I like to use mar-glass over any welded seams. ( where quarter skins or such are welded or patches in the doors or fenders) I do a thin coat. Then I use rage gold over a repair(next step after mar-glass or on dent repairs) Then i use evercoat metal glaze to finish it off. If your do not use a good quality primer and notlet it dry properly. the repair will show thru. A good epoxy primer is a very durable choice. Oy use a good 2k primer

 

Rage extreme is supposed to be pinhole free but i would invest in some glaze just incase