Black Oil is a fast-drying oil medium processed from linseed oil and used as an oil painting medium. It can be added to other oil mediums (up to 50%) to accelerate the drying time of the paint. It is suitable for medium to dark color paints due to the dark color of the oil itself. It is made according to a traditional recipe of adding silver white (1.5%) to linseed oil (98.5%) and boiling it at about 220°C for several hours.