Do NOT use a heat gun! Hair dryer works great as it's a gentle heat. A heat gun will cook the oil/trichomes and ruin it. The use of an oven (kitchen or vac oven) works also. As long as your kitchen oven can be set to 170*. Not all kitchen ovens can go that low.
I've done LOTS of testing. Various bulbs, orientation of said bulbs, frequency of changing bulbs, etc. 15yrs or so or lots of fails, but lots of success also.