The basic situation of tung oil: the oil squeezed from the seeds of Euphorbiaceae trees (containing 35-50% oil), that is, tung oil (also known as tung oil or tung oil), is yellowish brown and inedible. It is an important drying oil, which is mainly used in industrial production and is a specialty of China. Tung oil is widely planted in Sichuan, Hunan, Hubei and other provinces in China, and a large amount of tung oil is exported every year. Tung oil is also cultivated in Japan and Southeast Asia, but it belongs to other varieties, and the quality of oil squeezed from its seeds is not as good as that of China's tung oil, so the oil produced by China's tung oil is generally called China Tung oil internationally.

Tung oil is directly used as coating (called raw tung oil). Although it can also be dried to form a film, the film is sticky, frosty, dull and unstable, and is often used after heat refining. China has a long history of applying tung oil, and has created and mastered the production technology of tung oil hot refining. Tung oil is heated to 260-280℃ (gelatinized for 6 minutes), and after cooling, a drier is added to make cooked Tung oil of various specifications. The oil film of cooked tung oil is fast, hard, bright, smooth, non-sticky and frost-free. Mainly used to cooperate with lacquerware to make cooked lacquer. It can be directly painted on wooden boats to make waterproof devices, such as tarpaulins and umbrellas, and can also be added with pigments to make paints of various colors, which can be painted on doors, windows, wooden furniture and so on.

Tung oil is divided into raw tung oil and cooked tung oil. Raw tung oil is used in medicine and chemical industry. Cooked tung oil is processed from raw tung oil, which can replace varnish and paint for machine maintenance, indoor wood floors, wooden ceilings, sauna boards, wooden balcony handrails and so on. Outdoor wooden floors, flower stands, wooden houses, pavilions, fences, wooden bridges, boats, chairs, etc.

Intuitively, cooked tung oil is thicker than raw tung oil, and its color is dark brown. Because the ingredients contain chemicals such as rosin and varnish. Pure oil is not too viscous. Similar to vegetable oil, no chemical irritating smell. There are two kinds of cooked tung oil, one is cooked pure tung oil and the other is mixed cooked tung oil. The extraction method of pure tung oil is fried tung oil, without artificial addition of any chemical components, which is suitable for environmental protection and pollution-free decoration, especially indoors. Mixed cooked tung oil is a kind of paint, which is prepared according to the method of 2: 2: 6. 20% varnish +20% rosin +60% tung oil is heated and boiled to 260 degrees. Tung oil boiled in this way needs to be filtered before it can be used with wood. Mixed cooked tung oil has a strong paint smell. The pressing method of tung oil is a traditional and ancient method. This method is gradually being eliminated.