Ask the Expert Question-and-Answer Archive

by Ron Joseph

January, 2005

Painting Galvanized Surfaces

Q. I need to paint some galvanized plenums. What primer should I use for best adhesion? I'm thinking zinc oxide. Is this right?

Zinc oxide or zinc chromate primers should do the trick, but more important than the pigmentation is the coating resin. You should NOT use an alkyd resin as it will react with the galvanizing and form a soap-like chemical at the interface between the coating and the metal. Ultimately, the coating will fail due to loss of paint adhesion. Failure will be in the form of peeling, or delamination . On the other hand, you can use and acrylic or epoxy primer that contains the corrosion inhibitive pigment, such as zinc oxide or zinc chromate.

Best wishes,

Ron Joseph