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Old 06-30-2015, 12:04 AM
Sam VanLaningham Sam VanLaningham is offline
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Default Air Drying Times + Air vs Kiln Drying....

Hello All - So I ascertained some much better englemann windfall (much better than the stuff I posted awhile ago....and even meets some "moon spruce" criteria) and have split 4 gigantic rounds into bolts, if you will. Its pretty dry now (I have used the remnants in the fire pit and it indeed burns, though a bit slow with bigger chunks). Ive resawn quite a bit of it recently and the tap tones are really really really good. And its really stiff stuff as well. So I want to build with it!

AIR DRYING DATA
Anyways, Ive been plotting mass of one smaller bolt (split wedge) since I split it to get an idea about moisture loss. Essentially it lost most moisture in the first couple weeks and now is on a slow linear trend that could reach its equilibrium moisture content (EMC) for the region I live in anywhere from 70 to 120 ish days. Many say "wait several years" but it seems like it would be dimensionally stable once it reaches EMC (as long as it doesnt move on to a new locale with a drastically different EMC).

Additionally, I have also been tracking moisture loss in a resawed piece 0.175" x 4" x 20". Its quite dry and has stayed relatively flat since resawing (without stickering). I also put it in oven at ~200F for 2 hours. It went from 120 g to 112 g. It has since regained moisture and stabilized at 117 g.

Generally I wonder if I should go for it after 4-5 months? I also wonder if LMI etc wait 1-3 years for topwood to dry before selling?

AIR VS KILN DRYING
Sooo, "everyone" seems to poo poo kiln drying, saying it robs tonewood of its tone etc. However, Bob Taylor among others is a big fan of "baking tops", drying spruce tops at 200F for a couple hours. Others have demonstrated that stiffness increases after partaking in this practice. So, Im just wondering if I can let dry for 4 months and then bake a top and build with it without losing any tonal potential it has?

Thanks for reading and offering up any thoughts! Sam

engelmann_drying_2015 by Sam VanLaningham, on Flickr
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  #2  
Old 06-30-2015, 12:55 AM
Frank Ford Frank Ford is offline
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I suspect you'll want to read up on kiln drying and seasoning wood.

For example, I believe Taylor, Collings and others oven-dry spruce to make it less susceptible to future cracking when a guitar is in a dry environment. It's not a process intended to improve tone.

LMI and other wood suppliers use kiln drying to equilibrate woods to ambient humidity, and it's often a matter of slowing moisture loss to avoid cracking tropical and delicate hardwoods.

Offhand, I don't recall hearing any particular talk about kiln drying in regard to tone - either improving or degrading it.

Traditional air drying often meant that wood went through many cycles of higher and lower humidity, especially when left in covered open sheds outside in the elements. Conventional wisdom is that wood becomes less reactive after years in that kind of storage. That is more what the "cooking" is about - gaining stability. That kind of low-isn temperature cooking is to be distinguished from the current fad of high temperature controlled atmosphere torrefaction which is more about tone, stiffness, etc.

When I asked the folks at Collings if they cooked all their guitar tops, I received my answer: "Yes, but they are BAKED, not FRIED. . ."
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Last edited by Frank Ford; 06-30-2015 at 07:19 AM.
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Old 06-30-2015, 06:21 AM
B. Howard B. Howard is offline
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The general rule of thumb for air drying lumber is 1 year per inch of thickness. A 4/4 board will be ready and stable after a year, an 8/4 will need two years.

KD lumber, done properly will bring the moisture content of the lumber close to 3% at the very center of the board. This is lower than the lumber will ever likely see in service and by doing so will increase the stability of the lumber. After this the lumber will need to "rest" or acclimate back to the MC dictated by the current environment. This will depend on thickness, we used to rest the 4/4 2-3 months before cutting.
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Old 07-01-2015, 10:09 PM
Sam VanLaningham Sam VanLaningham is offline
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Ok I like what I'm reading here! Very helpful. Thanks.


Seems like if the wood that I've resawed (resawed after about 1 month of drying; ie after moisture loss rate slowed considerably) should be ready quite quickly because it's ~0.2" thick at most, 70 days or so based on the year/inch rule of thumb Brian noted.

I'm going to do some tap tone tests on kiln vs air dried to see if I can tell a difference.

Cool. Sam
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Old 07-01-2015, 11:22 PM
John Arnold John Arnold is offline
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Actually, 70 days is much too long for 0.2" thick spruce. I typically cut red spruce tops when the wood is green, because letting it dry in billets invites problems with cracking and blue stain.
A sopping wet guitar top will be dry in a few days if it is put on sticks and a fan is used.
There is no problem with warping of quartered spruce.
Although the wood will be stable once it reaches equilibrium moisture content, it may take over a year for the pitch to crystallize at ambient temperature. The good news is that you can 'set the pitch' in a few minutes by warming the wood to about 180 degrees.
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Old 07-08-2015, 07:13 PM
Sam VanLaningham Sam VanLaningham is offline
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Quote:
Originally Posted by John Arnold View Post
Actually, 70 days is much too long for 0.2" thick spruce. I typically cut red spruce tops when the wood is green, because letting it dry in billets invites problems with cracking and blue stain.
A sopping wet guitar top will be dry in a few days if it is put on sticks and a fan is used.
There is no problem with warping of quartered spruce.
Although the wood will be stable once it reaches equilibrium moisture content, it may take over a year for the pitch to crystallize at ambient temperature. The good news is that you can 'set the pitch' in a few minutes by warming the wood to about 180 degrees.
Excellent info, john! Thanks so much. This is where intuition and some empirical results were leading me so it's nice to hear from a guy with your experience. Cool.

Sam
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