I've had my GP epoxy and T-88 Sytem Three epoxy start to crystalize and it's due to being stored in the cold and not using it for long periods of time. Move it to a location where the temp is above 70 and it's less likely to happen.

I have a microwave five feet from my building table that iI usesometimes to heat upvery small amounts ofepoxy resin (2 to 4 grams) for making repairs.No more than 8 seconds on highandI now have a laminatingresin that wetsout extremely well. I just lay out somefiberglass over therepair area and pour it on then use a tinning brush to spreadout the resin. It will set quite fast if it's too hot. Maybe 85 to 95 degrees at most.

I also use my heat gun to warm up the epoxy as once the temp falls below 70 degrees F it thickens up quite abit.