Osage and Dry heat? Revisited

[bentstick54]

I’ve been using dry heat to make corrections on some Osage bows after floor tillering. Depending on how much correction is needed I get some drying checks on the back of the limbs. I haven’t had a breakage problem because the all have run with the grain, but would like to minimize the checking. For those of you that use oil when using dry heat, is one oil better than another, and how much do you use? Do you just rub a little on the belly, or really saturate it? Does the oil “cook” or evaporate out during the heating process? How long do you wait after cooling do you wait to start tillering?

[Pappy]

I just use regular cooking oil, just rub on belly, not real heavy. It mostly cooks away, I like to give it a day if I heated it much, some don’t and say cool is cool. Another thought with your checks, if the wood is not seasoned and still a little wet it can do that also. Pappy

[bentstick54]

Thanks Pappy. I roughed out a stave the other day that I had split in 2013 and stored in my basement the entire time. Average year around controlled temperature runs around 66 to 68 degrees, 35% to 50% relative humidity. After working to almost floor tiller stage I let it sit for another month before floor tillering. I put in some slight reflex evening up both limbs, taking some minor twist out of 1 limb at the same time. I kept heat gun about 4 inches away and used a medium/hot temperature, and did about 4 inches at a time clamping as I went.

[Pat B]

If you seal the back first it will minimize the checking. I keep a can of spray shellac on my work bench just for this purpose. Any time I expose a fresh back, no matter how well seasoned I seal the back with shellac.

[bentstick54]

Thanks Pat. I haven’t sealed the backs once I got to this stage, but never had a problem with any that I did not try to heat correct any imperfections. I will sure give that a try on one that’s waiting for me to get to work on.

[superdav95]

I just use regular cooking oil, just rub on belly, not real heavy. It mostly cooks away, I like to give it a day if I heated it much, some don’t and say cool is cool. Another thought with your checks, if the wood is not seasoned and still a little wet it can do that also. Pappy

I do the same for minor corrections and such.  Canola oil works for me.  To get any excess oil left behind afterwards I wipe with a cloth after heating up the area then quickly wiping as the oils surface.  Best of luck.   

[PEARL DRUMS]

I use zero oil and never have even tried it. The only time I get any checks is when the wood isn't dry enough. When its dry enough you can pour the heat to it and have zero side effects, like checks opening due to moisture expansion. 

[Selfbowman]

I use zero oil and never have even tried it. The only time I get any checks is when the wood isn't dry enough. When its dry enough you can pour the heat to it and have zero side effects, like checks opening due to moisture expansion.
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This x2 . That’s s scary pearl. You and me thinking alike.🤠🤠

[bentstick54]

Chris and Arvin. Are the backs of your staves sealed before you put any heat to them?

[George Tsoukalas]

Yes, sir. Checks mean stave is not dry. I agree with PD and Arvin.

[PEARL DRUMS]

 

Chris and Arvin. Are the backs of your staves sealed before you put any heat to them?

Nope, never do that either.

[Selfbowman]

Not sealed for me either.i will say this I was able to see and afford the need for a stave stash years ago. My wood could have  been cut 5 years ago if need be. And it gets dry in central Tx.

[Pat B]

I think the R/H of your area might have something to do with it. Because I've had a few osage backs check when heat treating I started spraying the back of any newly exposed stave with shellac and haven't had any check since. Some of these staves were 10 years in my basement shop before I used them. It's little enough effort and cost for me to continue the practice.

[bentstick54]

Thanks everyone. The stave was 10 years old when I removed bark and sapwood, chased the back ring, and then floor tillered. Then left at that stage for about 30 days. My humidistat? showed an average 33% and temperature held a steady 66. I guessed according to the charts the wood moisture should have been somewhere between 7% and 8%. I didn’t think that was too much for Osage, or am I missing something?

[Pat B]

I think 9% to 11% M/C is more acceptable for osage but I've never had one 7% to 8% M/C so it's only what I've read.