Oil Change

Drying oils are an essential component to painting in oils, and there are several which can be used. The primary function of a drying oil is to bind the pigment particles together which enables the pigment to adhere to the surface of the painting.

The most common oil is linseed which is pressed from the flax seed and has been used since antiquity. It can be hot pressed or cold pressed or boiled or left to thicken in the sun or shaken in a bottle with sand to allow the impurities to settle.

This latter technique is called washed and is very desirable to use but very time consuming also. The most commonly used linseed is cold pressed refined. Linseed can be used as a binder to make or mull dry pigment into paint and also as a medium to alter the consistency of the paint while painting on canvas or a panel.

Another useful oil is walnut derived from the pressing of walnuts. Now, my grandson has an alergy to all tree nuts (even touching the shell can cause a life threatening reaction) so I never use it, but it is commonly found in art studios. 

Poppyseed oil is also widely used and is desirable because of the clear light color. It darkens and yellows less than linseed and therefore, is used for light colors such as white, lead tin yellow, and Naples yellow.

All of these oils contain various fatty acids and triglycerides. During the oxidation process, these small units grow into larger networks and are linked together and polymerized. These networks bind the pigment together while reacting to certain ions in the pigment, accelerating the drying process. This will eventually harden into a dry paint layer on the surface of the painting. Each drying oil can be worth its weight in gold and has a useful place in painting, and can even be changed regularly.