

The plaque was distributed unevenly: the densest layer accumulated closer to the ceiling, where warm air from the crowd of visitors rises. The altar wall proved more vulnerable than other surfaces. Fabrizio Bifarali, curator of the 15th-16th-century art department, explained the reason: this wall is colder than the others, so moisture from exhaled air and skin evaporation condenses more readily on it.

The Chemistry of Sweat and Lime Plaster

Fabio Moresi, head of the Vatican Museums’ Office of Scientific Research, explained the mechanism of deterioration at a press screening on February 28, 2026. When a person sweats, the skin produces lactic acid. In the Sistine Chapel, this acid reacts with calcium carbonate — the base of the lime plaster on the wall — to form calcium lactate, a white salt. It doesn’t dissolve, but settles directly onto the painted surface.

The process itself is slow: a single visitor leaves behind a negligible amount of material. But about 25,000 people pass through the Sistine Chapel daily, and around six to seven million annually. In the thirty years since the last restoration, the accumulated layer has become dense enough to dampen the chiaroscuro — the sharp contrasts of light and shadow that form the basis of this fresco’s expressiveness.

Global warming has accelerated this process. Italy has become noticeably warmer in recent years, tourists are sweating more profusely, and the humidity inside the chapel is rising — even despite the functioning climate control system. Moresi directly cited climate change as one of the factors explaining why the salt has accumulated so rapidly now.

What is a fresco and why is it vulnerable?

Fresco is a painting technique on wet lime plaster, known as buon fresco. Pigments are applied to the damp surface and, while the plaster is setting, chemically bond with calcium carbonate crystals. This bond is strong: this is how fresco paintings last for centuries.

However, this same calcium base makes plaster vulnerable to lactic acid. The calcium lactate formed during the reaction doesn’t immediately destroy the pigment, but rather deposits on the surface as an opaque white film. Over time, this film builds up, and the dark, rich shadows — especially noticeable in Michelangelo’s work — gradually lighten, losing depth.

The History of the Creation of the Last Judgment

" The Last Judgment " covers the entire altar wall of the Sistine Chapel — an area of approximately 180 square meters, measuring approximately 13.7 by 12.2 meters. The fresco depicts the Second Coming of Christ: a powerful figure rises from the center, right hand raised, judging humanity. The righteous ascend from the left, while the condemned descend to the right, toward Charon and Minos — the lords of the underworld, inspired by Dante’s Divine Comedy.

In 1533, Pope Clement VII commissioned the painting of the altar wall, shortly before his death the following year. His successor, Paul III Farnese, not only confirmed the commission but also specifically released Michelangelo from his duties on the tomb of Julius II, granting him the title of "Supreme Architect, Sculptor, and Painter" of the Apostolic Palace. Work began in the summer of 1536 — approximately twenty-five years after the completion of the vault of the same chapel — and was completed in the autumn of 1541. Michelangelo was then about sixty-seven years old.

Nude scandal

The fresco depicts 391 figures — almost all of them nude when painted. This sparked a wave of outrage even during Michelangelo’s lifetime. Papal Master of Ceremonies Biagio da Cesena complained to Paul III about the inappropriate "nudity" in a sacred space. In response, Michelangelo, according to legend, painted Biagio’s face as Minos — the judge of the underworld — with donkey ears. When Biagio complained to the pope, Paul III replied that his authority did not extend to the underworld.

After Michelangelo’s death in 1564, the Council of Trent decreed that the nude figures be covered. The artist Daniele da Volterra — nicknamed "il Braghettone" ("the trousers maker") for this — added drapery to dozens of the figures. Some of these additions were removed during the 1994 restoration, while others were retained as part of the monument’s historical alterations.

On October 31, 1541, Paul III celebrated Vespers before the newly completed fresco. As Giorgio Vasari later wrote, the work "filled all of Rome with awe and admiration" — a painting before which "the senses become speechless."

The 1994 restoration and its aftermath

The Last Judgment was restored between 1980 and 1994, along with the rest of the Sistine Chapel frescoes. The project was overseen by museum director Carlo Pietrangeli, and the work was carried out directly by chief restorer Gianluigi Colalucci. It was one of the most discussed conservation projects of the 20th century.

