another body work q..

ok lets say i have a ding or a spot that i shaved..well i take it to bare metal and feather out the old paint then i put filler over the bare metal.. but when i sand im going to have a few spots were the filler did not cover or whent away when i sanded that exposes bare metal..what i do i put some selfetching primer over those spots or the filler primer by it self.also wont bare metal rust under the body filler

i use a DTM urethane hi build primer. no need for that. as long as you dont use spray can youll be fine.

as long as bare metal is covered with anything it won't rust... i've never had problems with rust coming through and i've never used selfetching primer

Body filler is made to adhere to metal. After that u can use a high build primer and I've seen people use a good sealer primer to lock in the body work once its finished.

etching primer isnt really for rust epoxy primer is etch is so your surfacer can stick primer doesnt have good adehsion to bare metal unless it has a acid base.