Has any of you done any fire hardening of wood so that it would last longer as the implement you designed it to be (shovel, knife, spear, hammer, boat paddle.)?

I understand it involves heating wood to just below the charring state and then scraping it down with a not too sharp scraper (steel, rock, bone). I am not sure, but I seem to recall reading that this procedure had to be done to the item several times, and such wood hardened to a point would supposedly penetrate wood of the same type deeper than if it was just sharpened and used without fire hardening.

As I recall, they recommended the use of hardwood for this procedure.

Have any of you ever tried it and is it worth the effort?

Bountyhunter