Ask the Expert Question-and-Answer Archive

by Ron Joseph

April, 2005

Coating Stainless Steel

Q. I am looking at coating 304 and 316 stainless in a coil-coating line and then baking the coating onto the metal. I am also looking at coating 304 and 316 in post-application by brushing, rolling, or spraying coating. Coil sizes vary at average: 48 wide and .028 thick coil. We have had issues with epoxy coatings peeling off of the stainless, and our coating manufacturer is working on a reformulation. I looking for any recommendations of any types of coatings, coating additives, etc, that could be used to improve adhesion in both processes (coil coating and post-application).

A. I am surprised that you have had some success in this field. Applying a clear coating to stainless steel is risky at best, and then coiling or uncoiling the stainless after the coating has been baked adds to the difficulty.

I do think that epoxy coatings are probably the best in terms of adhesion (for indoor exposure), but without having seen the problem first hand I suggest that you focus on improving the pretreatment or surface preparation process of the stainless.

In my opinion, for this application a primer is a must, and epoxy coatings are the most commonly used resins for good adhesion to substrates. It is possible that other coating resins might serve you better (no guarantee), but I would need to research that for you on a fee basis.

I'm not a paint formulator and cannot help you with additives or other formulation changes. On the other hand, I consider myself an "expert" on application processes. Therefore, I tend to see if process changes will solve a problem.

If I can be of further help please call or write.

Best wishes,

Ron Joseph