I agree that it is time and high heat. You can see and feel the difference in the wood when the heat treat is successful. Long stretches in temps ~150° don’t do what proper heat treating does. I suspect that the long fire hardening process folks are talking about just carries the cellular effects of a proper heat treat through the neutral plane and just under the back. This is what has me wanting to build a pipe burner oven. Would have more control over a more even temp than coals or even a heat gun. Be easier to maintain and set up than a coal bed. As long as the back of the bow was outside the top of the oven, then there shouldn’t be any damage there. If the fire hardening method folks are talking about still has advantages in water resistance, that has to be due to the creosote and such in the wood smoke, and that can be easily added with a burner setup.
