Either a bright or dull finish is acceptable. Bright zinc plating closely resembles bright chromium.
However, bright zinc does not have the permanence of surface appearance. Zinc coated steel will not rust even when exposed by scratches because of the sacrificial protection of the zinc. On weathering, zinc turns to a drab gray color. Zinc should be deposited directly on the base metal
(Nickel is permissible undercoat if base metal is a corrosion resisting steel). Parts having a hardness greater than approx. Rc-33 must be given a heat treatment prior to plating. Parts having a hardness over approx. Rc-39 must be given an after plating baking at 375ºF + 25º F for 3
hours within 4 hours after plating.