Did you try baking it to set it? The directions say you can put it in the oven for 1 hour at 150 and that's what I did. They looked beautiful going in, but when they came out they were cloudy and full of bubbles!
I guess from now on I will have to just let them sit overnight. It was perfect before I put them in the oven, no bubbles at all! Oh well... I hate wasting bottlecaps (especially when I don't have many!