short version:
If you heat granulated epoxy resin, the granulation will disappear. It’s just like when honey crystallizes and is reheated. It will kick like normal.
Long version:
6 months after building my first board, I started a second one, intending to use the remainder of a gallon and a half of Resin Research epoxy. When I pulled the resin out of my closet, where it had remained at a constant 65 F - 71 degrees F, it seemed almost solid and no longer transparent. I squeezed the bottom of the jug and it seemed to loosen up a bit. I was concerned that it was no longer good. Having only spent $18 on the foam I built my new board with, I decided to go ahead and use it to glass the board with, win or lose since the upfront cost was small. I started by mixing it up some with a wooden paint stir-stick and it no longer seemed quite as solid as it initially did. I mixed up a batch and glassed the bottom of the board, some of the resin being still a bit grainy. It seemed to kick a little bit slower than I thought it should but I glassed both sides with less than ideal results. To speed up the hardening when I did the hot-coat, I placed a heater in my workspace, facing the board. I noticed where the heater was blowing on the board, the granulation was disappearing completely. I got out my heat gun and gently heated the rest of the board and, voila…it smoothed out like, well…glass. The first hot-coat seemed to harden perfectly. I’ll keep you posted on the end game with the opposing hot-coat.
I’m really disappointed that Resin Research makes no mention of granulation/crystallization of the epoxy resin or what to do about it. They say the shelf-life is at least 12 months and I guess this may be a storage issue and not a shelf-life issue per se.
I’m hoping some of you can indicate what storage conditions you keep resin at and if you’ve experienced granulation. I read a thread here on Swaylocks and the guy said he just threw out the resin assuming it was useless.