Fresco is a technique of mural painting where water-based paints are applied directly onto freshly laid or wet lime plaster. Water is the key part of this technique and as the pigments mix with the water and the plaster begins to settle and dry, the painting becomes an integral part of the wall or ceiling. The Fresco technique has been employed throughout history and is closely associated with Italian Renaissance Painting.
The image shows part of the ‘Last Supper’ by Da Vinci. In trying to achieve greater luminosity and detail in this piece, he tried an experimental technique of painting onto dry plaster. This decision and subsequent environmental and deliberately inflicted damage means the work is now in a very poor state.