This process is a low cost cobalt dark black gun process which can reach the Oeko-Tex Standard. Co<2+（in the solution） 2g/L,the layer is black and beautiful，it can reach the extreme limit of cobalt（1ppm）of Oeko-Tex Standard. The deposits is low cost tin-cobalt alloy, it still have the effect &ldquo;low cost, no needle detector beeping&rdquo;of the last generation product(707 low cobalt gun black) This process can be plated fast and the throwing is good. It only have three items, the operation is very easy. The plating time is only 40-60 seconds for rack plating, the production is three times than traditional process under the same equipment. It can operate under normal temperature, the solution is low carbon and no pungent odor. The deposits is soft and the adherence is good.