George, I cook osage until it gets a nice chocolate brown. It doesn't necessarily have to be a smooth solid color all the way down the limb either. I've used this method on the last few osage bows I've made. I generally heat treat when I'm adjusting the reflex near the completion of the bow.
On the tradGang Trade Bow(osage)I built last year I heated and straightened or heated and bent that thing so much that I think it got heat treated that way.
On a locust Eastern Woodland bow I'm working on now I heat treated the limb to a dark brown. I have given it over a week before I stressed it. I strung it last night and checked tiller and the pull. I'll still have to tweek the tiller some but it picked up a few pounds in the process. I don't know how much because I haven't checked the weight on it yet.
I'm also working on a hazelnut stave and I added reflex and toasted the belly while doing that. That wood doesn't seem to scroch very well. I'm sure it stiffened the limbs a bit and hope it will hold some of the reflex but I was surprised how little color I could get it to take.
From reading Marc St Louis' method my method shouldn't be effective...but it is for what I want. I can usually treat a limb in the time Marc leaves the heat gun on one spot. I'm gonna try Marc's method sometime to see the difference. When I heat treat I hold the nozzle of the heat gun about 1" above the wood and work in a 4" to 6" area at a time. When it gets to the color I want I move on to the next area slowly incorperating the heat into the new area while slowly taking it away from the last. When I finished with the whole limb I will start at one end and reheat the entire limb then let it cool at least over night before unclamping it. I'll wait a week or so this time of year because of the dryness and 3 or 4 days in the more humid summer before stressing the bow.
It is all still experimental for me right now. I'm still seeing what I can get away with.
