Primitive Archer
Main Discussion Area => Bows => Topic started by: Weylin on June 14, 2009, 11:21:42 pm
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Im finally ready to heat treat my bow. I have done my homework and gathered my tools. The only thing that im unsure of is, what, if anything I need to use to rub or brush on as I heat it. The article in TBB4 suggests several oils and varnishes none of which I have. Is it imperative to use something or do people heat treat without. Do things like olive oil or canola oil work or are they a bad idea. If it matters, I have a Hickory stave flat bow. Let me know what you guys think.
Thanks,
Weylin
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I think olive or canola oil will be just fine. Its just to keep the wood from scorching and help distribute the heat a bit.
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I have heat treated a few bows without the varnish or oils and had good results. I think it is much safer and better with though.
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Are you heating the wood to correct a problem or are you heat treating(tempering) the belly to add compression strength? These are 2 different animals altogether.
When I correct problems in a stave, ie. crooks and bends or adding recurves, I use oil on the wood to keep from scorching and I believe it helps distribute the heat evenly and hold the heat longer.
When tempering the belly I use no oils because I want to scorch the belly to solidify the oils and resins in the belly wood thus increasing the compression strengths. Once this is done however you should not stress the bow at all until the wood has had time to rehydrate. This could take a week if the humidity is low. Also, don't temper the back as it will make it brittle and prone to breaking.
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yup just like patb said
and olive oil smells real good on hickory,so does crisco ;D
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So you guys use no oils or protection for the backs?
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i dont apply direct heat to the back so why grease it
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I have always heard the heat can reflect off your forms and damage the back unless it was protected. But like I said before I have done it a few times and had no problems so it's probaby fine.
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Weylin, there is no need for oil or grease if you are tempering the belly.
I use leather shims to help protect the back from heat reflecting off the form.
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Thanks everyone for your input. I went ahead and treated it tonight and I brushed a little olive oil on behind me as I went. Sorry Gordon, I didnt see your suggestion until I was finished, I hope it wont hurt anything. Everything seemed to go just fine, it is holding the reflex that I added. I know that I am supposed to wait for the bow to reach MC equilibrium before I start flexing it again. It is a hickory bow in Portland with a relative humidity of 70-80%. How long should I wait?
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If your form is wider than the bow then the heat will bounce off it and scorch the back. Wait a couple days at that RH
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What Marc said. And don't worry about the oil, it won't hurt a thing.
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Thanks Marc and thank you for the great heat treating article in TBB4, that was indispensable.
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I thined my form down to less than the width of the bow all the way out to the tip.Ronnie
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Gordon was gracious enough to lend me his caul. Only the last 8 or so inches of the tips were narrower than the form so hopefully there wasnt to much damage to the back.
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There were some oils which I did not care to use when heat treating, linseed oil being one of them. Tung oil on the other hand produce good results but my favorite is sap from any of the conifers. This I thin down a bit with turpentine. I do nothing to the back including applying oil
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The saga continues. During the tempering process I had used a caul to flip the tips and induce some reflex and it worked fine. I have since started working the bow after giving it a couple of days to regain its moisture. It feels massively stronger and Im unable to string it at this point so I have started taking some wood off the limbs evenly to reduce the weight. I have been gently exercising the bow with a long string as I remove wood and I have noticed a potential problem. one of the limbs is retaining the majority of its reflex and the other limb is nearly straight again. because the bow has gained so much strength from the tempering I havent been able to get a good feel for the state of the tiller. It was well tillered before I started the process but given that I am inexperienced it is hard for me to judge it with the new reflex especially since one limb has alot of reflex and the other doesnt. I know that one should expect to lose a fair percentage of reflex gained from tempering but Im not sure how to interpret or deal with the imbalance. Any thoughts?