There are also many exposed screws with white coating, mainly white nickel, white zinc and stainless steel screws without surface treatment.
The electroplating process is: degreasing-cleaning-weak acid activation-electro-galvanizing-cleaning-white passivation-cleaning-drying. The difference from black zinc is that there is no difference in the passivation and passivation solution. White passivation is a It is a colorless and transparent zinc oxide film that contains almost no chromium, so the corrosion resistance is worse than that of black zinc, blue zinc and color zinc. The industry standard is 6-12 hours. The specific accuracy can be achieved about 20 hours of resistance to neutral salt spray.
Due to the neutral salt spray test of the screw with white zinc surface treatment process, the surface coating is corroded and whitened initially, and the phenomenon of red rust occurs in about 40 hours, so the corrosion resistance of white zinc is better than that of white nickel. Compared with white nickel, the appearance is darker. White zinc is the primary color of zinc, which is bluish white, which is quite different from white nickel.
