If you are having problems removing bubbles in resin, we recommend using a torch, not a hair dryer or heat gun. Even a small artist torch will not supply enough heat to efficiently pop bubbles. Here is the setup that we use and suggest for our artists:

torch for artists
This is an automatic lighting torch attachment.
It is just as important to choose the right gas to attach to your torch. Most bottles at the hardware store are made to produce high heat for soldering and braising- this isn’t ideal for resin. We recommend using propane because it produces a more controllable heat.