Casein is a type of aqueous paint made from the protein of milk, which can be applied to any rigid, non-oily surface such as wood, plaster, heavy watercolor paper, canvas, or linen. It is thinned with water and dries quickly to a matte, durable and permanent finish.

William Barnes was a finalist in the January 2007 issue of the American Artist’s casein art competition with this 9.25 x 9 inch casein painting.

Casein painting has been around since prehistoric times, but its popularity took a hit with the rise of acrylics.

Casein painting techniques

Casein paint can be used as a fast-drying underpainting for oil glazes, or mixed with other mediums, as demonstrated in our tutorial on how to paint water with acrylics. However, when using casein, be sure to use a rigid surface, because it becomes brittle when dry. While it may be used on stretched canvas, only a thin coat should be applied to prevent cracking.

Because of the way it is produced, casein is alkaline on the pH scale, which entails that only pigments that are stable in a high pH environment should be mixed with the medium. It also means that artists should avoid prolonged skin contact with the medium.

See also: Mixing casein with acrylics, shellac, binder

The Three Trees by Rembrandt, 1643, etching with burin