Kolner Burnishing Clays are made from the finest English clays and are used at room temperature. Unlike traditional clays (bole), they are pre-mixed and there is no need to add glue or adhesives. Several layers are applied in the same manner as gesso and traditional clays and then polished to produce a lovely smooth luster. The listed colors can be mixed with each other to create additional colors. Kolner clays can also be used as a base for oil size gilding.