The black treatment of the lifting chain is mainly to delay the rust and increase the aesthetics of the chain. Darkness is a kind of surface treatment. Generally, the surface treatment of the chain when making a tie will be black. The appearance is more beautiful after making it, and it is more conducive to sales. The surface treatment of the chain foundation is the primary color polishing. Of course, in addition to hacking, there are galvanized, electric swimming, carburizing, hanging plastic, sticking paint, and so on. The function is also done around delaying rust and beauty. Customer purposes are diverse and different needs. Surface treatment can be done according to customer requirements.