I did a third coat Glass Craft 3 on my first resin piece (800 x 400) last night and I checked it two hours later and was looking good - this morning it has several pits.

I did lots of preparation , I sanded it down to a flat smooth surface with a random orbital sander. I cleaned the surface many times , dried and blew it over with canned air. I washed it with acetone and made sure it was very dry. It was levelled out and pre heated before I did the pour. All the temps looked good and I made a cardboard box to cover it after the pour and I get this result. I am thinking that I have to change my brand of resin.

Simply can't carry on getting these results.