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My apologies up front… but time for Tony to show his ignorance again… RE: “Cooking Wood” / I have questions…

It has been said “ …this is not is not a substitute for allowing woods to dry and stabilize.”
But isn’t that exactly what we are doing when we “cook” the wood?

It was also said – “The primary purpose is to fully shrink the wood so that when / if it is exposed at a future date to an extreme that it will suffer less from the experience. After a point the wood will permenantly / semi-permenantly remain "shrunk" and this will help the top weather extremes. I think this is the primary reason the factories do it.”

…which - in my simple way of thinking, I agree those who say – “…making it more stable, at least for a while.” Or, in other words – “…don't call it baked wood, but stabilized wood.”

And it was also said – “It's not about tone, setting pitch, or anything else. It's about bringing the wood down to its minimum possible dimension, then letting it come back up to its proper moisture content. Done correctly, the wood is much less likely to split and crack if expeosded to an ectreme dry situation later. It also shows any possible weakness, wind shake, etc..., in the top BEFORE you build with it. It also will reveal any hidden pitch pocket(s) before you go further. It does not affect tone!

And it was suggested that “We can artificially age materials by holding them at higher temperatures.”   But - that “…is not 100% reliable.”

Now, I’ve read where we need to allow newly aquired wood to acclaimate to its new home before building with it. I think I can appreciate the logic behind that practice. That process is more about stabilizing the wood than anything else – right? My question is – how will the process of “stickering” the wood for years affect the wood any differently than “cooking” to bring the moisture level close to 0 and allowing it to come back to the ambient conditions? I realize that “cooking” alone will not replicate the affects of the sum of weather conditions that the wood would be exposed to if left “…in a stickered pile in the attic of my unheated garage” for years. But if “cooking” only stablizes the wood in one extreme – then why not also flash freeze it while your at it? (joking – so laugh for me now - thanks)

And if “…there really is no substitute for thoroughly seasoned wood” – what quantifies the difference between “seasoned wood” and “stable wood”?

I guess the real question I’m asking is: If I buy wood to build with – can I just “cook” it – stack it – and in a few weeks – build? Or what? I don’t want to buy a stock pile of tops – and wait years to begin building. What’s a poor boy to do?

Thanks for your indulgence.

Personally, I hold on to most wood for quite a while before I build with it regardless of the source... (of course there is always the occassional "emergency" or "opportunity", but more often than not... a year is the minimum for anything).

I define dry as the amount of moisture in the wood, and stable as allowing the wood to equalize in a way that if you are going to have problems with internal stresses (cup, twist, bow, etc.) it shows itself long before you build with it. When I get wood it immediately goes into the sticker pile (dry or not) for a few months... and sometimes a lot longer depending what I am into, then I move it to the shelf and stack it.

(just to give you a for instance the tops I am considering baking were cut in '94 and hit my woodpile in 2000). So for 6+ years I know they have been at 40 - 45% RH.)

Baking drives the top to an extreme shrinking it severely and (as the theory goes) it never quite returns to its original dimensions. This conditions the top against extremes and helps prevent future problems. I know many others who have written in depth articles on this. You should find them and read them. The case is well explained and convincing.

Beyond that.... the theories about how it helps improve the quality of the sound are just that... theories. However, I am one that firmly believes in the qualitative side of what we do. Sometimes we "know" things work long before we know "why" they work. Not to say this is, or isn't a contributing factor to the sound but enough prominent builders seem to think it is that it is worth further exploration.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

[QUOTE] Baking drives the top to an extreme shrinking........[/QUOTE] Does it really?
Heat causes items to expand.
Sorry, I'm just asking if anyone really knows or if this is an assumption.
OK - next time someone bakes, could you measure the wood before, during and after baking? Then report your finding here. I think it would be most interesting to measure across the grain, but with the grain might be interesting also. I think if we mark the locations that we measure it will add to the reliability of the data.

BTW - The expansion or contraction will probably be small, I don't think the difference will be detectable with a ruler. You'll need calipers or a setup with a dial indicator.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Does it really? Heat causes items to expand

Not everything. Water expands when cooled to the point of freezing....

