Specifications
Zinc electroplating is a soft, ductile, decorative, corrosion-resistant finish. In most applications, the protection is accomplished by sacrificing itself. The zinc corrodes before iron thereby protecting the base metal. For additional corrosion protection, chromates are applied over the zinc. Chromates used in the zinc electroplating process become a component of the coating. Chromate films are typically very thin, and the chromate coating provides no measurable thickness to the overall coating.

ASTM-B633-94
Type I As Plated
Type II Yellow (or specified color)
Type III Clear
Type IV Phosphate Treatment

Class Fe/Zn25 SC4 (Very Severe) 0.001 thick
Class Fe/Zn12 SC3 (Severe) 0.0005 thick
Class Fe/Zn8 SC2 (Moderate) 0.00032 thick
Class Fe/Zn5 SC1 (Mild) 0.0002 thick

QQ-Z-325-C (76) *CANCELLED 82*
Type I As Plated
Type II Yellow (or specified color)
Type III Phosphate Treatment

Class 1 0.001 thick
Class 2 0.0005 thick
Class 3 0.0002 thick