A: There is no household product of which I'm aware that will adequately prepare aluminum for painting.  You can purchase a two-component wash primer from an industrial paint store (not a hardware store), but you will need to follow the instructions to the letter and you will need to use a spray gun.

 

If you are not concerned with adhesion or outdoor exposure, then you can abrade the aluminum to give it a somewhat rough texture, solvent wipe with isopropyl alcohol and as soon as the surface is completely dry apply the artists acrylic.

 

I cannot guarantee success, but at least this procedure will be better than nothing.