Epoxy primer/sealer question

[gsauto63]

When do you use epoxy primer/sealer? Is it to be used only over bare metal? Or can it be used over an old paint job that has been sanded?

I'm working on a 91 ford mustang drag car. It's a stock steel body drag car. The old paint had bumps all over it. Like bubbles under the paint. I sanded it smooth then epoxy primered it. Probably a big mistake and it was too cold for the epoxy to dry and I base coated it. Yes, I screwed up.

So, how should I have done it? Right now I'm sanding it down to the factory primer (metal in some places). Should it all be bare metal? I see now going through the old top coat that those "Bubbles" were actually places where the paint was coming off!

Thanks for your help in advance! I'm just getting started in auto body painting and I want to do it right.

I was going to a tech school here but, it was next to the high school and most of the students were High schoolers, the class was more of a high school shop class than adult education! It was a waste of time! I'm 42 and have a wife and kids to take care of. I was getting taught more by the students than the instructor!

 

['68 Coronet R/T]

Since the paint on the car already had issues I would suggest it be stripped to bare metal. The epoxy applied over the bare metal will give you a solid, long lasting foundation for your paint job. Just be sure to follow the tech sheet and not apply it to cold metal or in temperatures under those required for it to cure.