One of the most reliable signs to distinguish antique from recent production, is given by the network of cracks that develops over time on the paint layer.

In oil paintings cracks usually develops after 60 to 120 years and usually make their first appearance in the whites.

Mineral pigments used until the beginning of the XIX century were obtained by hand grounding metal oxydes and minerals in general. Thus Old Masters pigments are characterized by the inclusion of small grains. Indeed since the colour's hiding power is inversely proportional to the size of pigment's grains, in modern colours grains are almost invisible.