I have a question regarding primer. I have a door panel that I repaired and numerous small stone chips in my paint.

I stripped the door down to bare metal and covered w/etching primer and several light coats of Krylon primer.

Any stone chips that where down to the metal where also covered with etching primer and coats of Krylon primer.

This is my first attempt at body work and the job turned out great.
BUT - I've read two things that concern me.

1. Certain Primers are not waterproof
2. There are sometimes incompatibilities between primers and paints.

I'm concerned that I'll end up doing all this work and end up with issues after I have the truck painted.

Should I just cover the current primer with a coat of PPG or SEM primer that is water proof or do I need to strip off all of the current primer and start over?

Thanks

 

Your paint job will only be as strong as your weakest link. Only you can decide if what you have put down, will serve as a good starting point.

The paint job on my truck is several years old. I stripped the paint to bare metal and did my filler work on the bare metal. Then I sprayed rattle can lacquer primer over the filler work. Being a work-in-project, I continued to drive and work on the body over a several month period. Not knowing any better at the time, I didn't realize the primer wasn't waterproof.

About a week before it was painted, I noted a small rust stain in some of the primer. When I started sanding, I discovered the entire side of the pickup bed had rust growing beneath the primer. That small rust stain was just the tip of the iceberg. I ended up having to redo the entire side.

What was strange was that I had worked the entire pickup. Only one panel had developed rust. On a positive note, the urethane paint job is still as sound as the day it was sprayed although the base is rattle can lacquer.

Your paint compatibility issues can resolved by having a sealer applied before the final paint job. I use epoxy primer as a sealer. It protects the old paint from the new paint.

If I was you
Since you used a self-etch, you probably have a firm attachment to the metal. Assuming I knew the panel had not been exposed to moist conditions, I would probably just apply a sealer and paint it.

 

Thank you.