But back to wood. Wood is hygroscopic. It takes in or releases moisture to maintian itself at equilibrium with its environment. Moisture makes wood swell, and lack of allows it to shrink, no matter the temperature. Heat reduces the environmental RH, thus forcing moisture from the wood, thus shrinking it. Reduce wood to zero moisture, and you've reduced the wood to its most minimum possible dimension. Soak wood until it can absorb not a drop more, and it has swollen to its largest possible dimension.

The ancient people would often quarry stone by drying wood to zero moisture content in ovens or by laying timbers in desert sands, then driving these timbers into cravaces in mountains, and they would then pour water on the timbers. The wood's expansion upon re-gaining its moisture is so unrelenting and powerful it would split massive stones.

None of what we are doing needs new data. It's all been known for thousands and thousands of years. Kids, this ain't new news, fercryinoutloud....

[QUOTE=Hesh1956]

I think that someone did do some measurements and indicated so in the original thread and observed what that Seinfeild episode was about where George experienced shrinkage.......[/QUOTE]

Hesh, I think that water was cold!

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Joe Breault
Merrimack, NH
Perpetual novice

I usually try to inject a bit of humor in the things I say – without being silly. If I fail at either – go easy on me – I’m a newbie.

Whether cooking improves the “tonal” quality of the wood or not - for me right now - is not an issue I want to tackle. However, I certainly would like to know if someone thinks it would make the tone worse (and why). I haven’t heard any warnings to that affect.

So, the question really becomes - what benefit is gained? Based on what I have read - I sense that there is a real benefit in helping the wood to become more stable. I do understand that removing moisture will cause things to “shrink” – even though heat will cause things to expand.

Brock – you said, “I define dry as the amount of moisture in the wood, and stable as allowing the wood to equalize in a way that if you are going to have problems with internal stresses (cup, twist, bow, etc.) it shows itself long before you build with it.”

I recognize that a process designed to remove the moisture content in a piece of wood and then allows moisture to be re-introduced – can serve 2 purposes: Discover how the wood will react to being forced to one extreme and allow that process to relieve stress and stablize the material if it doesn’t fail. And I see cooking the wood as a process that that will do both.

I work in an industry where some of the materials that are used will require stress relief using extreme heat. The process of heating the material to those extremes will allow torquing forces that have been built into the assembly to be released – rather than allow it to to tear stuff up later - if they are left un-treated.   Same but different. So, I understand and agree with your definitions.

So, what does years of storage before building add into the wood that doesn’t get discovered and or conditioned into the wood after cooking.

[QUOTE=tony] I usually try to inject a bit of humor in the things I say – without being silly. If I fail at either – go easy on me – I’m a newbie.

Whether cooking improves the “tonal” quality of the wood or not - for me right now - is not an issue I want to tackle. However, I certainly would like to know if someone thinks it would make the tone worse (and why). I haven’t heard any warnings to that affect.

So, the question really becomes - what benefit is gained? Based on what I have read - I sense that there is a real benefit in helping the wood to become more stable. I do understand that removing moisture will cause things to “shrink” – even though heat will cause things to expand.

Brock – you said, “I define dry as the amount of moisture in the wood, and stable as allowing the wood to equalize in a way that if you are going to have problems with internal stresses (cup, twist, bow, etc.) it shows itself long before you build with it.”

I recognize that a process designed to remove the moisture content in a piece of wood and then allows moisture to be re-introduced – can serve 2 purposes: Discover how the wood will react to being forced to one extreme and allow that process to relieve stress and stablize the material if it doesn’t fail. And I see cooking the wood as a process that that will do both.

I work in an industry where some of the materials that are used will require stress relief using extreme heat. The process of heating the material to those extremes will allow torquing forces that have been built into the assembly to be released – rather than allow it to to tear stuff up later - if they are left un-treated.   Same but different. So, I understand and agree with your definitions.

