Ground preparation of paintings :

Layer or set of the first layers of material applied to the support to obtain a surface suitable for receiving the pigments according to the painting technique adopted.
If the preparation consists of several layers, the upper layer is commonly referred to in modern literature with the term priming.

The ground preparations of paintings on wood panels and on canvas generally consist of white calcium-based mineral substances – such as gypsum or white clay – and adhesives based on animal glues.
The quality of the materials used and the correct execution of the preparation it is essential for the conservation of the painting over time.

Positioning itself between the support and the pictorial layers, the preparation must be characterized by a correct absorbent capacity of the binder, by impermeability and elasticity, in order to respond to the expansion and contraction movements of the support, limiting the transmission of these movements to the pictorial layers.