What is Tung Oil?

Pure Tung Oil

Tung oil or China Wood Oil is arguably the best natural finish for wood. In over 100 years of development of synthetic resins and varnishes no one has developed a coating that surpasses the overall performance of natural tung oil.

Tung Oil is a drying oil obtained by pressing the seed from the nut of the tung tree (Vernicia fordii). As a drying oil, tung oil dries upon exposure to air. The resulting coating is transparent, waterproof, and flexible, a property exploited in most of its applications, which include wood finishing and the composition of traditional oil paints caulks, mortar and india ink. Tung oil is used on wooden toys as it is naturally non-toxic when dry and is not affected by mould like linseed oil. Tung oil is able to move and flex as wooden surfaces expand and contract with age and changing temperature.

The Chinese have utilised the properties of tung oil for hundreds, if not thousands, of years, for caulking and painting of their boats, treating leather, and waterproofing paper and cloth.

The tung tree originated in central and southern China, concentrated around the Yangtse River. and appear in the writings of Confucius from about 400 B.C.

Other unsaturated natural plant  drying oils, such as linseed oil or castor oil take longer to dry than tung oil, and do not penetrate as well, leaving an oily residue until they soak into the wood surface. Tung oils natural ability to dry into a tough waterproof finish has made it especially valuable.

The name ‘Tung Oil’¬† is often used by paint and varnish manufacturers as a generic term for any wood finishing product that contains real Tung oil and/or provides a finish that resembles that obtained with it. Care should be taken when buying ‘tung oil’ to make sure it is pure tung oil, without other added oils, solvents or driers.

Tung oil is composed primarily of eleostearic 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).