A question has come up this week regarding whether you should apply filler first and then epoxy or vice versa. Every body shop has its own way of doing things so I did some research, to see if I could set matters straight. Please read the following and then you be the judge. Autobody filler is (basically) made of a vinyl ester or a polyester type resin. Epoxy primer is (basically) made of an epoxy type resin.
If you were to bond/glass over a metal pad to a fiberglass boat,