The buon fresco technique consists of painting with pigment ground in water on a thin layer of wet, fresh, lime mortar or plaster, for which the Italian word is intonaco.
However, some artists used lime as a binding medium for pigment to slow the drying process of the plaster and continue working for longer periods of time.
This chemical reaction fixes the pigment particles at the plaster's surface in a protective crystalline mesh known as the lime crust.
Frescoes dating from the 17th century BC using this technique have been found in the excavations of Akrotiri on the island of Santorini in Greece, changing our beliefs about art in prehistoric times.
In medieval and Renaissance Italy, a wall to be frescoed was first prepared with a rough, thick undercoat of plaster known as the arriccio.