Ask the Expert Question-and-Answer Archive

by Ron Joseph

November, 2003

Painting Raw Aluminum Louvers

Q. We have raw aluminum fresh air intake louvers on the west side of a school building in Yuma AZ, HOT in summer. We need to paint them to match the metal building wall panels. What preparation do we need? What type of paint do we use that will hold up under extreme hot weather conditions?

A. The key to a successful paint job is the surface preparation. How do you intend to prepare that aluminum surfaces? Will you be removing the louvers from their frames? Ideally, you would have the louvers prepared by a custom paint shop which caters to the surface prep of aluminum. The louvers would be immersed in a series of chemical tanks so that a conversion coating can be applied. If you can't do that, then your next best strategy is to apply a wash primer that has been formulated for aluminum. Do not use a formulation that is designed for steel as the acid content is too high. Your paint vendor will tell you how to modify the wash primer for aluminum surfaces.

You cannot apply the wash primer by brush and must use a spray gun. Follow the application instructions on the can as this can be a tricky application.

For the topcoat I would simply use two coats of an exterior acrylic latex paint.

The longevity of the paint job will be dependent on both the surface preparation and the adhesion that is achieved between the acrylic latex and the wash primer or conversion coating.