Polyester Primers

AdamR said

So do you only use it for the first round of blocking ? After you 2K what do you block that with and how many times will you re-prime and block.

When I did my Dart I only used 2K, I used 180 till i was pretty much dead straight, Re-primed and went 320, Then re-primed and went 400 wet, and 600 wet.

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Regardless of the type of filler primer used I always used 180 to board sand. The faster you take a product off like filler or even primer the more straight the area will become. If you use too fine a grit all the board or block does is ride the humps. You need something that cuts. Then prime with a good 2k primer like PPG NCP primer to fill the sand scratch. I find that people tend to finish sand with too fine of a grit. 600 wouldn't be bad but some people suggest 800-1000 which is not a good thing. You are using mechanical adhesion from this point on and I usually finish with 400. You can actually get away with 320 orbital (not the best way to finish primer) or 400 straight. As long as you are using a good sealer like epoxy.