Affresco

Affresco is a mural painting technique in which pigments are applied to freshly laid lime plaster, so that the color becomes an integral part of the wall as it sets. The method relies on a chemical bond between the pigment and the lime in the plaster, producing a durable, unified surface. It has ancient roots in the Mediterranean world and became a major medium in Italy during the Middle Ages and Renaissance.

The typical process involves preparing a rough underlayer (arriccio), then applying a smooth, wet layer of plaster (intonaco) in sections called giornata. The artist transfers a drawn design (cartoon) to the wet plaster, sometimes using a sinopia underdrawing. Painting on the fresh surface requires speed and planning, because the pigment must be set before the plaster dries. After drying, the wall may receive additional details using lighter or drier applications, a practice known as fresco secco.

There are two main varieties: buono fresco (the pigment is painted on wet plaster and bonds chemically as it dries) and fresco secco (pigments are applied to dry plaster with a binder). Buon fresco generally yields greater durability, while fresco secco is more common for later touch-ups and restorations, though less resistant to moisture.

Affresco reached its peak in Italian art with masters such as Giotto, Masaccio, Piero della Francesca, and Michelangelo, whose frescoes adorn churches, chapels, and public buildings. Conservation of frescoes requires controlling humidity and salts, and restorations have sometimes sparked debate over historical integrity.