Zinc


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. Below is the most common specification for zinc plating.

ASTM B633

Type I – As-plated without treatment

Type II – With colored chromate treatment

Type III – With colorless chromate treatment

Type IV – With phosphate conversion coatings

Class Fe/Zn 5 – Service Condition 1 – 5 um (.0002”) Thick

Class Fe/Zn 8 – Service Condition 2 – 8 um (.0003”) Thick

Class Fe/Zn 12 – Service Condition 3 – 12 um (.0005”) Thick

Class Fe/Zn 25 – Service Condition 4 – 25 um (.001”) Thick

For information on eliminating hydrogen embrittlement per ASTM B633, click here