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Heat treating demystified (Somewhat)

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PatM:
I think it was already explained in layman's terms by Marc. What you have done is misrepresented the process in layman's terms.

lostarrow:
Just a little extra info for those interrested in the "why" behind the "how" PatM. If you feel the info is incorrect , please feel free to present a rebuttal. I believe this is a discussion forum for the advancement of "Bowyery"and in the spirit of such  ,discussion is a good thing.NOWHERE were there any statements, attacking or contradicting the findings of Marc.On the contrary I posted the info in the belief that a slightly more in depth look at the subject would further promote  the benefits of this technique! A question presented by another member ,in another post prompted me to write it to give a possible conclusion to the failure of his bow. In doing so, I realised this info may have been of interrest to others. Please take the time to read all of the posts here again and let me know where I've offended you, so I can assure you it was unintentional. At the risk of reiteration , I found Marc's conclusions to be well founded and completely supported by the scientific knowledge we have gained over the last century regarding cell structure of wood and how it responds to heat.
--- Quote ---Please , if anyone finds anything I post to be in error, feel free to quote the statement and present your argument for the contrary. I'm only human and am not offended by being proven wrong. Humbled perhaps, but not offended. When we stop learning , we die.


--- End quote ---
In response to your previous post
--- Quote ---lostarrow, The shrinkage and decreased moisture uptake of the heat treated wood still doesn't explain things. A heat treated bow can at least be brought back to an intolerably high mc for a regular bow and still perform better. You may not be able to turn a raisin back into a grape but a moist heat treated bow performs better than a bone dry regular bow.
 I'm not sure if anyone has dried a stave for 7 years in forced reflex and compared it to a bow heat treated into reflex though.
--- End quote ---
The shrinkage of the heat treated cells cause the  hollow portion of the cell that holds the water to decrease in size, while the solid portion of the cell walls(lignin,cellulose ,minerals etc. ) contain the same amount of material(very slight amount may be lost ,but not enough to be concerned with for our purposes),thereby creating a more dense structure.  As we know , a higher density is a desirable for the belly of a bow as long as the back can tolerate the extra strain. The higher density and the Crystallization of the "sugars " (several chemicals exist in wood and form hundreds of compounds that research has only scratched the surface on ,so for us  it is the sugar that helps the tree grow.)slow the transmission of moisture into the heat treated area. The back , having not been "toasted " will allow the transmission more readily.Extra moisture in this area is more desirable as it keeps the wood more flexible. In this way we are  changing the ratio  for the characteristics of any given wood. A wood already good in tension but not so much in compression, comparatively, will now act like a wood with a higher compression to tension ratio. A moist, heat treated bow CAN outperform a bone dry  regular bow all dependant on the ratio.To understand moisture content  and how it is measured ,scientifically compared to in the field might greatly help understand as well. Scientifically , you cook a sample of wood until it stops losing weight  and calculate the difference based on what it weighed at the beginning . In the field it is measured by placing electrodes into the wood and comparing the electrical conductivity to the known conductivity of water. (close enough for the purposes of most people dealing with wood) The non-probe method uses the same principal  only with magnetic fields as opposed direct electrical connection. The big problem with these is that they would have to take into account the variable mineral and chemical compounds within the would to be accurate. The $400  ones attempt to take this into account but there are a huge amount of variables to look at depending on  where a species grows. A Cedar tree growing in a swamp filled with iron is going to have a different composition than one growing in a fertilized garden.Iron conducts electricity differently than "Miracle Grow" . (HAHA)They are an indicator only and should not be relied on %100. As you said yourself heat changes wood like no amount of drying.That was never a question.  As wood shrinks ,it will never again be able to hold the same amount of water it did before.It can still absorb water ,just not as much and at a different rate.As for the seven year drying ,that would refer to the extra stabilization a piece of wood has after going through the moisture loss/gain cycle seven times compared to one. Having said that, if improperly stored ,(excessively dry) ,that piece could be worthless for bows because  it could have lost enough moisture to break the bond between the cells. I've dealt with one and two hundred year old hardwood that was like a piece of sponge toffee(furniture restoration days).

