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Cooking wood
http://www-.luthiersforum.com/forum/viewtopic.php?f=10102&t=8747		 Page 1 of 4
Author:  Brock Poling [ Sun Oct 08, 2006 7:13 am ]
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I am going to start baking my tops, but I need to bake them full sized (due to my method of thinning them). They don't fit in my oven (we have 2 small ovens rather than one regular size one.)

I was thinking of building a box with a series of light bulbs under it heating a metal bottom, and wiring up some sort of thermostat... but I was curious if anyone had a better idea.
Author:  A Peebels [ Sun Oct 08, 2006 7:21 am ]
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What You are describing is what construction workers refer to as a hot box. Every big job around here has a few, used to warm their lunches, and they work great. In fact you sometimes have to throttle them back by using smaller bulbs to keep them from getting too hot. Be sure to use porcelain bases for the bulbs, and start with small bulbs then work up to get the temperature that you want.

AlA Peebels38998.6826273148
Author:  Dave-SKG [ Sun Oct 08, 2006 7:42 am ]
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"better idea"...go to your local Pizzeria and have them "bake" the tops for you. There are times of the early day that they are warming their ovens and don't have pizzas in them. Didn't you ever see Kramer do the same thing on Seinfeld?

Hey and while your there...get a Calzone to go!


Another idea... go buy a used oven ( or get one for free from some contractor who's remoldeling)and install it in an appropriate sized box with insulation. During those cold winters it can help heat the shop and the rest of the time you have a fairly inexpensive "TOP COOKER" Dave-SKG38998.6984143518
Author:  Pwoolson [ Sun Oct 08, 2006 8:23 am ]
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Brock, better be careful of the center seam. Most glues and heat don't get along too well. If I'm remembering correctly, you are using HHG which shouldn't be an issue. But for the builders using Tightbond, I think it's a bad practice.
Author:  GregG [ Sun Oct 08, 2006 8:35 am ]
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Seems like you should cook the tops before joining them, is there a reason why this wouldn't work?

Greg
Author:  Don Williams [ Sun Oct 08, 2006 8:46 am ]
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I would cook the wood before jointing it and thinning. The desired effect of baking will still work with the wood a little thicker, and you won't risk softening glue or epoxy etc.
Or is the truth that the Mrs. will kill you if you use her good ovens for baking wood.....?
Author:  Joe Beaver [ Sun Oct 08, 2006 8:49 am ]
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[QUOTE=Pwoolson] If I'm remembering correctly, you are using HHG which shouldn't be an issue. But for the builders using Tightbond, I think it's a bad practice. [/QUOTE]
I was thinking HHG turned loose around 140 degrees and Titebond around 190. I'm I wrong on that?
Author:  Mario [ Sun Oct 08, 2006 9:21 am ]
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Yup, you be wrong.
Author:  TRein [ Sun Oct 08, 2006 10:03 am ]
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Just because Taylor and Collings bake their tops does not make it a good idea. Why a small builder would want to take his/her soundboards to 0% moisture content is beyond me. I have an intuition as to why the "big guys" do it, but there really is no substitute for thoroughly seasoned wood, IMO. I put my soundboards in a stickered pile in the attic of my unheated garage. The wood goes from 10 degrees and 80% R.H. in January to 110 degrees and 30% R.H. in September. The movement of the wood or "seasoning" from season to season and from day to day is what it is all about. Oven dried wood has had all the moisture driven from its cell walls and as far as soundboards for acoustic instruments go, really is something new under the sun.
Author:  Brock Poling [ Sun Oct 08, 2006 10:56 am ]
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All of my wood is well seasoned (well, the stuff I am using is....). This is more about shrinking the wood severely, crystalizing any remaining resins(?), improving the stability, and ultimately the sound (but I recognize that is a bit subjective).

There is a lot of research to support the fact that this helps... I see no reason why you would not want to do it.

I will be joining these after I bake them.

