I'm building a Sassafras 16 from the kit (MAS Epoxy, slow hardener). I recently finished applying two coats of epoxy as a barrier coating and sanded the whole canoe down with 80 grit (Norton 3X sandpaper). I sanded through in a few areas, but in other areas I think there were still some small (1/8" diameter) glossy indentations left. I decided I should roll on a complete third coat to cover the bare areas and fill in the glossy indentations. I vacuumed and then wiped the hull down with water a couple days ago, then vacuumed again last night before rolling the coat on. It was fairly cool, maybe less than 60 deg F. About 15 minutes after I started I noticed some fisheyes beginning to form in the epoxy. I didn't realize what they were until I looked them up today, so at that point I didn't try to do anything about them.
The fisheyes are mostly 1/8" or less in diameter, although some of them are oblong and maybe a 1/4" long. They are only on the #1 and #2 strakes (the 2 on each side closest to the keel). The #3 through #5 strakes look fine.
Most of the stuff I've found about fish eyes says they are usually caused by some sort of contamination. I suppose that's certainly possible but I can't think of anything I used that would have contaminated the second epoxy coat. I realize now that I should have wiped the hull down with vinegar or laquer thinner to remove any contaminants, I'll definitely do this before applying any more coats.
I'm wondering if it's possible that the cooler temperature combined with the glossy indendations caused the epoxy to pull away. I wouldn't expect that to happen, especially since the articles I've read say you can recoat after a "light sanding."
What do you think? Can I scrub with vinegar and then apply a new coat over the coat with fish eyes, or do I need to sand the fish eye coat down to zero glossy indentations before applying another coat? Thanks for your help.