Clearcoats for Brass

Q. My company produces decorative brass items for outdoor use. The items are not handled after they are mounted on an exterior wall. We polish and buff the items and then degrease them before coating. Our clear coating is an acrylic polyurethane. The brass is oxidizing underneath the coating in within a year of outdoor exposure. Can you recommend a coating that will provide a longer life for outdoor decorative items? We thought we were home free when we chose the acrylic polyurethane. C. S.

 

A. I am surprised that your acrylic urethane coated products tarnished in less than a year in service. Based on experience with outdoor applications, I would have expected them to last four or five times longer.

Looking for trouble sources other than the coating itself, if your cleaning step was inadequate, your clear coat would lose adhesion. Since you mention tarnishing and not peeling, we can rule inadequate cleaning out. I believe your problem is with the specific coating. All acrylic urethane coatings are not created equal. If I were you, I would not be satisfied until I tried other supplier’s materials.

The other approach to consider is to electrocoat the brass items. Durable clear coatings are being applied by e-coat. Finally, you should also consider powder coatings.