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Old 09-24-2009, 09:19 AM
rattletrap rattletrap is offline
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Default Wood Seasoning

I've been doing quite a bit of reading regarding the woods on a guitar.

It is pretty much a consensus everywhere that wood that has seasoned for years is better.

A while back I read a research article on why Stradivarius violins sound so good. This article proposed that the reason that the violins had sweetened was due to the cyclical nature of the seasons wetting and drying the wood.


I have also read that people are baking their spruce tops. They are saying that baking the tops crystallizes the saps and resins in the wood. baking the tops at 320F is certainly more than kiln drying.

I live in an EXTREMELY dry climate. The humidity averages below 20%. In addition to the low climate it is hotter than blazes. In addition to that it is incessantly windy.

Wood drying out is a real issue here. Over time the desert dessicates wood that is outside. Considering how dry it is here I could quickly cycle wood through wet and dry cycles. I think that this would tend to simulate years of aging in a short time. I could sticker up some wood, wax the ends and simply set it out on the driveway in the summer and it would dry out in a couple days. The hot dry air would act as a slow kiln.

Luthiers,

What are your opinions on this?


Craig
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  #2  
Old 09-24-2009, 09:35 AM
JohnJayPl JohnJayPl is offline
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I have also read that people are baking their spruce tops. They are saying that baking the tops crystallizes the saps and resins in the wood. baking the tops at 320F is certainly more than kiln drying.
Who is baking at 320F?

Taylor bakes at 200F and that's the usual number you hear about folks using. Some go a bit lower.

John
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Old 09-24-2009, 09:50 AM
rattletrap rattletrap is offline
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This is off of a thread in a luthiers forum that I've been reading. I should have said 390 degrees..........




Received my latest issue of "Wood & Steel" which is the Taylor Guitars periodical (and generally a good read), and they had a feature article on "Seasoning Tonewood"

Quite the eye-opener

"Most wood gets moved to the Kilns when it reaches 12 - 15% MC from air-drying, except Cocobolo, and Mad Rosewood. The general drying cycle in the kiln lasts a week. Temperature is increased daily up to the kilns highest temperature of 270 Degrees Fahrenheit. The Cocobolo and Mad Rosewood are kept in a climate controlled area until we're ready to "slow-dry them in the kiln, according to Chris Cosgrove." (He does not elaborate on the "Slow-Dry" kiln procedure).

"SPRUCE and EBONY are seasoned differently from our other tonewoods. After the stickering process, instead of being kiln-dried, the the wood goes into an oven, where it's baked at about 200 degrees Celsius (392 fegrees FAHRENHEIT) for about 2-3 hours."

"Spruce is very stable, can handle high temperatures, and it won't move. Baking the Spruce also hardens the sap resin in the wood"

"Ebony's extreme density makes it immune to cracking in the higher heat, and it won't shrink. It's also the most difficult wood to successfully dry - not because it cracks or warps, but because it doesn't lose moisture easily. Baking it facilitates the release of bound moisture"

"If we took wet wood and brought it down to 47 percent (RH), you'd have a larger piece of wood than if we dried it all the way down to 0 percent, and brought it back up to 47 percent", explained Bob Taylor...............
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Old 09-24-2009, 09:57 AM
JohnJayPl JohnJayPl is offline
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Quote:
Originally Posted by rattletrap View Post
This is off of a thread in a luthiers forum that I've been reading. I should have said 390 degrees..........




Received my latest issue of "Wood & Steel" which is the Taylor Guitars periodical (and generally a good read), and they had a feature article on "Seasoning Tonewood"

Quite the eye-opener

"Most wood gets moved to the Kilns when it reaches 12 - 15% MC from air-drying, except Cocobolo, and Mad Rosewood. The general drying cycle in the kiln lasts a week. Temperature is increased daily up to the kilns highest temperature of 270 Degrees Fahrenheit. The Cocobolo and Mad Rosewood are kept in a climate controlled area until we're ready to "slow-dry them in the kiln, according to Chris Cosgrove." (He does not elaborate on the "Slow-Dry" kiln procedure).

