Why does cracking occur in Gouache painting?

The opacity and matt finish of Designers Gouache is thanks to the high level of pigment used in its formulation. As a result, the proportion of binder (gum arabic) to pigment is lower than in Winsor & Newton watercolours.

Cracking can usually be attributed to one of two things when using gouache:

1. If insufficient water is used to dilute the colour, the thicker film may crack as the paint dries on the paper (note that the amount of water needed will differ with each colour).
2. If you are painting in layers, the later ones may show cracking if the under layer absorbs binder from the wet colour.