Zinc Plating ASTM-B-633
Zinc plating is one of the more versatile plating finishes. It can be used for corrosion resistance, aesthetics or as a paint base over the zinc plated metal. Plating thickness can be regulated for a very thin coating of .00015 to .001 for severe corrosive environments. Per the ASTM B633 Spec the thickness for zinc plating is as follows; SC 1 (.0002), SC 2 (.0003), SC 3 (.0005), & SC 4 (.001). Zinc plating can be chromated different colors after plating to achieve different results for the product. There are 6 types of conversion coatings that are available after zinc plating. Type 1 (As Plated with no chromate conversion coating), Type 2 (With a colored chromate; Customer specifies the color, (Yellow, Olive Drab or Black), Type 3, (Clear or Blue bright), Type IV (Phosphate coating), Type V (Trivalent Clear or Colorless passivate), Type VI (Trivalent Yellow or Black, Color Specified by customer).
Clear or “Blue bright”, as it is often referred to because of its blueish tint, is used as an inexpensive imitation for chrome plating. Yellow can be used as is or as a paint base. We also currently do Hexavalent and Trivalent Yellow Zinc plating. Trivalent Yellow meets automotive and RoHs specifications. Our Trivalent Black chromate is also RoHS compliant and gives a very smooth shiny black finish for decorative purposes or as an excellent corrosion resistant finish. Olive Drab is only available in Hexavalent Chromate and usually used for military applications. The Olive Drab chromate conversion coating provides a superior corrosion resistant finish to other color of chromates. As a rule, the darker the chromate, the more corrosion resistant the finish with the same amount of plated thickness.
|Hexavalent Yellow Zinc||Trivalent Clear Zinc||Trivalent Black Zinc||Hexavalent Olive Drab Zinc|
|Trivalent Yellow Zinc Examples|
Zinc Plating, because of its low cost and versatility, has many applications in industry. It has so many that it would be impossible to list them all. The bottom line with zinc plating is that if you a looking for an inexpensive corrosion resistant finish that can be used for your product, then zinc may be for you.