"SPRUCE and EBONY are seasoned differently from our other tonewoods. After the stickering process, instead of being kiln-dried, the the wood goes into an oven, where it's baked at about 200 degrees Celsius (392 fegrees FAHRENHEIT) for about 2-3 hours."

"Spruce is very stable, can handle high temperatures, and it won't move. Baking the Spruce also hardens the sap resin in the wood"

"Ebony's extreme density makes it immune to cracking in the higher heat, and it won't shrink. It's also the most difficult wood to successfully dry - not because it cracks or warps, but because it doesn't lose moisture easily. Baking it facilitates the release of bound moisture"

"If we took wet wood and brought it down to 47 percent (RH), you'd have a larger piece of wood than if we dried it all the way down to 0 percent, and brought it back up to 47 percent", explained Bob Taylor...............
The 200C/392F numbers were "typos" in that wood and steel issue. Taylor printed a correction in the next issue. The actual number they use is 200F.

Quote:
Correction: In the fall 2008 issue,
our “Seasoning” feature included
a sidebar stating that our spruce is
baked in an oven at 200 degrees
Celsius. The correct temperature is
actually 200 degrees Fahrenheit.
We regret the error.


John

Last edited by JohnJayPl; 09-24-2009 at 10:03 AM.
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Old 09-24-2009, 10:50 AM
rattletrap rattletrap is offline
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thank you!

What do you think of cycling the wood thru multiple cycles of humidification and drying?
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  #6  
Old 09-24-2009, 01:48 PM
JohnJayPl JohnJayPl is offline
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Originally Posted by rattletrap View Post
thank you!

What do you think of cycling the wood thru multiple cycles of humidification and drying?
You're welcome.

I don't know about multiple cycles, I have never tried it.

One cycle, for the small number of samples I've tried does seem to shrink the wood. For example, a 210mm line across the grain once shrank about 2 mm after baking. When it gained its moisture back it only gained back about 1.75mm. What happens the next time it looses moisture? Well I havent' measured that. You really need better humidity control then I have to do these kinds of tests.

Baked wood does seem more "crispy" when I plane it but that could just be my imagination.

It takes about 4-5 days for baked wood to stabalize. If you gave it a week to be mostly on the safe side you could cycle the wood 52 times a year. Now I have no doubt that this is a pretty big stresser of the wood but is it enough to do something significiant? And what would you mesure to find out what you did to the wood? Maybe stiffness, maybe damping? This is pretty far down on my list of things to measure but if you're really interested I encourage you to do some experiments.

John
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Old 09-24-2009, 02:04 PM
rattletrap rattletrap is offline
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Actually I am referring more to air drying in this desert.

I live in a kiln, or so it seems some times. The humidity here averages below 20%. A hot summer day can suck the water out of just about anything in a HUGE hurry.

Green firewood can be seasoned in well less than a year here.

My thought is to put the top through a few cycles of humidification and dehumidification to simulate years of seasoning.
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Old 09-24-2009, 02:06 PM
Brock Poling Brock Poling is offline
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Quote:
Originally Posted by rattletrap View Post

"If we took wet wood and brought it down to 47 percent (RH), you'd have a larger piece of wood than if we dried it all the way down to 0 percent, and brought it back up to 47 percent", explained Bob Taylor...............

This is the key. THIS is the real reason for baking. The crystalization of the sap is not the primary benefit (if any benefit at all). This is like pre shrinking a pair of jeans. Once you do it they rarely shrink further and the guitars that have their tops baked fare heat and dives in humidity better.

.
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Old 09-24-2009, 02:17 PM
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I like to add some basil and a touch of garlic.
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Old 09-24-2009, 02:32 PM
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Quote:
Originally Posted by rattletrap View Post
I've been doing quite a bit of reading regarding the woods on a guitar.

It is pretty much a consensus everywhere that wood that has seasoned for years is better.

Asnip

I live in an EXTREMELY dry climate. The humidity averages below 20%. In addition to the low climate it is hotter than blazes. In addition to that it is incessantly windy.