Thanks for the suggestions guys...Brock Poling38998.8315046296
Author:  John Lewis [ Sun Oct 08, 2006 11:28 am ]
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Taylor and others bake their tops to help supposedly "season" them. It is supposed to help the tops withstand changes in temp and humidity. I'm not sure what I think of it yet.

I tried it with a fairly fresh-cut top that was air-dried to 6% RH in my home - it had been resawn 6 months prior. I placed each half of the Engelmann top in my oven (180 degrees F) for about 3 hours. They each came out with lots of dried sap or pitch on the surface that came up out of the wood. I had measured the weight and dimensions of each half before and immediately after. It did shrink a bit and weighed less. I immediately weighted and stickered them and let sit for a week. They returned to normal size/weight. I did this whole process again at 190 F and again at 200 F. A week after the 3rd session the top did stay shrunk a bit and was about the same weight or a bit less but can't be sure (my scale reads in increments of 1/2 oz but not in grams so it's not too accurate). The main thing I noticed was that the pitch stopped coming to the surface after the second session. I didn't really notice a change in stiffness or the sound of the top when tapped or scratched. I guess I could have done deflection tests for before and after but didn't think of it.

I guess the only thing that this might do is get rid of some of the pitch in the wood that might mess up the finishing process if the pitch rose to the surface under a new finish. I don't think that well seasoned tops have this problem. Has anyone had this happen to them using a not-so-well seasoned top (6 months - year old dried)?

Make sure if you do this to keep the temp under 200 F, keep the wood at the very top of the oven with space all around and not too near the sides. If anyone has any idea why this baking might be beneficial please inform me. I guess I still would rather just buy more topwood than I need and let it season/air dry for 3-5 years before messing with it. I don't think baking a top does the same thing as seasoning for years anyway. Seasoning involves more than just "setting the pitch" in a top like the baking does. Just my .02 guys.

Later-John Lewis38998.8550115741
Author:  Brock Poling [ Sun Oct 08, 2006 12:15 pm ]
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First off... this is not is not a substitute for allowing woods to dry and stabilize. I don't think the factories use it for that either.

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.

Secondarily, if it crystalizes the pitch / resin this may help improve the sound... but I suspect much of the theories about this are more conjecture than empirical... but I think it makes sense.

...
Author:  RCoates [ Sun Oct 08, 2006 12:17 pm ]
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I was under the impression that the only real benifit to cooking tops is that it may tend to make them a bit more deminsionally stable. "Aging" them is something so subjective I dont know how you'd ever prove a benifit.
Author:  Grant Goltz [ Sun Oct 08, 2006 2:08 pm ]
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This is, in my opinion, a lot of snake oil. Wood changes size with moisture content changes and unless you do something to totally prevent moisture content changes, like impregnate it with a resin or something, it will always do so.

If this actually worked, the larger woodworking industry would have latched onto this decades ago.

But if you really believe that it does something, and it makes you feel better, go ahead and do it. I will sit on the sidelines

Grant
Author:  old man [ Sun Oct 08, 2006 2:27 pm ]
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I agree with Grant. If you're cooking to solve a pitch problem, it should help with that, but the wood is going to absorb moisture, regardless, to reach equilibrium with the environment it is in. I don't believe there is any benefit in trying to reach a moisture content below 6 or 8%, because it will not stay any lower unless you live where the humidity is about that low.

Ron
Author:  Don Williams [ Sun Oct 08, 2006 2:29 pm ]
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Well, I can't speak intelligently about all this, but I will say that some very BIG names in the handmade guitar industry are doing this, and they feel that they are getting results. So I'm not sure it's snake oil...
There does seem to be something to baking the sap out and crystalizing the resins from what I keep hearing. That's not snake oil, it's science. Whether it's good science or not, I can't say, but you can't dismiss it out of hand when you know some of the folks who are doing it.
Author:  PaulB [ Sun Oct 08, 2006 2:43 pm ]
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Brian Burns is one of those folks, he found that the Q value for the top improved after baking. I think he was posting his results over at mimf a year or two ago, or it might have been at the left brain luthiers yahoo group.

