As described here in text form:
or in video form:
Youtube commenters seem to have a hard time accepting that this will ever work. But Matthias' main points are:
1) it's quick and painless, so you can wax more often, which is ultimately better
2) don't leave negative comments without trying it first.
So I tried it. It worked just fine.
I used the rubbing + heat gun technique on a new pair of Dynastar Chams and skied them for two days in the French Alps. The wax job was fine, it even looks like I got better penetration than with a traditional iron.
To make things more scientific I've prepared a pair of skis where one ski is waxed with an iron using conventional wisdom, and the other ski is waxed with the heat gun. I've re-waxed my Chams half-and-half, the tip of one ski and the tail of the other using the heat gun. I'll report back in a few weeks on those.
Not only did I get good glide, I actually liked the heat gun better as a tool.
1) I can SEE what I'm doing. I can see the wax melt and the base open up. The action isn't hidden under the sole of a hot iron where I'm always afraid I skimped out on wax and hot air pockets are sealing/burning my base.
2) I can modulate the heat better. I can move the gun closer to the base near edges or bindings or anything that draws heat away. I can point the gun at the edges, sidewall or even the topsheet if I feel the need to do so. Jacques has a neat video about this, to do a good job waxing, you need to warm up the entire ski. It looked as if the heat gun did a better job at that, just by feeling the temperature of the top sheet with my hand.
The 'patch' the heat gun is shooting hot air at is approximately 3cm by 3cm for my gun, I find that to be a more convenient size than the footprint of an iron. For work near edges or aluminum tip protectors anyway.
BTW a heat gun is also useful when your local ski shop has messed up a base grind and ptex hairs are sticking up everywhere. You brush so the hairs are pointing up, then hit them with the heat gun. If you get it right, their tips will melt first and they'll turn into little dandelion-like structures. The heads give a scraper something to grab onto to pull them off. It's somewhat dangerous though, the ski is unwaxed at that point.