A fresco is a type of wall painting. The term comes from the Italian word for fresh because plaster is applied to the walls while still wet. There are two methods of carrying out fresco painting: buon fresco and fresco a secco. For both methods layers of fine plaster are spread over the wall surface. The penultimate layer is called the arriccio, and the cartoon is drawn on this. The final layer of very smooth plaster is called the intonaco.
In buon fresco the paint is applied to wet intonaco, and only as much plaster as can be painted in one day is spread on the wall. This method bonds the fresco to the wall. Each day's work is called a giornata. In fresco a secco the paint is applied dry, either on top of the buon fresco, which has dried, or on a dry intonaco.
The technique for detaching frescoes and transferring them to a new support has been known since at least the 16th century.