I try to read these posts over after I've written them to see if they make sense ,but it made perfect sense to me the first time I wrote it at 1am. I may be taking some things for common knowledge and not getting the point across as intended but keep questioning, that's the only way to advance. Thanks.

TBod:
About the 2% weight loss right after heat treatment:

Say that you lower the MC (moisture quota would be a better name) from 10% to 0 % on the belly and maybe a couple of mm inside. How big a portion of the bows total volume is that? Maybe a 1/5. Then 1/5 x 10% = 2% water or weight loss.

Then it regains some water so the MC is maybe 6% on the belly. 10-6 =4 x 1/5 = 0,8 % total weight loss.

Just an example how to value the weight loss. (Sorry if I am no good at explaining)

I really appreciate your work and patience lostarrow, keep going!

crooketarrow:
  IT'S PERTY MUCH MY THINGING ALSO.
 PERSONALLY I DON'T heat threat my personal bows. But for 2 reasons I do once in a while.
 (1) When your building someone a bow to MOST people when the think bows the see a straight limbed glass bow.
  (2) For the last 15 years. I have reflex and untwist as soon as I cut my staves. Then its do natural NO HEAT NO CELL DAMAGE.
Then you can build the bow as staight as you want in most casts. If I do use any heat it's in the handle area to help line up the tips.

  UNFORTENTLY I CUT 100'S OF STAVES WHEN I STARTED 21 YEARS AGO. AND DID'N T KNOW ABOUT REFLEXING THE NATURAL WAY. Some of these I have to heat for some people. If they really don't understand self bows, like I said the exspect a staight limbe bow.

  What I see on here ALOT is the wrong use of the kind of heat used on the wrong wood. THEY'LL SAY I'VE ALWAYS DID IT LIKE THAT. IT WORKS FOR ME AND IT MIGHT WORK. FOR A WHILE BUT YOUR NOT GETTING ALL YOUR BOW AS TO OFFER.
 Heating kinda like getting set or string follow. Once the damage none or you change wood cells it's none and you can't go back. And you can't build the bow to it full protental.

   I do beleive if it not done right (IT CAN'T BE IN THE REAL SINCE) or if it's none at all in most woods. The bows not what it could be and the bows life with excessive shots would'nt last as long as it should. FOR THE ADVERAGE PERSON WHO ONLY SHOOT A FEW ARROWS EVERY COUPLE DAY OR LONGER IT USWLLY WON'T MATTER.
  Were not talking bending the tips or the handle. Heats won't hurt your bow heating a none working part. I DO THIS, I'LL BEND A HANDLE AREA TO LINE UP THE TIPS IT I NEED TO. BUT LIKE I SAID ON PERSONAL BOWS I NEVER HEAT A WORKING PART.
  I'd say OSAGE TAKES HEATING FAR BETTER THAT ANY WOOD i KNOW OF. The risins and oils help to stop the wood for srinking the wood cell like said.
  They heat up and you don't have to heat the wood near as much as others. Meaning you do'nt get the koisture loss as you do from heating other woods.

   Your right people do get real defencive. When heats wood comes up. I think its just because your telling them differnt ,went they've been doing it their way all along. Changes not bad. I've built over 100 bows but don't think my ways the only way. It suits the ways I do it.
 IF I READ A POST THAT I CAN USE TO MY BENIFIT I CHAGNE RIGHT AWAY AND TRY IT ON THE NEXT BOW. BUT FOR A LOT OF PEOPLE YOUR HURTING THERE WAYS OF THINKING AND THE WAY THEY LEARNED.
  EXSECIALLY ON THE NO BAINER THINGS.
  VERY GOOD AND WELL WRITEN POST.

PatM:
I'm not sure why you guys are getting upset that a poorly written, sweeping generalization post might be critiqued a bit.
 It is quite easy to see how the post can be misinterpreted as making a reference to heat treating just being "super permanent drying".
 I wasn't aware that so many people were struggling with the process so if you think that first post is a lesson in how to heat treat properly, then that's fine.
 The last post goes into a bit of the detail as to what goes on in heat treated wood and we ignorant buffoons can understand the slightly more complex lingo of the non layman's terms. ;)

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