Beneath centuries of soot and candle smoke, colors of a completely different nature were revealed: rich blue tones of the sky, vibrant flesh tones of hundreds of figures, sharp contrasts of light and shadow. Michelangelo’s image as a painter of dark, muted colors demanded a rethink. The public and experts alike saw a fresco fundamentally different from the one they knew from reproductions.

However, the restoration also sparked a scholarly debate that continues to this day. Some researchers claimed that the original secco paintings — finishing layers applied by Michelangelo to the already-dried plaster — were removed along with the stains. Opponents insisted there were no traces of such a technique. This controversy reminds us that every touch on a masterpiece is simultaneously an interpretation, not just a cleaning.

Current Operation: Japanese Paper vs. Salt

The current intervention is fundamentally different in both goals and methods from the 1994 work. Back then, centuries of contamination had to be removed using chemical and mechanical tools. The current task is more modest in scope but no less delicate: removing the thin salt crust without disturbing the underlying paint layer.

Restorers use Japanese washi paper. The sheets are soaked in distilled water and placed on the fresco’s surface. The water moistens the calcium lactate, softening it and adhering to the paper fibers, and the sheet is removed along with the contaminants. Paolo Violini, director of the Painting and Wood Materials Restoration Laboratory, described the technique as straightforward but requiring high precision: the paper’s moisture content, pressure, and contact time must be precisely calibrated, otherwise the risk of damaging the painting increases dramatically.

The restoration team numbers between ten and twelve people. They are working from scaffolding set up against the altar wall. Already in the first weeks of cleaning, the effect was noticeable: hair and nail marks on the wrists of the central figure of Christ, previously barely visible under the salt film, became clearly visible.

Discoveries in the process

Bifarali told the press that the cleaning also yielded scientific results: the cleared areas reveal technical details of the artist’s style that were previously inaccessible to study. Vatican experts are not yet releasing details, noting only that they are revealing features of the painting technique previously hidden from view.

A similar effect accompanied the 1994 restoration: unexpected technical details were revealed beneath the patina. New information emerged about how Michelangelo worked with pigment and constructed volume through color rather than contour. The current cleaning is practically taking place live — the Vatican opened the scaffolding to the press in late February 2026.

The chapel is open and the wall is behind a screen

During the restoration, the Sistine Chapel remained open every day. Visitors enter the hall and admire the vaulted frescoes, but the altar wall is hidden by scaffolding. A high-quality screen with a full-size reproduction of the Last Judgment is stretched across the scaffolding. Visitors see the fresco exactly where it should be, only what they see is not the original, but a replica.

Daily attendance is limited to 24,000 people. Work is scheduled to be completed by Easter 2026, in early April.

Funding and status of the operation

The Vatican has classified the current work as "unscheduled maintenance," a term distinguishing it from a full-scale restoration. Every year, laboratory staff perform scheduled dust cleaning of the frescoes using lifts, without touching the surface. This intervention was necessary precisely because the salt deposits proved too dense for remote treatment.

The operation is being funded by the Florida branch of the Patrons of the Arts of the Vatican Museums, a private philanthropic organization that has supported the preservation of the Holy See’s heritage for decades. This arrangement made it possible to organize the unscheduled operation without months of bureaucratic approval.

Tourism, climate and systemic load

The Sistine Chapel accommodates approximately six to seven million people a year in a space measuring approximately 520 square meters. The existing climate control system was installed several years ago, but the tourist flow has since increased, and the system is operating at its limits. Following the restoration, the Vatican plans to upgrade the filtration and ventilation equipment.

The task is complicated by the space’s special status: the Sistine Chapel is a functioning liturgical space, the site of conclaves during which cardinals elect a new pope. Any technical modifications must be approved by church authorities and must not compromise the hall’s visual and acoustic appearance. This makes each engineering project a separate negotiating task.

Over the past decade, the Vatican has repeatedly discussed limiting visitor numbers. Each time, economic arguments — the Sistine Chapel generates a significant portion of museum income — were at odds with conservation considerations. The fresco’s current whitish coating made this compromise tangible and visual: thirty years of human sweat isn’t a metaphor for a threat; it’s a chemical reality on the surface of one of history’s greatest works of art.