[fred56]

I shot a 2 part epoxy primer on the firewall of my Model A coupe and after it dried I found imperfections under the primer.

My question is can I just scuff the surface and apply filler(bondo) over the bad area or do I have to take all the epoxy off and starft from square 1.

Thanks - Jerry

[Lizer]

It's actually best to put filler on AFTER epoxy! Barry will say you don't need to sand or scuff if it's within the 7 day recoat window but I still do lightly with 220.

[deadbodyman]

X2,same here

[tech69]

if it's adhesion issues then take it down to metal. It all depends on the damage. In a perfect world I'd do some rough metal work BEFORE epoxy then finalize it. In a normal world I block it, determine what needs to be pulled up with stud pins or dolly's and what can be simply filled. I like to sand my epoxy with 80-180 grit after blocking cause I'm not secure with filler edges that don't properly feather out, which is a true sign of bad adhesion. My opinion hinges on whether or not the epoxy was applied thick enough to do that. If you get it epoxied at a blasting company that sucks it will be thin, sucky adhesion, and I'd rather just take it off. If it's epoxied in house and there's a tad to block out AND get in some good scratches then that's what I do.

[Elevinpointsixtoone]

I'm not a paint expert but because of that I read the data sheet that comes with the product. It should tell you exactly what you can and cannot do with their product including filler. If you don't have the sheet just plugin the primer product descrip/number on google and the data sheet should be right there as a PDF. At least this is true with PPG product.