We have been asked by homeowners over the years whether you can paint over aluminum gutters and trim materials. Obviously, answer is “yes” but the question should have been “successfully paint”. However, the key to repainting aluminum gutters and down spouts is to clean the gutters and use the right primer. Now it is time for the bad news. Pressure washing gutters and downspouts and the rest of your exterior alone is simply not the best way to start. We have had very good results using muriatic acid. We typically will make a dilution of 8 oz acid with 128 oz water (1 cup:1 gal) in a bucket being very careful when handling the chemical.
Be very careful when using this method. DO NOT breathe in the fumes ESPECIALLY while on a ladder and wear heavy duty rubber gloves to protect your skin and protection in the form of goggles for your eyes.
Avoid using any latex paint primer that contains ammonia. Ammonia is often listed on the paint can label or a technical sheet that the paint store has on file. Ammonia can react with oxidized aluminum inside small pin holes or bare spots on your gutters and downspouts. We also recommend Sherwin Williams aluminum primer. It claims that it sticks to metals. The DTM Wash Primer is a low VOC, wash primer free of heavy metals and mineral acids. It is designed to be applied over aluminum. Make sure your bonding primer actually penetrates the chalky aluminum.
You can also use a good paint made to paint over aluminum like Sherwin-Williams Exterior Duration. These products have excellent longevity and we know looks is the name of the game. You’ll want to apply 2 coats. You should also select a color which is the same or lighter than the original aluminum. Painting darker could cause too much heat to be absorbed into the metal resulting in buckling of the aluminum. Since aluminum will expand and contract more than wood with temperatures, you need a paint that is relatively flexible. So, can you paint over aluminum gutters and trim materials? Yes you can. Good luck!