Do I strip the primer off?

On resin ship hulls, I will fix the gross spots first, then prime.   Any small spots which the primer reveals are then fixed and  they are then spot-primed.   A light sanding - or even a buff with an old t-shirt  - will level & blend the two primers.

It depends on the adhesion of the primer—hopefully anything you use for a primer will have great adhesion. In that case, just fix the defect, sand, and spot prime. If you are  using automotive body compounds like Acryl Blue, they bond well to just about anything that has a clean surface. Same with CA, but it may lift acrylic primers. In that case, I lightly sand the spot, repair, and spot prime.

 

Thanks to all for responding.  I'm using the Testor's grey primer over resin.  After it let it set for a while, that's when I noticed several scratches and pin holes that I missed.  I was thinking of using some Mr. Surfacer 500 on the air bubbles but I wasn't sure if it was okay for me to use it right over the primer or if I should sand off the primer first or if I sure use thinner to strip off the primer in the trouble area and then use the Mr. Surfacer.

I'm not using any automotive body compounds, just the Testor's primer.  Then I was going to use Testor's Model Master enamels over that for the top coats.

Thanks,

Eric