Linseed oil cooked at high temperatures to favour the process of polymerization, that is to accelerate the drying process. In the past, it was prepared in lead recipients or directly enriched with lead salts, of cobalt and magnesium, which are noted for their siccative properties. Even though it dries much more rapidly than raw linseed oil, it is not commonly used in painting, as it is much darker than the raw oil.