A Timeline of Destruction

Year Event
1517 Antonio de Beatis records the painting is "beginning to decay" — barely two decades after completion.
1532 Gerolamo Cardano describes it as "blurred and colorless."
1556 Giorgio Vasari calls it "a muddle of blots."
c. 1652 Monastery residents cut a doorway through the lower center of the painting, destroying Christ's feet and sections of the foreground.
1726 Michelangelo Bellotti fills cracks with oil paint and varnishes the entire surface.
1770 Giuseppe Mazza scrapes Bellotti's additions with iron tools, then extensively repaints before being fired amid public outrage.
1796 Napoleon's troops use the refectory as a stable and armory, reportedly throwing stones at the apostles' faces.
1800 A flood submerges the refectory in two feet of water for fifteen days, generating thick green mold.
1821–1823 Stefano Barezzi attempts to detach the painting from the wall, believing it is a true fresco, and badly damages the center before realizing his error.
Aug 15, 1943 A 4,000-pound RAF bomb detonates approximately 80 feet from the painting, collapsing the refectory's roof and east wall — but preemptive sandbag and steel-tube protection saves the north wall bearing the mural.
1947, 1951–54 Mauro Pelliccioli applies shellac fixative and uncovers approximately two-thirds of Leonardo's surviving original paint from beneath restorers' overpaint.

The Physical Enemy: Moisture

The building itself conspired against the painting. The refectory's north wall is a thin exterior wall of rubble-filled masonry, ordered by Sforza in haste. It sits in a low-lying area of Milan prone to dampness, with reports of an underground stream beneath the monastery. Moisture migrated through the porous wall, dissolved masonry salts, and upon evaporation at the painted surface, deposited crystalline efflorescence that exerted mechanical pressure sufficient to lift and crack paint layers.

The Brambilla Barcilon Restoration (1978–1999)

The definitive modern restoration, led by Pinin Brambilla Barcilon, consumed approximately 22 years and 38,000 hours of work, funded by an $8 million Olivetti sponsorship.

Methodology

Brambilla's approach combined advanced imaging with painstaking manual work:

What the Restoration Revealed

The restoration uncovered details that previous campaigns had systematically altered:

"The position of the eyes had been altered; mouths that were partially open had been closed; beards that Leonardo never painted had been added; hands had been elongated and flattened."

Original discoveries included:

The Controversy

The restoration provoked fierce and still-unresolved debate:

James Beck of Columbia University, co-founder of ArtWatch International, estimated only 18–20% of original Leonardo paint survived and called the restoration "an affront."

Michael Daley of ArtWatch UK published detailed photographic critiques arguing that claimed "recoveries" were actually "adulterations."

Conservator Maurizio Seracini stated: "You don't decide to restore a masterpiece like the Last Supper on the basis of what you see under a microscope."

Leo Steinberg quoted Jonathan Swift in sardonic response:

"Last week I saw a woman flayed, and you will hardly believe how much it altered her person for the worse."

— Jonathan Swift, as quoted by Leo Steinberg

The Survival Estimates

Estimates of surviving original paint vary drastically among experts:

Expert Estimate
Carlo Bertelli (initiated the project) ~20%
James Beck (ArtWatch) 18–20%
One academic calculation 42.5%
Giuseppe Basile (ICR coordinator) "about half"
Pietro Marani (co-director) "no more than 50%"

Defenders countered that the restoration revealed Leonardo's authentic chromatic vision for the first time in centuries and that the neutral watercolor infills are fully reversible — meaning future generations can undo the work if better methods emerge.