arriccio

Arriccio is the rough base coat used in traditional plasterwork and fresco painting. It is the first layer applied to a prepared wall, whether it is stone, brick, or existing plaster, and it provides a keyed, porous surface for the subsequent plaster coats and for fresco pigments. Its primary function is to stabilize the substrate, improve adhesion, and regulate moisture movement through the wall.

Composition and preparation typically involve lime putty mixed with an aggregate such as sand, sometimes with marble dust or pozzolanic additives. Fibrous materials like animal hair may be included to reduce cracking. The thickness of an arriccio varies, commonly ranging from about 5 to 15 millimeters, depending on the wall and the desired final surface texture.

Application and use in fresco: In true fresco technique, the arriccio is laid onto a damp wall and then left to set to a workable firmness. The next layer, the intonaco, is applied while the arriccio is still damp, forming a bond as the plaster sets and carbonation begins. Painting is done on the wet intonaco, allowing pigments to become an integral part of the plaster.

In addition to fresco, the arriccio serves as a general rough coat in decorative plastering and restoration contexts. It is associated with historical plastering traditions in Italy and the broader Mediterranean, and modern practice sometimes reproduces traditional mixes for conservation and stylistic fidelity.