Why does the resin have tiny bubbles as I'm mixing ?

You will see tiny bubbles as you mix any epoxy resin, that is part of the mixing process. Air bubbles are caused by oxygen that is whipped into the epoxy as you stir. Do not mix epoxy too quickly or rigorously; this will create additional air bubbles into the mixture before pouring.

After pouring your epoxy, most of the bubbles will disappear. Be sure to use a torch or heat gun to eliminate the rest of the bubbles on the surface. Use your heat device in an even and continuous motion to help remove most of the bubbles on the surface. This step is crucial because it not only levels the epoxy and releases small air bubbles, but it will also give it a glass-like look.