Thanks for all the kind words!
And to Jawge for his tutorial
http://traditionalarchery101.com/burlap.htmlThe fire hardening is pretty amazing. Endless thanks to Marc St. Louis for his research and writing on the subject. I would read his article in TBB IV if you haven't already.
This is the 4th time I've toasted a bow over a fire. The first time was hilarious. I just made a fire and held the bow over it like you would a marshmallow and within minutes I scorched the limb and curled it into 3" of set. Subsequent attempts have been much better executed. Now I cold clamp the bow to a wooden half-moon form with about 3" of reflex. I use 2 metal clamps, one on each tip so its light and easy to maneuver around the fire. I think its a good idea to rub the belly down with fat to protect the wood and I think it helps spread the heat out more evenly. I've used mink oil and bacon grease. I prefer the mink oil because it smells better and sometimes I like flavored bacon, like maple or honey chipotle, and it stains the wood a funny color (see pic).
The roasting is a skill all in itself. As you can see from the pictures, I'm still not getting a nice even roast up and down the limbs. The color comes on fairly quickly in the beginning when the coals are hottest, so I think keeping the bow moving at this stage would result in a more even roast. As the coals cool, I leave the bow propped up on cinder blocks, shifting it around every 5 or 10 minutes. My fire pit is only big enough to do one limb at a time, so I roast one limb, rekindle the fire, let it burn down to coals, then roast the other limb.
It seems like the real work is being done during the slow roast after the coals have cooled. The longer the bow is over the fire (without scorching), the better the results. The bow in the picture had a 1.5 hour burn time, but I think it would be worth trying a two or even three hour burn time as long as you can keep the wood from turning too dark.
After I pull the bow off the fire, I rub it down with turpentine/pine sap shellac and let it sit for a long time...days. Marc really harps on the sitting time in his article and I think he's right for doing so. The wood has to return to equilibrium moisture before you can work it, otherwise it will be brittle.
All of the bows I've heat treated had a backing glued on with Titebond III. At first, I put tin foil between the back of the bow and the form, thinking the glue would heat up and stick the bow to the form. This isn't necessary. The glue actually hardens and becomes what I refer to as Titebond IV. If you're planning on backing a bow, I would definitely do it
before heat treating. The benefits the heat has on the glue are astounding. The backing seems to cinch down onto the bow as it cools.
That's all I've learned about heat treating over a fire thus far. I'm still a beginner, so I'm speaking from limited experience and my methodologies are worth questioning. Maybe Marc could weigh in with tweaks/improvements in the process. He's the real expert in this realm.