It is highly likely that when Leonardo’s Last Supper is unveiled to the public early next year after a twenty-year conservation campaign, many people will think that it looks much worse than before. The sad fact is that no more than 50% of Leonardo’s original paint surface survives and previously we were looking at an eighteenth-century repainting.
While Leonardo’s hallowed status in the art-historical hierarchy makes any intervention on his works highly controversial—the Louvre, for example, has announced that it will not be taking the layers of yellowed varnish off the Mona Lisa (The Art Newspaper, No.84, September 1998, pp.10-11)—the conservation of The Last Supper in the refectory of the Dominican monastery of Sta Maria delle Grazie in Milan was urgently needed to counteract a progressive deterioration of the fresco’s surface.
The project has been coordinated by the Soprintendenza of Milan with the Istituto Centrale del Restauro in Rome. When it was launched, Carlo Bertelli, then director of the Istituto Centrale del Restauro, declared its aim to be the discovery of “the real Last Supper”. Over the years work has been stopped repeatedly, sometimes following changes at the helm of the Milanese Soprintendenza and the Istituto in Rome, other times simply to allow the whole project to be reconsidered.
It was in 1978 that Pinin Barcilon Brambilla was conserving a Crucifixion on the wall opposite the Last Supper and she noticed that fragments of paint were peeling off Leonardo’s work before her eyes. She went on to be appointed the restorer in charge of conserving this world-famous painting.
According to Dr Brambilla, the fresco’s deterioration was due to various factors: “In the Last Supper, Leonardo experimented with a new technique. He painted on a layer of dried gesso spread on the wall, as if he were painting on panel [fresco painting is usually applied onto wet plaster so that as the plaster dries, the paint becomes part of the wall and is virtually indelible].
“As the layer of gesso contracted, the paint detached itself from the wall and within the artist’s lifetime, the colours had already faded. Leonardo had an extremely modern outlook; he was interested in the immediate effect and not too bothered about how long things lasted.
“The damage caused by atmospheric humidity and exposure to the elements was also extensive. In the sixteenth century the refectory was flooded for several days. In the eighteenth century, it was occupied by Napoleon’s troops. In 1943, bombing destroyed the right wall of the refectory and the Last Supper remained exposed to the elements. Finally, the various restoration projects over the centuries had totally altered the fresco’s appearance.”
The first of eight documented interventions on the Last Supper took place in 1726, when Michelangelo Bellotti was called in by the Dominicans to revive the faded colours. Bellotti scrubbed the surface with caustic soda, then varnished it with oil and repainted much of the work.
Three restorations after Bellotti’s also involved heavy repainting so that, according to Pietro Marani, co-director of the restoration since 1993, “The fresco the world has seen hitherto was essentially an eighteenth-century recreation”.
Wherever possible these layers of thick overpaint have been painstakingly removed and the limpid clarity of Leonardo’s original colours restored, but Dr Marani estimates that no more than 50% of the painted surface can be considered to be by the artist himself.
The cleaning was extremely difficult because the contracting layer of gesso caused the colours to redistribute themselves in little concave clusters on the wall’s surface. These were cleaned one by one using magnifying lenses and surgical instruments.
Traces of glazing, Leonardo’s original finishing touches, have been discovered on Matthew’s robes, and remnants of gold leaf decoration on the collar of Judas’s robe. Traces of a millefleurs pattern, similar to that on fifteenth-century tapestries, have been found on the dark curtains that flank the central table, and the windows in the background now open onto a luminous, mythical landscape.
Although the original coffered ceiling has been entirely lost, on the right portion of the fresco, Leonardo’s incisions have been discovered underneath the layers of paint. They reveal that he originally intended to have fewer ceiling panels with more space between them, a discovery which revolutionises our understanding of Leonardo’s perspective.
But the most striking results have been achieved with the faces of the figures. When painting these, Leonardo used lots of white, the longest lasting colour because its chemical make-up is the most binding.
As the layers of overpaint came off, the original faces of Christ and His apostles, unseen since the eighteenth century, emerged. Dr Brambilla says, “Only now have we discovered the original features of the faces. 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, and the actual dimensions of the heads had been changed.”
As well as uncovering all of Leonardo’s surviving paintwork, the restorers have made the fresco legible by lightly repainting unclear sections in soluble watercolour that can be easily removed with water.
Taking away the overpaint in the portions of the fresco where Leonardo’s work has survived has averted the risk of condensation in the spaces between the artist’s original pigment and the successive layers of paint, according to Dr Brambilla, but she believes that the Last Supper will still need to be constantly monitored. “The layers of repainting are no longer protecting the original paint. We must do everything we can to look after it.”
The project was funded by the State from 1978 until 1982, when Olivetti, the computer firm, became sole sponsor of the restoration.
Who did what
1726 Michelangelo Bellotti extensive repainting
1770 Pietro Mazza removes Bellotti’s repainting to replace it with his own
1821 Stefano Barazzi makes an unsuccessful attempt to detach the fresco from the wall
1853 Stefano Barazzi undertakes an extensive restoration during which the lunettes are uncovered
1901-08 Luigi Cavenaghi undertakes restoration
1924 Oreste Silvestri fixes the edges of the flaking fragments of paint
1951-54 Mauro Pelliccioli fixes the surface without removing overpainting
1978-98 Pinin Barcilon Brambilla uncovers Leonardo’s surviving paintwork and consolidates the painted surface
Originally appeared in The Art Newspaper as 'A wreck—but at least an authentic wreck'