First, thanks to Bill, Etienne, John, Kudzu, pawistic (got the E-mail, thank you) for replies on my questions about thickened epoxy, old epoxy for end pour, and microballoons. My thick-mixed combing epoxy hardened up, and a subsequent test batch made a strong join of scrap wood.

Then, I tested my old epoxy to verify it was still good for an end pour. I mixed it with some microballoons for a test. Wow, you really have to get it thick to get enough bulk to gain desired lightness per volume -- sort of a chocolate pudding or icing mix.

AND FINALLY, the question: even in my test batch of a couple of ounces of epoxy with microballoons, it generated enough heat to deform a Solo cup as it just sat there. The end pours are supposed to be 8 ounces each. 8 ounces should be capable of generating a lot of heat. I know this is done all the time, but why doesn't it cause problems?