Silicone oil is the common name for polydimethylsiloxane. The structure of silicone oil is very stable, not easy to degrade, and not easy to react with other substances under normal conditions. At the same time, the chemical bonds are flexible, easy to move, and have low surface tension, so smoothness is its most common property. In addition, silicone oil is also waterproof and breathable, and is an indispensable material in all walks of life. Organic silicon compounds began to be used in cosmetics in the 1950s, and began to be used in shampoos and body deodorants and antiperspirants in the 1970s. It has developed rapidly and has become one of the most widely used raw materials in shampoos, conditioners, various skin care products and makeup. In addition to polydimethylsiloxane itself, the organic silicon compounds involved in cosmetics and personal care products also include various derivatives, such as polydimethylsiloxane alcohol, amino dimethylsiloxane, and phenyl trimethicone commonly used in hair products; cyclopolydimethylsiloxane, polydimethylsiloxane copolyol, alkyl polydimethylsiloxane and silicone resin commonly used in skin care products and makeup. Various types of organosilicon compounds have a wide range of viscosities. For example, linear silicone oils have a viscosity as low as 5 CST [CST is the unit of kinematic viscosity, which is the abbreviation of Stokes. When the dynamic viscosity of the fluid is 1 poise and the density is 1g/cm3, the kinematic viscosity is 1CST], and there are series of products ranging from hundreds of thousands to millions of CST.