The Stovebolt Site Forums The Shop Area Paint and Body Shop bare metal while block sanding

I have epoxy primer on the bare metal, then ppg shop line 2k primer. I was trying not to hit bare metal while sanding but did in a couple of spots. Can I put another coat of 2k filler primer and keep blocking? Is the 2k filler going to stick to that bare metal spot? The tech sheet makes it sound like it will, but I just want to make sure its not going to peal up. https://buyat.ppg.com/refinishProdu...tID=3a83823d-5ffd-4728-ad92-c2d667f354f8

Sorry for all the questions. new at all this painting stuff. Just want to make sure I'm doing it right.

I'm not a pro by any means but in my opinion you want a layer of epoxy primer under all of your paint and filler primer. So if you go to bare metal, I recommend that you go back over those bare spots with epoxy primer. The add more of the 2k primer. Joe

So is it ok to spray epoxy primer over 2k filler primer? Because I can't really hit a bare metal spot about the size of a dime without coating some filler primer.

If the spots are small, no bigger than a nickel, I'd just go ahead and paint it. It's not going to come off or anything like that. If you don't believe it just spray some paint on a clean piece of glass and see how well it sticks.

However, if the sanded through areas are large it probably means that the surrounding area is low and needs filler or you didn't use enough primer, but only you can make that determination.

Points to consider:

Epoxy primer is best over bare metal because it is not porous and therefore will prevent rust. It should be used if you want a protective coating over bare metal for an extended period of time. There is no other real legitimate reason to use it unless you want to make a chemistry project out of painting your vehicle.

High Fill primer is perfectly fine over bare metal as long as you protect the vehicle from rain. It can also be applied over any material that will not react with it as long as that surface is sanded and since it fills sanding scratches you can scuff the surface with 80-grit for an aggressive tooth.

Surface preparation and block sanding is a skilled and highly respected craft that is perfected over years of practice, but the novice can also produce an excellent finish with today's technology and an understanding of block sanding which is another subject far beyond the scope of this response.

I talked to the person at the PPG store today, and she stated close to the same thing. She said the the filler primer is just fine over metal as long as it is in a spot that I'm not too worried about rusting. Thanks. And you're right about the blocking being a skilled art. I'm starting to want to pull my hair out every time I see that I still have a slight low spot. But I'm getting the hang of it.

When I last got PPG certified in 2007, PPG said no bigger then a quarter. Any bigger and you should spray a light coat of epoxy. As for spraying epoxy over filler primer, yes its fine, epoxy can go on top of about everything other then etch primer...Eric