I also just tried the Envirotex Lite Pour on Epoxy last night, and I left it on the fireplace mantle to cure, and after 12 hours it's soft cured (meaning you can't totally bend it but you can make a fingernail mark in it) By chance did you try to add a dye to it? That might have changed it's curing time.
Thanks! It's reached soft cure now, but I'm skeptical on whether or not it will fully cure. I can leave fingernail/toothpick impressions in it.
Could a humidity of 65% keep it from curing?
Also, one more question, is it true with Castin' Craft that it takes longer for thinner casts to dry than thicker casts? I always use a plastic cup to mix it in and then I keep the cup to see if the leftover in the bottom has dried before I mess with my pieces. Lately I've been coating instead of casting. The resin in the cup is, uh, rock hard, while the thin layer on my pieces is only soft cured. It's been about 60 hours.