I bought the streaming version yesterday and watched it. Clewis, when you log on to your account page, you will see a green bar across the top of the web page that says "watch the video" or something to that effect, with an arrow that points to the right. Click that arrow, and you will be taken to a page where you can stream the vid. I thought that was a peculiar way to set things up. Not at all intuitive.
As far as the video goes, fire hardening, as they portray it, does seem to differ from heat treating as it is commonly done. I would think of them on a continuum, with using raw, unheated wood at one extreme and fire hardening at the other, with conventional heat treating somewhere in the middle. The basic idea is you create a bed of coals you can suspend the bow you want to fire harden over, and suspend the bow there (clamped to a form if desired, with the belly facing the coals) for a few hours. Obviously the wood is further from the heat source than if one were to heat treat with a heat gun. The length of time you leave the bow there depends on a range of variables, among them how much heat the coals are putting off, wind, air temperature and humidity, etc. The goal is to 'cook' the wood at a relatively low temperature (~270 degrees Fahrenheit) slowly for an extended period of time.
It seems that a consequence of fire hardening is that the physical/chemical changes that happen in the wood go deeper than with heat treating, and in some cases all the way through, from belly to back. Fire hardening does result in a color change, but not as much as many folks end up with who heat treat. The bow becomes much more resistant to taking on moisture, and supposedly retains its performance when at higher moisture contents than it would otherwise. The producers claim only marginal benefits for osage, and significant benefits for white woods, particularly hickory.
My main criticism of the video is that when the producers presented data comparing the FPS that fire-hardened bows achieved vs raw wood bows and a couple fiberglass bows, they compared bows with various draw weights at various draw lengths using a single 520 grain arrow, so the comparisons were not always useful. Looking at their setup, it was not at all clear to me that they had a method to prevent them from over- or under-drawing bows while testing, which adds a means for them to bias results in favor of fire-hardened bows by 'accidentally' overdrawing them while shooting through the chronograph. With those limitations in mind it is hard to say much about the FPS numbers they present.
In my opinion, the producers are definitely onto something useful, and while there is plenty of room for more investigation I think their original claim that fire hardening is meaningfully different from heat treating, as it is commonly done, is valid. I plan on finding a place where I can make a fire pit (cannot do it where I am currently living) and experiment with this once it warms up a bit.
