Ask the Expert Question-and-Answer Archive

by Ron Joseph

October, 2003

Difference between Zinc Plate, Zinc Chromate and Dichromate

Q. Would you please let me know the difference between the following three surface finishing processes? Zinc plated, Zinc chromate, Dichromate Thanks very much!

A. Zinc plating is an inorganic metal coating that is deposited on a steel using an external electric current. It is similar to galvanizing.

Zinc chromate is usually an organic primer paint that can be spray or brush applied over steel, galvanizing or even zinc plating.

Dichromate is a sealer that is deposited on an inorganic plating, such as zinc plating. It is very thin and in itself does not provide much corrosion resistance. However, when it is deposited onto a metal, such as zinc plating, it enhances the corrosion resistance and is an excellent base of a paint that can be applied over the plating.

Hope this helps.