Wood drying out is a real issue here. Over time the desert dessicates wood that is outside. Considering how dry it is here I could quickly cycle wood through wet and dry cycles. I think that this would tend to simulate years of aging in a short time. I could sticker up some wood, wax the ends and simply set it out on the driveway in the summer and it would dry out in a couple days. The hot dry air would act as a slow kiln.

Luthiers,

What are your opinions on this?


Craig
I read recently about wood that is harvested when the sap is residing in the roots (dormant?) exhibits properties of well seasoned wood.
BTW Wouldn't drying wood too quickly cause it to split from shrinking too fast? Isn't it important to remove the moisture while keeping the cell structure from collapsing appreciably? Just asking. I'm learning too.
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Old 09-24-2009, 03:00 PM
rattletrap rattletrap is offline
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Quote:
Originally Posted by Brock Poling View Post
This is the key. THIS is the real reason for baking. The crystalization of the sap is not the primary benefit (if any benefit at all). This is like pre shrinking a pair of jeans. Once you do it they rarely shrink further and the guitars that have their tops baked fare heat and dives in humidity better.

.
now that makes sense. Thank you


Quote:
Originally Posted by SteveS View Post
I like to add some basil and a touch of garlic.
Parmesan?
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Old 09-24-2009, 03:39 PM
tadol tadol is offline
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There is a whole field of study on this, but as I understand it, there are 2 types of moisture in wood - the moisture between the cells, and the moisture inside the cells. The "free" moisture has to be removed slowly, since loosing it too quickly will cause all kinds of cracking as the "trapped" moisture will keep the cells from shrinking. So you need to regulate the loss of the free moisture to allow the trapped moisture a chance to migrate out of the cells, and then slowly bring the whole piece to an equilibrium level.

When you "bake" wood, you are helping to force trapped moisture out of the cells. This trapped moisture would eventually work its way out over a period of time, but you are essentially forcing the natural process.

Trapped moisture does not get replaced - the cells do not re-integrate moisture into themselves. The free moisture is easily replaced or lost depending on the relative humidity of its environment. You slow this process by applying finish to wood, but it continues to happen.

Its usually easier to dry wood out than it is to keep it properly humidified. If you're in that dry an environment, you need to make sure you can control that or you will end up with alot of firewood quickly -

Tad
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Old 09-24-2009, 03:47 PM
rattletrap rattletrap is offline
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Originally Posted by tadol View Post
There is a whole field of study on this, but as I understand it, there are 2 types of moisture in wood - the moisture between the cells, and the moisture inside the cells. The "free" moisture has to be removed slowly, since loosing it too quickly will cause all kinds of cracking as the "trapped" moisture will keep the cells from shrinking. So you need to regulate the loss of the free moisture to allow the trapped moisture a chance to migrate out of the cells, and then slowly bring the whole piece to an equilibrium level.

When you "bake" wood, you are helping to force trapped moisture out of the cells. This trapped moisture would eventually work its way out over a period of time, but you are essentially forcing the natural process.

Trapped moisture does not get replaced - the cells do not re-integrate moisture into themselves. The free moisture is easily replaced or lost depending on the relative humidity of its environment. You slow this process by applying finish to wood, but it continues to happen.

Its usually easier to dry wood out than it is to keep it properly humidified. If you're in that dry an environment, you need to make sure you can control that or you will end up with alot of firewood quickly -

Tad
I am constantly concerned with humidity around here. Its a never ending battle
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Old 09-24-2009, 04:24 PM
Jeff M Jeff M is offline
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One question I've had for awhile re; wood seasoning and guitars like Blueberry built in Indonesia.

I may be wrong here, but I got the impression that Blueberries production site did not have access to/use a kiln/seasoning room?
If that is the case (or if it isn't, and as a hypothetical question).....how do they season their wood? Wouldn't it be prone to warpinig, splitting, coming from such a humid environment?
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Old 09-24-2009, 08:50 PM
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A lot of people seem to have to work harder than they need to.
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