It can be used pure or with lime. Casein spreads cold. We talk about "casein tempera". The casein is between the acrylic paint and the watercolor. A few hours after its application it becomes completely waterproof. After drying, it deposits a hard film, very solid. It applies to plaster, wood, cardboard and paper.
It is food, but for some reasons of storage (not food standard), it is unfit for consumption.
