Any experiances regarding hickory selfbow loss of weight in a hotbox?

[shaun748]

I don't have a moisture meter, and live near the ocean, with about 60% humidity.

I figured I would play with the hotbox to see what I could get out of a hickory bow (hopefully without over drying it). I decided to go all out and keep the bow in the hotbox fulltime unless I was shooting it.

My rigged "hotbox-Pipe" runs about 105 degrees w/ 23% humidity(which if I calculated right would theoretically get wood to 4.9% MC )

I only had the total physical bow weight as my reference point and am wondering if my results mean anything to those with more wisdom?

before the hotbox I initially weighed the 68in NTN bow(w/leather grip,no string) at 1lb 11.2 ounces pulling around 52@25.

 

After several weeks it just barely lost an ounce. It is now 1lb 10.2 ounces and only increased weight to 54@25.

I know there is much more to this, but I am wondering if I basically got it about as far as it will go.  I don't know if that is a lot of weight loss or not, and since it took so long to lose that last ounce does it mean it is already stabilized pretty low??

I know this has many variable and no real answer, but hopefully someone has a better idea of what this might mean..

thanks

[Marc St Louis]

Is the bow sealed?

[shaun748]

Hey Marc,,It was sealed with a spar finish??(I did not build the bow so i'm unsure exactly)..

I just recently removed this finish during my recent experiment in trying to toast the belly and have since been sealing with grease .. I say I "attempted to toast the belly" kinda-tongue-in-cheek since I know you are very knowledgable in this regard and I must admit I did not use the better methods you would suggest(I just tried an open flame to see if there was any change).   

I now see what your getting at though, since that sealed finish would explain the slow change in weight..  Mabye now that I've removed the spar I'll see how fast any changes occur.

wow, all you had to do was ask me a question and I now see what I had completely overlooked..

Does one ounce of weight loss really equate to much change in MC in your experiance.  I was suprized I only gained 2 lbs of draw??

thanks for the help
 

[tom sawyer]

After several weeks, I would think even a sealed bow would equilibrate.  There's no such thing as a completely moisture-proof finish after all.

You lost 1oz of moisture, and are left with a 5% MC in your bow (presumably).  That means 5% of the 26.2 oz is moisture, thats 1.3 oz of moisture still in there.  This means the bow was originially around 9% MC, not an unusual MC although maybe a little higher than your RH would dictate.

My guess is that your bow is pretty well dried to its MC, but you can continue to weigh it and see if you lose more weight.  I'd reweigh once you strip off the finish to account for any slight mass change.

One more thing, when you dry wood past its normal MC for an area, it won't rehydrate all the way when you put it back.  It stays about 10% drier according to the Wood Handbook.  So even if you take the bow out of the hotbox, it might not gain back all the moisture.  I think this is one of the things that contributes to the effectiveness of belly toasting.

Edited to add:  the way to tell if the bow is equilibrated, is to continue to weigh it daily and when it weighs the same for a week, then its probably to its final MC.

[Badger]

I have actualy found the best cross section I can come up with for performance is a cross between the elb and the flatbow, the outside 1/2 of the limbs an oval cross section and the inside half near the center of the bow a flatbow. Steve

[shaun748]

Thanks for all the replies everyone..

Tom,, ,, you pretty much exactly answered my questions about this,,that was exactly what I wanted to know..  I did not know that it won't rehydrate as much..very interesting..

Thanks..