ZINC PLATING SPECIFICATION – BOSCH – PE-9712-31 Home › ZINC Plating › BOSCH – PE-9712-31 SPECIFICATIONS BOSCH – PE-9712-31 Zinc Plating with Chromate Dip The object of this treatment is to form a uniform continuous coating of zinc with a trivalent chromate dip on steel, iron, or brass parts to protect them against corrosion.