Drying Oils
Tung Oil, also known as Chinawood or Chinese Wood Oil, is one of the most important vegetable-based drying oils in the world. It is grown in and exported from Argentina, China and Paraguay. Traditionally, Chinese tung oil has been darker in color than the tung oil of South American origin. Until recently, lighter-colored tung oil, which is preferred in the United States, has been available only in limited quantities from China. The Chinese once used tung oil in various industries such as caulking Chinese junks, waterproofing of shoes, silks and umbrellas, and the manufacture of soap and varnish. China’s traditional outlet for its tung oil was Japan and Europe. With the increased availability of light colored oil from China, U.S. imports from China have increased. Japan’s main use of the oil was in the manufacture of electronic circuit boards. The oil is still used for this purpose in other circuit board producing countries.
Although other drying oils can be substituted for tung oil, tung oil’s unique properties make it the preferred drying oil in the manufacture of paints, resins, coatings and inks, as well as an excellent finishing agent for, and waterproofing of, raw wood, concrete and wall boards.
Linseed Oil is the oldest known drying oil in the Western hemisphere. Its long standing usage in certain applications has made its displacement by other drying oils nearly impossible. As with tung oil, linseed oil is used in the manufacture of paints, varnishes, enamels, lacquers, stains, printing inks, furniture polishes and wall boards. Raw Linseed Oil is made from the crude oil removed from Linseed or flax seed by solvent extraction. This oil has been degummed and filtered. Refined Linseed Oil is produced by alkali refining, bleaching, and filtering the crude linseed oil. Boiled Linseed Oil is a combination of raw linseed oil and metallic dryers.
Castor oil is a lubricant but when its molecular structure is changed by a catalytic treatment, it becomes a drying oil. The resulting product, known as Dehydrated Castor Oil, is lighter in color than tung oil or linseed oil. It can be used to improve the quality of house paints, enamels, caulks, sealants and inks. The oil also works well to produce clear varnishes and hard finish coatings.
Dehydrated castor oil can be converted to Dehydrated Castor Fatty Acids by hydrolysis and distillation. It can be used, among other things, in the manufacture of alkyd resins, certain can coatings, appliance finishes, primers and inks.