I use RAKA and put my gallon containers in a tub of hot water an hour before glasing. Then I change the water to a fresh batch of hot water. It's pretty thin then and has never gone off on me. I use the no-blush.

You can thin it a bit with acitone but only use a tiny amount like a quarter teaspoon (or less) to 4 oz. It will weaken the epoxy but not enough to notice or feel. If you add too much, you will actually get epoxy that won't harden to a rock hard stage but will harden like hard rubber.