The decorations in Pompeii
The technique of fresco decoration consisted of painting on a layer mixed of lime and marble dust, which was spread right before starting to paint and thus still wet. Seven preparatory layers could be spread one after the other on the dry wall. This served to smooth away roughness and to isolate the wall from dampness. Before applying the last layer, the most expert painter in the group traced the basic outlines of the design on the wall, which were then elaborated and finished by the parietàrii and the imaginàrii, proceeding from the top down. The pìctor imàginarius was in charge of the pictures and figurative motifs.
In 1882 August Mau, referring to the painted evidence preserved in Pompei, attempted in a treatise to distinguish the decorations in four different styles corresponding to four periods.
