Q:

I am re-siding and painting my house. My windows are all fitted with storm windows and screens that are housed in unpainted aluminum channels. I would like to paint the aluminum channels to match the rest of the trim. What is the correct way to paint aluminum so that the paint doesn’t peel in the extremes of our weather?

Scott Kent, Bradford, NH

A:

Victor DeMasi, a painter in Redding, Connecticut, replies: I’ve painted thousands of aluminum house components over the years and have never had a callback. With most painting projects, surface prep is the key to years of maintenance-free service. Aluminum that has been exposed to the weather for some time oxidizes, which leaves the exposed surface white and pitted. If the oxidation is only slight, the aluminum can be painted directly. However, if the pitting is heavy from many years of exposure, a sanding or wire brushing is needed to remove the powdery oxidation and to smooth the surface. Sanding should be done with high-quality black emery paper with the grit chosen according to the roughness of the surface. I like to use #160 emery paper. While sanding the frames, take care not to rub the window pane with sandpaper, which can leave unsightly scratches.

Before painting, the surface should be cleaned with a toluene-based surface-prep solvent such as Wilbond. Then the aluminum should be painted immediately with a high-quality exterior oil-based enamel. No primer is necessary, but at least two coats of the finish paint will be needed. The paint should be applied with a brush to avoid having to mask off all of the glass or be left with the big pain of cleaning the overspray. To keep your newly painted storm windows operating smoothly, avoid getting paint in the window tracks.