Tung oil comes from the seeds of several species of Aleurites, primarily Aleurites fordii, a deciduous shade tree native to China. It belongs to the Euphorbia Family (Euphorbiaceae) along with the candlenut tree (A. molucanna), another species with seeds rich in unsaturated oils. For centuries tung oil has been used for paints and waterproof coatings, and as a component of caulk and mortar. It is an ingredient in "India ink" and is commonly used for a lustrous finish on wood. In fact, the "teak oil" sold for fine furniture is usually refined tung oil. Some woodworkers consider tung oil to be one of the best natural finishes for wood.
Other unsaturated plant oils, such as castor oil and linseed oil, take longer to dry and leave an oily residue until they soak into the wood surface. Tung oil 's ability to dry quickly and polymerize into a tough, glossy, waterproof coating has made it especially valuable in paints, varnishes, linoleum, oilcloth and printing inks.
Tung oil is composed primarily of eleostearic (elaeostearic) acid, with smaller amounts of oleic, linoleic and palmitic glycerides. Eleostearic acid is a crystalline unsaturated fatty acid that exists in 2 stereoisomeric forms: An alpha acid occurring as the glycerol ester especially in tung oil, and a beta acid obtained from the alpha acid by irradiation (9, 11, 13-octadecatrienoic acid). The following table shows the chemical structure of tung oil eleostearic acid: