After cleaning/de-rusting, I've shot rattle can flat clear on bolt heads to keep the rust from developing again but maintaining the natural look. Mostly for very visible bolt/screw heads.
Chip
'Rusto-Mod' '51 Chevy 3600 5 window | C4 Corvette front/rear suspension & drivetrain | everything else looks old and stock '92 GMC Sonoma GT #15 of 806 '91 GMC Sonoma GT Extended cab 1 of 1 Trucks, Trucks.....and more Trucks |