This is based upon a recipe for a drying oil that is prepared with tung oil, which imparts hardness and fast drying, but is not suitable for oil painting. Tung oil (also called China wood oil) was used as a coach varnish in the late 19th and early 20th centuries. In this formula, we've replaced the tung oil with Natural Pigments Epoxide Oil, which has qualities similar to tung oil. VM&P Naphtha is available from most hardware stores, but other solvents can be used in its place, such as mineral spirits, but you will have to increase the amount of solvent. VM&P Naphtha should be used with some caution with dried oil paintings, because it is an aggressive solvent.
Mix all ingredients in the order listed below. They can be mixed together at room temperature, but it will be found that they will incorporate easier when heated to about 90° C.
INGREDIENTS PARTS Epoxide Oil 25.0 Vacuum-Bodied Oil (Extra-High Viscosity) 20.0 Copal Varnish 9.8 VM&P Naphtha (CAS 64742-48-9) 45.0 Cobalt drier 0.2 100.0