Thanks for the quick advice! The batch size is about the same, I did some yesterday and some today. I got more cracking today. I'm doing them in my garage, yesterday was about 75 degrees, this morning was cooler, maybe 65 degrees. I don't use any fans. The metal tins cracked more than glass. Should I have a heat source to keep them warmer as they are curing? How about if I put them together into a box to hold the heat. Would that work? Dale