The modifications of the conservation techniques follow two directions: the selection of materials for the facing, and the choice of an adhesive. The conclusion is that restoration procedures must be practices on model copies, made on a thin layer of plaster. The traditional method used for apprenticeship study of fresco technique is the following: a wooden case is filled to the edge with a solution of limestone in several layers. These frescoes are too heavy and not suited for experimentation. The procedure introduced here consists of a thin layer of plaster on a hygroscopic material, sand, felt, cloth, etc. At the end, the hygroscopic layer is removed.