Dark Drying Oil or black oil is a fast drying oil made by heating linseed oil with lead oxide (litharge) and used in historical oil painting. The lead (metal basis) content of our dark drying oil is about 3% by weight.

Black oil can improve the handling and drying of oils and can be used in recipes to make megilp, Maroger and Roberson's mediums and traditional oil varnishes, such as copal.