1 part epoxy primer and more primer..
OK, there are many ways to do this, but I think most experienced body and paint guys (which I consider myself to be) would say that bare metal has GOT to be protected. 2K Epoxy primer is DTM (direct to metal), so it can be sprayed on the bare metal. It will provide a great seal against moisture getting to the metal. Most other primers will absorb water and you could have a rust issue. Here is what I always do:
1. Strip car to bare metal.
2. Blow it off and clean it thoroughly (I use lacquer thinner followed by a wax and grease remover).
3. Tack rag the surfaces to be primed.
4. Spray 3 coats of 2K Epoxy Primer (one light coat, 2 medium wet coats). Follow manufacturers time between coats.
5. Lightly block sand with dry 320 grit on a Dura Block (or similar). Every epoxy primer I have ever used has a slight natural shine, so compared to the scuffed areas, the shinier low spots really stick out. I guess you could use guide coat, but I never have. Then mark all the areas that need filler work.
6. Scuff the areas that need filler wit dry 80 or 120 grit paper
7. Do your filler work and follow up with glazing putty if needed. Don't use cheap filler if possible. Hard to beat Evercoat Rage Gold.
8. When I am done with all filler work, I lightly block everything with dry 320 grit on a Dura Block (or similar). again. This helps flatten everything out and feathers the edges of the filler a bit more.
9. CLEAN everything off, tack rag and then spray your favorite high build primer (mine is Evercoat G2 hands down).
10. Apply guide coat and Block sand with dry 220 followed by dry 320 grit on a Dura Block (or similar).
Mark all low places (you'll still see guide coat there) and fix them with glazing putty.
11. Prime with high build again and guide coat / block sand with 220 / 320 again. If all spots are looking good, I then sand with dry 400 (by that I mean a 400 meant to be used dry. Not the wet or dry 400), then wet sand with 320 and 400 wet sandpaper. If I am spraying metallic paint, I'll wet sand with 600 also.
When block and wet sanding, I never use a circular motion.
It sounds like you have put on a lot of primer, but you will actually wind up sanding most of it off. All my opinion, but I can crank out some nice paint work.
OK, there are many ways to do this, but I think most experienced body and paint guys (which I consider myself to be) would say that bare metal has GOT to be protected. 2K Epoxy primer is DTM (direct to metal), so it can be sprayed on the bare metal. It will provide a great seal against moisture getting to the metal. Most other primers will absorb water and you could have a rust issue. Here is what I always do:
1. Strip car to bare metal.
2. Blow it off and clean it thoroughly (I use lacquer thinner followed by a wax and grease remover).
3. Tack rag the surfaces to be primed.
4. Spray 3 coats of 2K Epoxy Primer (one light coat, 2 medium wet coats). Follow manufacturers time between coats.
5. Lightly block sand with dry 320 grit on a Dura Block (or similar). Every epoxy primer I have ever used has a slight natural shine, so compared to the scuffed areas, the shinier low spots really stick out. I guess you could use guide coat, but I never have. Then mark all the areas that need filler work.
6. Scuff the areas that need filler wit dry 80 or 120 grit paper
7. Do your filler work and follow up with glazing putty if needed. Don't use cheap filler if possible. Hard to beat Evercoat Rage Gold.
8. When I am done with all filler work, I lightly block everything with dry 320 grit on a Dura Block (or similar). again. This helps flatten everything out and feathers the edges of the filler a bit more.
9. CLEAN everything off, tack rag and then spray your favorite high build primer (mine is Evercoat G2 hands down).
10. Apply guide coat and Block sand with dry 220 followed by dry 320 grit on a Dura Block (or similar).
Mark all low places (you'll still see guide coat there) and fix them with glazing putty.
11. Prime with high build again and guide coat / block sand with 220 / 320 again. If all spots are looking good, I then sand with dry 400 (by that I mean a 400 meant to be used dry. Not the wet or dry 400), then wet sand with 320 and 400 wet sandpaper. If I am spraying metallic paint, I'll wet sand with 600 also.
When block and wet sanding, I never use a circular motion.
It sounds like you have put on a lot of primer, but you will actually wind up sanding most of it off. All my opinion, but I can crank out some nice paint work.