SOP for epoxy in a volume -- I've melted many a cup with leftover epoxy. Good advice here -- here's another tip that will keep the heat down when filling a hole, especially ar bigger one as needed when closing up a thruhull for example. Fiberglass tends to not like temps above 200 degrees, so... Take a plastic cup, pour mixed epoxy into the bottom, let it kick and harden, then pop it out. It should come right out, but you could give it a squirt of release wax if you want. Then clean the disk -- for either the amine blush or the wax -- and rough it up a bit with some sand paper for tooth. Put a layer of mixed epoxy in the hole, put the disk in, and add the rest of the epoxy. That way you reduce the amount of unkicked epoxy in the hole, and also the volume is spread out so the heat will be turned down.