Rust-Oleum Self Etching Primer
I've been using Rust-Oleum Self Etching Primer during the empennage construction.
After final dimpling or deburring, any scratches created are sanded away with 400grit wet/dry sandpaper and then throughoutly cleaned with mineral spirits to remove dust, oil/grease, sharpie marks, hand marks, sweat, and vinyl adhesive leftovers.
Then a light coat of primer is sprayed, let to dry, part flipped over to a new layer, let to dry, part flipped over for the main/heavy layer, and repeated on the flip side.
Most parts are left to dry overnight before working again on them, and the more it dries, the more difficult it is to remove.
This has worked very well for me, no unnecessary use of air compressor, no paint mess, thus maintaining a clean work area and happy neighbors.
I guess a very important key before priming (with almost any primer to obtain overall good results) is preparing the parts to be primed: that is sanding and/or cleaning so the primer actually etches to the aluminum evenly.