Should I sand down to 100 or 150?
Should I wipe down with denatured alcohol or acetone?
How many oz for a 9’-5" longboard per side?
Leave it really rough, sand only with 60
Air off only
30oz resin.
[img_assist|nid=1041167|title=glossy|desc=|link=none|align=left|width=640|height=480]poly over epoxy
& does not chip off
word off warning polyester resin
will not go anywere near uncured epoxy
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try a sample first and be careful. I was playing with a test of Fiberglass Hawaii epoxy, and Fiberglass Hawaii Suncure resin. They appeared to mate, until I gave it a little flex, it popped right off. I’ve also tried the same on a board a while back. Looked good until a little impact. Resin immediately seperated and began peeling away from the area.
I was thinking it might work better if the epoxy first coat was with 2 oz cloth. Then the resin coat could be applied with a layer of 2 oz. That way each layer would be reinforced, while keeping the weight to normal.
I second the rough surface, 60 is best 80 will work. I’ve repaired many poly glosscoats that started peeling off LB’s and SUP’s. Many of the glassing shops these came from sanded 120-180. I do 80 on my personal boards (with a Festool dual motion sander) and never had any flake off. Do the rails by hand with that coarse grit.
I’ll weigh in with support for Huies statement.
Cured epoxy is one of the most critical things.
And by cured, it means really cured. Post-cured (best) or left in a warm place to cure for several days. Longer the better.
Otherwise you will have problems. Period.
Put it this way, epoxy is basically an inert hard surfadce when cured properly. You could eat your dinner off it.
But not 100% cured, and that poly will not cure well, will not stick, and do all the bad things you guys have mentioned.
If the epoxy is cured, then poly will stick to it as well as poly would to any hard, inert surface.
Keying up the surface is just basic common sense, but it also serves the purpose of removing blush and anything else that might get in the way.
It doesn’t matter how well you sand it though, if the epoxy is not cured FULLY, you are screwed.
So mix your resin right, cure it well, wash it off, sand it up, and poly is a walk in the park.