by Ron Joseph
Painting Over Powder Coating
Q: I have a NEW awning with an aluminum frame. It has a beautiful, shinny cream color powder coat finish. Too bad my wife dislikes the color. I plan to over paint the frame a dark brown color. Many portions of the frame have recesses, bosses, etc., which are difficult to 'rough up' with sand paper. I'm thinking wash primer. Is this a good choice? Is there a better type of liquid primer or method to prepare the irregular frame surfaces? Help!
A: In my opinion a wash primer will do more harm than good. It would be ideal if you can scuff sand the powder coating to a dull finish and then apply a two-component epoxy primer followed by a two-component polyurethane or a single component acrylic topcoat. However, you would need to be very aware of the potential health hazards of working with the two-component coatings. YOU MUST READ THE VENDOR'S INSTRUCTIONS AND FOLLOW THEM! Also, most of those that are available are intended for spray application and not brush. Since you presumably intend to keep the awning for many years, this system would give you long term performance in an exterior environment.
A safer alternative is to scuff sand as before and apply an exterior acrylic latex system, because these coatings are also known to have reasonably good exterior weathering durability. I do not believe that the acrylic latex system is as durable as the epoxy/polyurethane system that I suggested.
A third alternative is to apply an epoxy primer (as before) followed by an exterior acrylic latex.
Do not apply only an epoxy primer/topcoat system as epoxies do not retain their gloss levels well when exposed directly to sunlight. It is OK to use an epoxy as a primer so long as you apply an opaque topcoat over it.
If you don't want to scuff sand the powder coating then you run the risk of paint delamination down the road. Maybe you can hire an unemployed laborer to do the scuff sanding while you sit on your porch and relax. Alternatively, if the awning has not already been installed you might consider having it repainted by a local custom coating shop that knows how to apply two-component coatings properly.