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.
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.
In response to your previous post
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.
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.
