Black zinc plating is a non-standard screw anti-oxidation production and processing method, suitable for hardware products such as machining, stamping, aluminum die-casting and other process products.

The non-standard screw black zinc plating refers to a process of solving the problem in a chromic acid solution on the galvanized layer to obtain a rainbow colored coating. The structure is generally considered to be a complex mixture of basic chromium chromate, basic zinc chromate, chromium chromate, zinc chromate and its metal oxides of zinc and chromium. The passivation of the galvanized layer into rainbow color through stainless steel can further enhance its corrosion resistance. Mainly used for safety protection of steel products.