How to paint extruded aluminum?

I want to paint a sliding screen door that s made from extruded aluminum, it is a very smooth surface even after sanding it with rough sand paper. I tried painting one side after sanding with 80 grit sand paper and the paint would peel off easily. What is the right way to prep the aluminum for painting? If there s... show more I want to paint a sliding screen door that s made from extruded aluminum, it is a very smooth surface even after sanding it with rough sand paper. I tried painting one side after sanding with 80 grit sand paper and the paint would peel off easily. What is the right way to prep the aluminum for painting? If there s a certain product I should get let me know what it is.
6 answers 6