A network of fine cracks in a varnish or paint layer, which may be caused by several different deterioration mechanisms; e.g. different rates of drying between two layers, or the increasing brittleness of one layer relative to another.

A glaze applied to this watercolour has cracked and become cupped, causing a distinctive pattern. Photo courtesy of Artlab Australia.












The paint protected by the frame (top edge) has not developed the distinctive "dried mud" pattern. Photo courtesy of Sarah Hillary.