Just a follow up question, but it relates a bit more to block sanding...

These are my steps FYI:
Bare Metal
Epoxy
Filler
Epoxy
High build primer


Earlier in the thread I have done my first round of blocking with 180. I applied the putty in all the problem spots and applied another 3 coats of 2k.
I decided to cut them down again with 180 just to be sure all the body work was straight. All looks pretty good with very minimal breakthroughs to bare metal.

I'm going to do the car in a solid colour COB, so I want to finish sand in 600.

- Can I apply another 3 coats of the primer (its a high build and surfacer), and just wet sand it with 600 when i'm ready?
or
- Can I apply another 3 coats of the primer, wet sand with 320/400 and then spray a reduced coat of epoxy and when it goes into the paint booth (whenever that may be), just wet sand it with 600?

Thanks

If you have been using a good size sanding block and everything looks straight to you, I would shoot 2 more coats of primer.
Apply a guide coat and then block sand with 320 just to remove the guide coat.
At this point if the car is going to the booth shortly you can wet sand wet sand with 600 and be ready to prep and paint.
If you know it will be a few days before painting then shoot your epoxy sealer over the 320 grit and when ready to paint you wet sand with 600 first.

Thanks Coronet

It was my understanding that if you wet sand 600 grit epoxy sealer prior to base, you need to put another fresh coat of the sealer prior to applying the base - or is that not necessary because the first dry/ dust coat of basecoat will aid in adhesion?

Depends on the length of time between applying the sealer and getting to the booth.
If you end up outside the re-coat window of the epoxy then it would be advisable to shoot a fresh coat of reduced epoxy to reactivate.

Last week I sprayed four coats of high build 2K urethane primer on the right side of my truck and block sanded it with 320. I only had a few very shallow low spots, and I decided to use polyester glazing compound instead of hitting those areas with additional primer. Sand in 20 minutes versus 3 hours. Because the glazing compound was more difficult to sand than the primer, I wound up taking off too much primer in order to sand out the glazing compound. I caused myself a lot more work. In retrospect, I wish I had just sprayed a couple more coats to the dozen little low spots and blocked it out again.

When I do the left side, I'll do the latter and see how it goes.

I know deeper low spots should be filled with glazing compound instead of primer, but I'm talking about low spots that you couldn't really feel, only see with the aid of the guide coat.