Official Luthiers Forum!

I usually just take mine down to my local rocket propulsion lab and stick 'em in the wash... its way faster.. I mean really really faster...

Chris--

Nice Mach diamonds in that motor wash.  Is that puppy throttlable?

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Jim Howell
Charlotte, NC

Here is what I have noticed in mine after baking:

The wood is much drier than it was before, so sanding it is a little more difficult due to the harder surface of the wood. Once it is sanded smooth, I dont notice the ripples of the seasonal growth rings showing up in the finish of the guitar like they do on a non-baked top.

I dont think it makes a hill of beans as far as tone is concerned.

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Reguards,

Ken H

Brock and Mario nailed it in my view.

It is not the same as kiln drying and the reasons typically used to kiln dry lumber.  In kiln drying excess moisture is removed at a far greater rate then just letting the wood season and dry over time.

We bake out tops to stabilize the wood, remove moisture, not excess moisture, AND dry up to some degree and pitch pockets.  the molecular structure is altered and as mentioned the wood is slightly condensed to no longer have the areas where the excess moisture molecules were located and these areas are condensed as a result.  When the wood acclimates to normal RH levels over time it no longer has the same degree of voids to contain moisture.

The tone benefit comes from a now more homogeneous piece of wood requiring less input to excite it.  Same for the power and projection.  The tops that I have baked go into the oven being what ever species that they are and come out feeling more like and sounding more like Adi IMHO.

The analogy might be taking a sponge and heat shrinking it.  When done it is stiffer, thinner, and will hold less moisture in the future because the voids have shrunk and these voids are where the water molecules would exist.

It is also a best practice of the major factories too from what I understand or at least Taylor.

I would not think that a microwave would work for why we do this.  Again I can see wet wood being dried in a microwave but we are not baking wet tops.  We are taking acclimated tops and further stabilizing them and baking out the pitch pockets.  Microwaves heat food by exciting the water molecules but do not heat molecules that do not contain moisture.  This of course will heat the surrounding food, wood, etc.  But it is also the reason when some things are "microwave save" they contain no moisture like plastics etc.

As for the wood being harder I have noticed this too but prefer it.  It's now more of a plate and less of a blanket.

Here is a link to Brians wood testing site.
Also we went further in testing cooked wood 1 side cooked the other left uncooked and then retesting it a year later. Its did get 21% higher Q. cooking so the pitch was set.  Also stops the pitch from eating at the finish.
mario
http://www.lessonsinlutherie.com/woodtestingandvoichirez.htm l

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Kent,

I would love to see that photo if you don't mind. I have a basic idea but would like to see what others have done. Thank you!

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Burton
http://www.legeytinstruments.com
Brookline, MA.

My wife will be shocked that I know how to operate the oven

Anthony,

The trick is to use the oven when She's not home.

Peter

Hello again. I haven't been here for so long I had to re-register.

I cook all my tops. Don't see any harm and trust that those who recommend it know what they are talking about. 

I have a gas convection oven that works fantastic.  Because it is gas the environment is actually pretty moist at 200 degrees. I doubt I am removing any moisture at all but I haven't tested it.  Now, if it were electric that would be another story. Electric ovens are dry. That is why bakers prefer them and roasts or turkeys do better in gas. Still, the air in an electric oven has a certain amount of moisture to begin with and that does not leave if you keep the door closed.  Sure, there is some venting going on, but the replacement air has moisture in it as well correct?  The RH will drop as the temperature rises but as some have said above, the wood will re-acquire most if not all of the moisture when it acclimates again. I always let the tops rest for a week or more before bracing.

Hoadly talks about free moisture and trapped moisture in the cell structure.  If your top is already dry then most of the trapped moisture will be long gone and you will only be manipulating the free moisture (The stuff between the cells not the stuff inside the cell wall.)  Cooking the tops is not about drying the wood. As said above it is about setting the pitch, or pre-stressing the wood. However you wish to view it. It should be done with wood that is already dry. If you try to dry green wood in the oven, expect some very expensive kindling will be the result. 

I wonder if the big boys inject or otherwise monitor the moisture in the air as they cook their wood? It is a very short duration that we do this so I wonder if the drying effect is minimal? The pieces are thin, so moisture migration will be quick and relatively even compared to 4/4 or larger material. Is that why we don't get checking problems when we cook our tops? Does anyone with an electric oven put a pie tin full of water in with the wood to keep the RH high? Should you? Would it defeat the purpose of cooking the wood?

Dehumidification is not the same as heat.  I would be reluctant to dehumidify my tone wood storage in any severe way. Keeping excess moisture out is one thing. Making it bone dry is another.

The light bulb thing sounds more like a drying process or storage control than what the cooking is supposed to do. A good tool to use, but not the same purpose.

Greg N

Hoadly talks about free moisture and trapped moisture in the cell structure.  If your top is already dry then most of the trapped moisture will be long gone and you will only be manipulating the free moisture (The stuff between the cells not the stuff inside the cell wall.)  Cooking the tops is not about drying the wood.

That's what I was getting at in my earlier post. Kiln drying may or may not be equivalent from one supplier to the next. If not done well, there may still be bound water in the wood. In that case, baking the tops should get rid of the remaining bound water and the stiffness/weight ratio may improve. On the tops I tested, it did not.

Burton, I'll get a photo this afternoon.

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http://www.chassonguitars.com

Without opening up the whole kiln dried vs. air dried debate I have to say that with as thin as tops are cut my experience is that if I store them in my loft, properly stickered they get down to 8-9% moisture within two years.  Patience is a virtue.

Greg N 

Does the spruce smell up the room any when you bake them? I have noticed even cutting spuce soundboards, it smells 'like pine'.

Yep there is a pleasant smell to it.  Be sure to keep a clean oven or your guitars will smell like roast beef.........

When I cook my tops I place 3/16" t0 1/4" spacers that extend beyond the width of the tops and bind the whole thing together with cooking twine. It keeps the whole package together and helps keep the tops flat. It works well for me.

Peter L

My oven isn't big enough for top wood.  I have a narrow oven, and it's only 20" deep.  Maybe I should just store my tops in the attic.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

we should all store our woods in the attic. But remember to take them out a year ahead of time to acclimate back to the shop.

Y'all wouldn't believe where I store my wood stash....

[QUOTE=psl53]

Anthony,

The trick is to use the oven when She's not home.

Peter

[/QUOTE]

Peter, right you are! Should have thought of that myself!!

[QUOTE=BlackHeart] Does the spruce smell up the room any when you bake them? I have noticed even cutting spuce soundboards, it smells 'like pine'.
[/QUOTE]
Mine smell like Spruce

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Guitars, guitars and more guitars.

[QUOTE=WaddyT] My oven isn't big enough for top wood.  I have a narrow oven, and it's only 20" deep.  Maybe I should just store my tops in the attic.
[/QUOTE]

I have that problem too... however if you watch craigslist you can find them REALLY cheap. Cheap enough that you could have a dedicated one for the shop.

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

Thanks everyone,
What thickness are the tops you bake?

Bob buddy since the tops are baked before joining and you want the baking to be effective (meaning not starting out with something to thick) I bake at .145ish for one hour at 200 and leave it in the oven for about another hour while the oven cools down.