What temperature are you working at or storing the epoxy? When I glass, I always bring my epoxy up from the basement to get warm the day before. I also put my gallons in a bucket of very hot water before I use them. I actually shake up my epoxy mixtures in tomato sauce jars and still don't get air bubble problems. If your epoxy is thin, you will not make bubbles and will less likely entrap any that get released. Sounds like you were working in a decreasing temperature setting, so you are entrapping bubbles with your application. Try heating the epoxy to lower the viscosity and your bubble problem will be gone.