Can aluminum siding be painted is a question that has been asked since it was introduced to the housing industry back in 1947. The original paint on aluminum siding has a tendency of fading and turning chalky.
If you would like to paint your aluminum siding, the most crucial thing is to get it properly cleaned. The best way to do this is to spray it with a mixture of water and TSP (tri-sodium phosphate) and then pressure wash the entire surface.
Using a good acrylic latex paint that is designed for painting metal is your best option.
Once everything is clean and dry, you’re ready to apply your primer. Here’s where a lot of people make a mistake and, unfortunately, I’ve even heard of “professional” painters who do this. They apply a latex primer.
This is probably the worst thing you can do when painting aluminum siding. Most latex paint has ammonia in it, and that includes primer. Ammonia has a chemical reaction to aluminum, which produces a tiny amount of gas.
Latex paint, by nature, is very elastic, so you end up with an elastic coating with gas bubbles underneath it. If you don’t quite see the problem here just think about how your own insides react a couple of hours after eating two or three bean burritos . . . ’nuff said, right? The gas build-up under the latex primer pushes up and out, which bubbles and flakes the top coat, in other words, it causes the paint to fail.
As with any painting job, do not paint aluminum siding in the direct sunlight or extreme hot or cold, due to it’s expansion and contraction rates.