Originally Posted by Cotemar
Rubbing alcohol will take the epoxy right off the gelcoat.
Has worked for me many times.
The epoxy can says to:
Clean resin or mixed epoxy residue with lacquer thinner, acetone or alcohol.
Yeah but only while wet/uncured.
I replaced a rotten lazzerette bulkhead in our boat with a epoxied, glass-wrapped marine-ply panel, which I then proceeded to glass- and over-epoxy into place, as only an amateur can. And of course I touched the boat every time i crawled in/out of the lazz, and dripped in various and sundry places.
The only way to remove the cured spots was by carefully sanding
them off. Masking around the epoxy blotches helps preserve the surrounding gelcoat. Finish off with wet-sanding and compounding. It wasn't too hard, and the spots are completely gone.
Handy tip - the spots are easier to sand off if you let the sun hit them for a year or two.
(ok, I was slow to get around to it)