Levkas - this is base substance that is made of chalk, oil and gelatin in certain proportions and is placed on wood or other surface for painting.
Traditionally used in Icon painting.
The whole process takes one week.
Every day 1 or 2 layers of levkas are applied.
I usually made levkas for those wood boards and other surfaces that I make by myself, find good pieces of wood in the forest. On stones also, if the surface needs.