The Last Supper was an experiment that went badly wrong. Leonardo didn’t follow the established practice for painting on walls, which was to apply the paint to wet plaster, so that the two dried together. Instead, he painted directly onto dry plaster, with catastrophic results. The Last Supper started to peel soon after it was finished and within sixty years Leonardo’s biographer, Vasari, reported that it was ‘ruined’.
Subsequent attempts to restore the work resulted in additional layers of colour being added, which became dirty both over time and through mistreatment.
Then in 1972, a major restoration was embarked upon. It lasted twenty years and cost £5 million. The approach was very bold. All the paint added by earlier restorers was removed, leaving large bare patches, which were then painted with water colour. This produced a deliberate contrast between the cleaned flakes of original paint and the areas of water colour, making it obvious who did what.
Last Supper before restoration
Last Supper after restoration
The colours that emerged from this restoration are much lighter than before but have been criticised by some commentators, who prefer the pre-restoration version.
Images of Christ and other figures, before, during and after cleaning, can be found on the Chicago Press website.
You can book your 15 minutes in front of Leonardo’s Last Supper through Teleart. The earliest you can book for is usually three months from the current date.