Hi James,
I'll take a stab at it. Although I've gone through the same things that you've described, I am by no means an expert. It takes a lot of practice working with epoxy to be able to do a perfect coat. What I like to do is to use a long handled scraper to remove the worst drips etc., but this is best done on the second day, while the epoxy is still somewhat green. I think the scraper works better, because it only removes those high spots and not the surrounding area. You are correct, however, that you can sand all you want to, as long as you don't sand through the glass cloth. In fact, the more scraping, sanding, smoothing that you do now will make the subsequent fill coats much smoother and less sanding later. As for sandpaper, you could use a rougher grit (50/60) to remove the ugly drips, but for most (if not all) of the epoxy sanding you should stick with 80, 100 or 120 grit. You shouldn't need anything smoother until you get ready to varnish (at least to 220 if not 400). And yes, when you apply the next coat of either epoxy or when you varnish the micro scratches from the sandpaper (or the haze) will disappear.

So to summarize, don't worry about it, you just have some sanding to do. If you have a very thin coat over the glass cloth, just sand it with 100 or 120 so that you can see how close you're getting to the cloth. Keep in mind that you really don't want to breath this kind of dust (take it outside if you can). If, while you're sanding, you see the white texture of the cloth, stop sanding that area. That too will disappear on the next coat. When you've completed the epoxy sanding and fill coats, sand the final product down to as smooth as humanly possible. The varnish won't fill in low spots etc... But it does hide the sanding haze you're concerned about. Keep in mind the window of opportunity to get a good chemical bond between epoxy coats (usually recoat within 12-24 hours).

Yet another ROS recommendation: Sanding at slow speed with an ROS on semi-hardened epoxy won't gum the paper nearly as bad as a regular single speed palm sander. Change paper often.

Good luck. Keep us posted.
Smf

: Can I sand out drips and thickness changes of the epoxy with a rough grit
: before final sanding? On the sides some drips formed as I didn’t have the
: time to stand around for hours redistributing the resin with a squegee
: while it cured. Some spots still had weave showing, so I put another coat
: on to fill, but the transition in epoxy thickness is obvious as the
: viscosity is too high to smooth the transition of a new application into
: an old one. I’m under the impression that I can sand however I want as
: long as I don’t go through into the mesh and that I start with rough and
: work my way up to fine sandpaper. I started to attempt the fix by adding
: more epoxy, since the sections where it cured smooth looked great. The
: only problem is that I would have to do the entire boat this way to avoid
: new transitions, and that would use too much material and add too much
: weight. One of my concerns is the haze you get from sanding: I imagine
: that the varnish will wet it out and it will disappear. I’m hoping that
: the solution to the haze isn’t more resin, since that puts me right back
: to where I started. Any suggestions on technique, sanpaper grits or any
: advise is appreciated.