Leonardo daVinci’s famous “Last Supper“ (1498) is not a true fresco. Da Vinci painted on a dry wall rather than on wet plaster and chose to seal the stone wall with a layer of pitch, gesso and mastic, then paint onto the sealing layer with tempera. As a result, the painting started to flake soon after it was completed. By 1556, the painting was so deteriorated that the figures were unrecognizable. From 1978 to 1999, Pinin Brambilla Barcilon guided a major restoration project which undertook to permanently stabilize the painting, and reverse the damage caused by dirt, pollution, and previous restoration attempts. This restoration took 21 years and on May 28, 1999 the painting was put back on display. When it was unveiled, considerable controversy was aroused by the dramatic changes in colours, tones, and even some facial shapes.