: This is a good reason to keep the seal coat thin. If you can get the glass
: coat on while the resin is still green you can avoid sanding all together.
: If you don't sand the surface may be a little rough and tend to catch the
: glass a bit, but it is not a problem if you work with care. If you get
: drips you will want to wait several days so the resin can set up hard and
: permit sanding/scraping.

Thin, even and methodical application seems to be the rule.
I've built a couple boats so I thought I had this pre-coat process down. I have a hull where I applied the sealer coat quickly, ran down one side and then, when I started the other side, found a few spots where the epoxy had dripped over onto the dry side. No big deal, right? After all, I was going to seal that side with a thin even coat shortly, just like the first side. I figured I had plenty of time using Clear Coat. I quickly finished but the places with the drips had already absorbed more epoxy. No amount of coaxing evened out the color and the dark runs remain visible after glassing and a couple fill coats. I had assumed that the wood would absorb whatever it was going to absorb in the end, up to whenever it started to gel. I could have sanded the whole mess off but I thought the additional coats putting on glass and filling would even it out but didn't happen.