David do yourself a favor and pick up a thin metal pick from hobby lobby. Not sure what exactly they're used for perhaps sculpting, etc but I've picked up two of them from hobby lobby in the past. Heating and powdering your mold is all nice and good but sometimes some molds especially wheels with lug details will still hold a bubble that needs to be released. I use the metal pick for this purpose. Pour your resin, locate the bubble and "release" if from where its stuck with the tip of the pick. The purpose is not to pop the bubble but to release it from where its stuck. Now use the pick and slide the bubble away from the cavity of the 1 piece old. In addition, you'll need to stir your resin slower and more carefully trying to minimize introducing or causing bubbles to occur. This will also help. Lastly, place a flat piece of glass on top of your mold with a light coat of mold release. This will generally move those bubbles away that you freed up with the pick and give your resin piece a nice flat backing. After each use, just wipe the tip of the pick clean with paper towel. Works like a charm every time.