Aluminum painting guy here. Do you know how you spell "PAINT" when it comes to aluminum? Omit the letter "T" a the end of the word. PAIN!
I cannot stress how important following correct prep procedure is when painting aluminum. Failure to do so will result in a blistered, failed paint system in less than a month or two.
1.) Sand the entire surface with 100 grit. Preferably sand blast.
2.) Using a new paint brush, wet the entire surface with diluted
ALUMIPREP NO. 33 from Aircraft Spruce. Once every inch of the surface has been etched it should be gleaming white clean aluminum. This is what real aluminum looks like. Rinse off the Alumiprep and *keep the substrait wet until done with the next step*. If you allow any area to dry aluminum oxide starts to appear immediately.
3.) Using a new paint brush, wet the entire surface with diluted
ALODINE 1001 from Aircraft Spruce. Rinse all alodine off and allow to air dry. *Do not dry with a rag or any fabric!* Small fibers will stick to the aluminum and become "wicks" when you paint causing the paint to fail.
4.) Apply a good chromate containing epoxy primer. I prefer Alexseal
Cor Spec Primer 135 | Alexseal Yacht Coatings
5.) Apply a good finish primer. I prefer Alexseal
Finish Primer 442 | Alexseal Yacht Coatings
6.) Paint it. This is the step that people think you are doing when you tell them you are painting your boat. In actuality you are doing steps 1 through 5 for 99% of the time.
