Wouter’s on the right track, if weight is primary criteria and cosmetics don’t matter (or if you’re painting over), then there are many lightweight epoxy fairing compounds you might use. Or you can make your own. Added benefit is it sands super-easy.
If you’re certain it’s sealed, sand the lam (not deep ) with 80 grit and go over it with a poly glosscoat. Cut it with styrene and surfacing agent and put it on smooth enough to start sanding at 320. Take it to 400 and leave it a sand finish. No hotcoat gives any structural strength; if it isn’t in the lam it’s not there. How light do you really want it? The biggest weight savings is going to come from reducing the EPS density and using the thinnest cloth possible. Like any ultra-light competition board, these are designed to win not last.
I apply the sanding coat with a squeegee. Use fast hardener, cover the whole thing first then lightly pull the excess off with the squeegee as the epoxy starts to gell just a little bit. The squeegee just touches the top of the weave. Comes out nice and even with minimal sanding to do after that. I brushed on my first couple of boards but as you found also it seems to take a lot of resin.
Thanks Dawnpatrol. I was beginning to think I was nuts. I feel better now.
Last night I did the bottom.
I spread it with the squeegee, then quickly stroked with a brush. It didn’t end up as even as I would have liked. I may be in for some hard work sanding, but I think it took half the resin my last bottom required.
On the rails, I used just the brush.
Building these 14 footers is like building two 7 footers at once. Lots of sanding!