Insoluble sulfur is a transparent, amorphous chain like elastic sulfur obtained by heating sulfur powder to boiling (444.6 degrees Celsius) and rapidly cooling it in cold water. It can also be prepared by diluting superheated sulfur vapor with inert gas and spraying it in cold water mist to cool to below 90 ℃, or by dissolving sulfur block in ammonia and immediately spray drying. Due to the majority (65%~95%) being insoluble in carbon disulfide, it is called insoluble sulfur. Due to its insolubility in rubber, it is less prone to early vulcanization and sulfur spraying in the rubber material, which does not affect the adhesion of the rubber material. Therefore, it can eliminate the coating process, save gasoline, and clean the environment. At the vulcanization temperature, insoluble sulfur transforms into the usual sulfur to exert its vulcanization effect on rubber. Generally used for particularly important products, such as steel wire tires.