Ask the Expert Question-and-Answer Archive

by Ron Joseph

March, 2004

Powder Coating Stainless Steel

Q. Which pretreatment of stainless steel did you recommend before applying & curing powder coatings? Are there primers available on the market or is it necessary to use wet chemical treatment?

A. Powder coating stainless steel is risky at best, and I would be very cautious. Clearly, the type of stainless steel might also makes a difference, in that a #304 stainelss might give better adhesion than a #316 stainless.

If I were to powder coat stainless steel I would want to acid etch (wet process) or scuff sand (mechanical process) to provide some mechanical adhesion. Passing the stainless steel through a phosphate pretreatment system would thoroughly clean the surface, but the phosphate would probably not have much of an effect. The main purpose of the wet preparation is that in an acid environment you might achieve some degree of etching.

On a fast moving production line you probably would not want to scuff sand the surfaces because it is a time-consuming process.

To the best of my knowledge there are no primers that you would want to apply before applying the topcoat.

I hope this helps.