From what I've tried, a torch, alcohol misting ( like from a spray bottle) or even better, a heat gun, works amazingly, I don't have a heat gun, so I use a hair dryer on high for a couple of minutes and give it a rest because sometimes hair dryers like to reset the outlets in my house. But if you have access to a heat gun, and you do it outside, it works better than and is safer that the torch/ mini flamethrower. But if you're doing small resin castings, a mini torch whole be alright to use, but it doesn't always get rid of the air bubbles.