Ask the Expert Question-and-Answer Archive

by Ron Joseph

Structural Steel Primer

Q. For exposed structural steel in Atlanta, GA that will be painted, would you recommend a zinc-rich primer and epoxy intermediate coat under the finish coat or would a good alkyd primer and high quality epoxy finish coat provide adequate (say 10 to 15 years) corrosion protection?

A. I don't think you need to use a zinc-rich primer followed by an epoxy for steel exposed in Atlanta, GA. On there other hand, I do not recommend that you use an alkyd primer followed with an epoxy, since these two resin systems are incompatible. Rather use an epoxy primer followed with an epoxy topcoat, or a polyurethane topcoat. If the topcoat will be exposed to direct sunlight you can expect the epoxy to chalk over time, but a polyurethane will retain its gloss.

Good luck,

Ron Joseph