So, what does years of storage before building add into the wood that doesn’t get discovered and or conditioned into the wood after cooking.
[/QUOTE]


I think there continues to be a serious misconception that the baking process' aim is to dry the wood. It is not. My wood is plenty dry to work with. I maintain a very stable envionrment at 40% - 45%. So the wood is plenty dry. The moisture content is not what is what stabilizes the wood. The wood stablizes on its own. Some wood just goes a little nuts when it comes out of the stickers dry or not (I notice this particularly with Black Walnut). Sometimes the internal stresses cause cups, twists, bows, etc. independant of the moisture. If this is going to happen I want to know about it before I build with it.

The baking process is not a substitute for proper handling of the wood. That is not the point of it.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

My take right now is that some folks get it, some don't. Those who don't, won't, no matter how we explain it.

That shows a lack of basic wood understanding, from a crowd I would have thought understood wood very well. May I suggest, honestly, that many of you need to put away the luthier tools and store bought jigs, and spend the enxt couple/few months studying wood, woodworking, and the old techniques of woodworking. Your instruments, and all you do going forward, will be the better.

I now believe too many here have skipped "wood 101" and went straight to "instrument making". That is like trying to grasp algebra before understand addition. Sure, we now have calculators and computers to do the bulk of the math for us, but if we can't understand the WHY, how can we understand the answer?

I state the above with all due respects, and in all honesty. Many of you need to go back to the basics.

[QUOTE=Mario] Does it really? Heat causes items to expand

Not everything. Water expands when cooled to the point of freezing...
[/QUOTE]


Water expands with heat just like most other things.
When cooled, water contracts just like most things, until it hits 4 degrees Celsius, then it begins expanding again because the molecules assume a different configuration in the solid form.

Ron

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OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

[QUOTE=old man] [QUOTE=Mario] Does it really? Heat causes items to expand

Not everything. Water expands when cooled to the point of freezing...
[/QUOTE]


Water expands with heat just like most other things.
When cooled, water contracts just like most things, until it hits 4 degrees Celsius, then it begins expanding again because the molecules assume a different configuration in the solid form.

Ron[/QUOTE]

I don't get the point. That's exactly what Mario said, but 4C is only 39F and water doesn't freeze in my frige so molecular change hasn't happened yet. As usual I'm probably missing the obvious

i have to admit,, i am one of the skeptics... not that this idea works, but as to why... Lets face it well seasoned wood kept ina controlled room at 40-50% rh will get to about 6% moisture. Thats really low, and yep, by heating it up you could get it close to 0% and "shrink it" so much that its cells are puckered up. But As it has been stated many times here it will return to 6-8% when it is returned to normal room conditions.. so what really is going on here....go back to the original post and read Kevin Gallagers post regarding crystalization/curing of resins. If this was all about removing all the moisture it could be done with out heat.. Maybe not easily by you or me, but it can de done with dehumidification.. Or desecants. But the heat does more then dry it, it causes the resin to cure which in turn inhibits rapid absorbsion or release of moisture from the cells of the wood. Therefore stabilizing it.. Do I think its a good idea,,, heck yeh,, if people can tell me they have no instability issues since starting this practice it must be worth a try. I just think moisture content has little to no effect on this, its all heat related.. Ask the next indian you see why he puts hot pine resin on the outside of his wooden canoe.
When resin is cooked and cooled it becomes almost waterproof.    Of course all the walnut I have been working with lately could be effecting my judgment too.    
Mike
By the way,, i think this has been a great thread, with a lot learned by many.. Hopefully it will remain very friendly.

my interest is not woodworking or wood, it is guitar making. And although the two are very entwined my woodworking knowledge has gone from nothing to something simply by building a few guitars. What is wrong with that?

Nothing's inherently "wrong" with it. But you would honestly better yourself by learning more about wood, its properties, and what history has taught us. We all would. I spend nearly as much time perusing woodworking forums as i do here, though I don't post at all there. My post was more directed at the skeptics who question direct experience(not just mine) and perhaps hundreds of centuries of passed down knowledge.

