Tung oil or China wood oil is a obtained by the from the of the Vernicia fordii. Tung oil hardens upon exposure to air, and the resulting coating is transparent and has a deep, almost wet look. Related drying oils include , , and oils. The oil and its use are believed to have originated in ancient China and appear in the writings of from about 400 B. Raw tung oil tends to dry to a fine wrinkled finish; the US name for this is gas checking: this property was used to make wrinkle finishes, usually by adding excess cobalt drier. The tung oil tree originates in southern China and was cultivated there for tung oil, but the date of cultivation remains unknown. During the Song Dynasty, tung oil was used for on ships. Tung oil is etymologically derived from the Chinese tongyou. The earliest references for Chinese use of tung oil is in the writings of Confucius around 500 to 400 BC The Chinese have used tung oil, also known as China wood oil, for at least 2500 years for building waterproof boats and paper parasols, wood finishing, wood waterproofing, caulking, inks and paints. The major in tung oil and their concentration are listed in the table. Major fatty acid composition of tung oil 82. They are especially sensitive to which encourages of neighbouring chains and hence hardening of the base resin. Showing the golden effect of polymerized tung oil versus bare wood. This is why it is used on boat decks and now on floors. The oil is often diluted with hydrocarbon thinner so that the is very low and enables the oil to penetrate the finest grain woods. This thinning vehicle evaporates within 15 to 20 minutes and results in a totally green residual finish. Tung oil resists liquid water better than any other pure oil finish and does not darken noticeably with age and is claimed to be less susceptible to mould than. Most importantly, of all the oil finishes, tung oil is the only drying oil that will polymerize 100% completely harden. Linseed oil, for example, never completely hardens. The product packaging will usually clearly state if it is pure tung oil. Heating tung oil to about 500 °F 260 °C in an oxygen-free environment will substantially increase the viscosity and film-forming quality of the product. Most polymerized tung oils are sold mixed with mineral spirits to make them easier to work with. The traditional technique for applying pure tung oil is to dilute the oil 1:1 with solvent, then apply a succession of very thin films with a soft, lint-free, non-fuzzy cloth such as tee-shirt cotton. Diluents range from traditional spirits of to any of the new thinners to. The choice of thinner should be guided by how fast the coating needs to set. Naphtha works well in spray-on applications in well ventilated studios. Primary coats may be laid down at a 1:1 oil-to-thinner ratio, and successive layers, if not absorbed into the wood, at higher solvent to oil concentrations. This technique brings out the deepest color of the wood while maintaining a finish. Tung oil finishes that start with oils or tung oil preparations are best applied in the principle: thinned pure oil is applied to deeply penetrate the surface, to fill pores. Straight oil is then applied moderately to adhere to the surface and provide a good base for the thick gloss layers. The polymerized oil is then applied thickly as a single layer, allowed to fully dry, is buffed smooth with very fine , then 0000. The surface is wiped clean with a moistened rag, then allowed to dry. A final coat is applied fairly thickly the oil will smooth itself into a glass-like coating and allowed to dry for two to three days. Rags soaked with tung oil can spontaneously combust burst into flame. The Origins of Chinese Civilization. University of California Press. Retrieved 5 October 2012. AOCS Press published March 8, 2016. American Association of Woodturners. Archived from on 2015-05-15. CS1 maint: Archived copy as title.
