Distemper is a form of painting medium where the pigment is bound with vegetable or animal glues. ‘Hard distemper’ uses either casein (found in cows milk) or linseed oil as a binder, and is sturdy and wear-resistant. ‘Soft distemper’ is bound with chalk or lime combined with animal-based gelatenous sizing, and is easily marked, scraped, or washed off. Distemper was the medium of choice for Tibetan deity paintings, or thankas, and was popular in western medieval and Renaissance painting before the invention of oil paints.