A set of spruce that has been at 40% RH for 4 years(or 24 years, for that matter) is at 6% MC. Great. It has stabilized there, and remained there. Great. But by forcing it down to zero moisture, it will shrink and upon climbing back to 6%MC, it will NOT re-gain it full dimensions. It is now "pre-shrunk", if you will. Have none of you ever seen a top crack that wouldn't close back up, no matter how much moisture you exposed the damaged guitar to? Any guesses as to what happened? Re-read the previous sentence. Ever see a piece of old furniture with an open crack or split in the veneer? Same deal. It likely lived in a breezy old home heated with wood, where the RH dips to single digits every winter,and remains there for months. Go ahead and sponge it wet; it won't close back up. For the same reason.

Put a dent into some fresh spruce. Now, steam it out. Go ahead, let's see if it all comes back. Sometimes it will, but at a certain point, it won't. It will never re;gain it's original dimension. Sound familiar? When cells compress to a certain point, they won't come back.

I love sharing information; it's why I hang out here. I learn from y'all, therefor, I give back. But dang, it gets long in the tooth having to argue to "prove" ourselves all the time to the few who wish to argue what they don't understand.

Sometimes it's just the mater of the wheel going round and round a couple more times for some people and untill the "click" happens, they just don't get it. The writen word can be hard to comprehend sometimes, and than throw in the structure of some material be it wood, steel, plastic and we all get fubar'ed some times.

Thanks for all the knowledge that you share Mario, I personally have learned more from you in the past 5 years than I probably have from any one other person on any of the guitar forums (I know you don't like emoticons, that's why it's in there [bg])

It must be getting colder up in your neck of the woods, your starting to get a tad bit grumpier [bg] (I'm joking of course)

I sure like this topic, it's a realy mind bender of sorts, and I sure have learned a lot about stabilizing wood. Thanks to everyone who has shared.

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"There's really no wrong way, as long as the results are what's desired." Charles Fox

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I don't think that Mario is suggesting that we drop what were doing and take up wood studies as our second career. I think we could all benefit from reading a book or two, however. Understanding Wood by Bruce Hoadly (sp?) is supposed to be quite good. It could easily be read while waiting for finish to dry or sides to cool.

I love Shopnotes magazine and that woodwork forum in Aussie land, great resources to the non-initiated!

From the "for what it is worth category" I took my last set of top plates and ran them through the jointer BEFORE cooking them....mind you the joint was perfect. So I take a peek at the set after the cooking sessions and low and behold the joint is not even close to matching, that wood moved a fair amount. I would guess that it shrunk, but I did not measure before and after, so I'll leave it up to you to determine what happened.

Greg

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Gwaltney Guitars

First off. Brock – Mario, I do seriously appreciate your willingness to engage me on this topic. I am sorry if my “newbie-ness” aggravates you – but that’s just TOUGH!!! <bg> I’m just the type person that will continue to push until he gets things squared and plumb in his head. Expect that from me. Thanks in advance. I pray for your patience, and that your patience will be rewarded!

Paradox. “The moisture content is not what is what stabilizes the wood.” And yet -“Wood is hygroscopic. It takes in or releases moisture to maintain itself at equilibrium with its environment.”

“I think there continues to be a serious misconception that the baking process' aim is to dry the wood. It is not.”   And at the same – we would all agree that the baking process does dry the wood – and that drying the wood will cause the wood to shrink in size dimensionally – so that 0% MC = smallest dimension (generally speaking). When it is forced to shrink, if there is not enough elasticity in the wood, it will fail (assuming it is elasticity that keeps it from splitting). Right? Not from heat, but from lack of moisture causing the wood to shrink. Forcing the wood to 0% MC with heat will reveal its ability to withstand an extreme shrinkage – and (according to what I have read) will condition the wood in a way that will help prevent future failures.

Other wise men have said: “ The effects of temp and humidity changes can be limited to a certain extent by cooking tops. The dimensional changes that occur when the relative humidity changes and the tops begin to either absorb or release moisture are determined by the top's ability or inability to do so.

By cooking the tops, the ability that they have to absorb moisture is affected since resins or pitch is set or as some have siad, crystalized through hardening by the heat and cell structure is solidified beyond what natural time sesoning will cause.”

