Drying oil
From Freepedia
A drying oil is an oil which hardens to a tough, solid film after a period of exposure to air. The term "drying" is actually somewhat of a misnomer, since the oil does not harden through the evaporation of water, but through a chemical reaction in which oxygen is absorbed from the environment (oxidation). Heat and light speed up this reaction. Drying oils are a key component of oil paint and many varnishes. Some commonly used drying oils include linseed oil, tung oil, poppy seed oil and walnut oil.