Another benefit, or so the thinking goes, is that if you dry out a well seasoned top, to as close to 0% moisture content as you can get, it will never go back to the same dimension it was when it was at %8, even when you take it back up to %8 moisture level. So the main benefit is in preshrinking the top so that it is less likely to crack when used to build a guitar, and if it did crack then the crack would be more likely to close up with humidification.

Snake oil or not, I don't know, but if it does no harm then why not give it a go?
Author:  Rod True [ Sun Oct 08, 2006 2:52 pm ]
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It amazes me the factoids that comeout when a topic like this comes up. Everyone has an opinion, and that's a good thing, don't get me wrong.

To the question at hand though.

Brock, I would think that pre-baking before joining may be the way to go if you use your oven.

The "hot box" idea sounds like a good one, I bet you could get it quite accurate with a couple different light bulbs and a foil lined box.
Author:  Brock Poling [ Sun Oct 08, 2006 3:13 pm ]
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[QUOTE=Don Williams] ...some very BIG names in the handmade guitar industry are doing this,[/QUOTE]

Yeah... very big.
Author:  Billy T [ Sun Oct 08, 2006 5:41 pm ]
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   I read somewhere that the human ear can sense vibrations with a wave length the width of a hydrogen atom or one dalton. If that's the case, maybe baking the top, very well, may make a perceptable difference.

      Maybe, trying beef broth and a mirepoix(carrots onion and celery) would add a new dimension to luthiery.

Sitka Almondine (clarified butter and toasted almonds)?
Engelmann Bourguignon?
Western Red Cedar.... En Croute?? Yum!!!

I'm JOKING!!
I think it's a great idea. Please let us know what you think happened will you Brock?
   
   I going to get something to eat!
Author:  Serge Poirier [ Sun Oct 08, 2006 5:47 pm ]
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Man, i don't even have a micro-wave in my shop and now an oven? Gotta pay for my van first!
Author:  PaulB [ Sun Oct 08, 2006 6:06 pm ]
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Well, I baked all the tops I bought over the last year, with the exception of a very nice redwood top that the Don sold me (I only had the one). I work in a lab with a large oven that has very accurate temp control, so I get everything shipped to my work, bake it and then take it home.

For Lutz, euro, and red spruce I couldn't say with a high level of confidence that there was a perceptable change in tap tone after baking. I "think" there was, but it's difficult to be sure that I wasn't just hearing what I wanted to hear. I didn't have the means to accuratly measure. However, with the king billy pine tops there was a huge difference. The tap tone rang for much much longer after baking. King billy is very similar to redwood so think of a redwood top that is significantly improved in terms of sustain in tap tone after baking.

I think there is something in baking tops but my experiment was flawed in that I don't know how dry all these tops were prior to baking. It may only improve tops that are still a bit green, and it may only "improve" them to the state they'd be if they were only air dried/seasoned. But as I said before if it doesn't harm them and there's a possible benefit in "pre-shrinking" them then why not?
Author:  Tom Morici [ Sun Oct 08, 2006 7:19 pm ]
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I would have to think cooking your wood should help
to stabilize wood movement to some degree.
My concern is if we are cooking out some of the
essential resins and oils etc. Are we cooking out some
of the "life" in the wood? It is just a thought.
Who knows for sure what effect this has.
Interesting topic just the same.

Tom
Author:  Grant Goltz [ Sun Oct 08, 2006 11:14 pm ]
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Well, maybe we should forget all the air drying, seasoning, and such and just BRING ON THE KILN DRIED WOOD, the more severe, the better.

Man, I have never done anything just because some BIG NAME does it. They can be just as wrong as anybody

Grant
Author:  Brock Poling [ Sun Oct 08, 2006 11:25 pm ]
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What did I say? You seem to be ignoring the part where I said this has nothing to do with my normal drying or stabilization process. All of that is the same. Gheesh....

and.... regarding the big names... I agree that you should not be a lemming and do it simply because they do. However, there is a lot of good evidence to support that cooking the soundboard helps AND they do it (and I presume they actually know a thing or two about building). So usually, where there is smoke... there is fire.

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