And another wise man said: “Hemicellulose is the part of the wood that adsorbs and desorbs moisture from the air, so as it dissappears the wood becomes more stable. The density also drops, as does the stiffness, but the density goes down faster. Very old wood that has lost a lot of hemicellulose becomes opaque, owing to the spaces, sort of like a snow bank.

I think that baking the wood cooks off most of the loose ends, so to speak, of the hemicellulose, making it more stable, at least for a while. Whether the effect is permanent is hard to say, at least based on the little I know about it.”

I don’t believe anything I have said so far disagrees with any of these statements. And I don’t consider any of these points in contention.

Call me dense - but IMHO, my question has not really been addressed yet. The topic is “seasoned vs stabilized”. There is another affect of applying heat that I am calling into question.

Let me come at it again from another angle. (next post) Patience now. <bg>   Thanks again.

Brock pointed to the issue I’m hoping to learn how to understand when he said – “Some wood just goes a little nuts when it comes out of the stickers dry or not (I notice this particularly with Black Walnut). Sometimes the internal stresses cause cups, twists, bows, etc. independant of the moisture. If this is going to happen I want to know about it before I build with it.”

And this newbie said earlier – “I work in an industry where some of the materials that are used will require stress relief using extreme heat. The process of heating the material to those extremes will allow torquing forces that have been built into the assembly to be released – rather than allow it to tear stuff up later - if they are left un-treated.”

And I went on to say - “Same but different.” …meaning I understood that these two processes are similar in some ways, but can’t be said to be the same in all ways.

IMnewbieO – heat does more than just reduce moisture content. We heat sides to bend them – and once bent they become stable in their new un-natural state. And – IMO- heat only accelerates a process that could be done without heat. It might take months – perhaps even years, but wouldn’t it possible to bend those sides – incrementally over time and without heat – and get the same results?

This is the question. Can heat be used to help relieve the built in stresses that might be in natural wood, by using heat – and perhaps even stickering the wood during the cooking process – to re-cast the wood into an un-natural state (if necessary) to prevent it from going “nuts” later on? In other words – using heat to bend it straight? <bg>

Simply put – could we use heat – not only to temper the wood somewhat against the adverse effects of RH and temperature changes, but also to accelerate the seasoning of the wood – making it stable by relieving the natural stresses that might be present.

The caveat to all of this would be the point made by one of these wise men, when he identified the possibility that this whole thing might make “…it more stable, at least for a while. Whether the effect is permanent is hard to say “. But perhaps it would be long enough to allow natural seasoning process to catch up.

Am I making any sense – at all?   Let me ask the question again: What does storing wood for years (seasoning) before building a wooden instrument impart to the wood that wouldn’t get discovered and or conditioned through the process of cooking the wood (stabilizing)? The only thing I’m seeing right now is the potential that the immediate benefits of cooking may only produce a temporary state that only time can really adequately work permanently. Good logical argument, but would that be true? Science or opinion? And if scientifically true wouldn’t time eventually catch up with the temporary fix? Or would the temporary fix prevent time from working her magic?

Don’t you just love “newbie” questions?

[QUOTE=GregG] From the "for what it is worth category" I took my last set of top plates and ran them through the jointer BEFORE cooking them....mind you the joint was perfect. So I take a peek at the set after the cooking sessions and low and behold the joint is not even close to matching, that wood moved a fair amount. I would guess that it shrunk, but I did not measure before and after, so I'll leave it up to you to determine what happened.

Greg[/QUOTE]

Thanks Greg. Curiousity. I would assume that you had also thicknessed the tops before cooking them. Did the process deform the plates on the surface too?

Since the subject of this discussion is the conversion & seasoning of wood there is a book by that title.

Somewere along the road I heard the myth of the fiddle maker that buried his tops in clean white sand for a period of time?

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Actually I never thickness them (final thickness)before cooking them because it seems there is always some resin which finds it's way to the surface....running the tops through the sander removes any trace of this resin, that's why I wait....sending this set through the jointer before cooking was just a boo-boo, interesting results though. And NO I've never noticed any odd thing happening to the tops along their surface, I do use some sticks to secure the ends, but even when I've not used anything but the wood itself in the cooker, they never move much....no cupping is what I'm getting at.

Greg

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