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PostPosted: Fri Mar 09, 2012 1:48 pm 
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I thought I was not going to be building anymore and didn't put away any tops for future use. Now I want to build, so my question is...when you purchase tops from a supplier, how long is the minimum amount of time they should season in your shop before building? Thanks, Wendy


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PostPosted: Fri Mar 09, 2012 2:07 pm 
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I like my wood bone dry 5yrs minimum, started out doing vln/bow work so IMHO that is what I use as a baseline.Have seen many problems on fingerboards and bridges with factory instruments that moved, but that can happen even with so- called dry wood. I have a moisture meter, and check weights constantly with a gram scale., and write down date, and gm, weight on wood till it remains the same


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PostPosted: Fri Mar 09, 2012 2:49 pm 
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If you have Kiln dried you should be good to go. Air Dried a year should be fine but the longer you can keep it the better.

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PostPosted: Fri Mar 09, 2012 3:16 pm 
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Once spruce has reached equilibrium moisture content in its environment, does older wood move less than younger spruce? Seems like once it's at equilibrium it should be pretty stable, but maybe I'm missing something. I would think that a thin slice of spruce would reach a stable state before ebony would.

I know some folks "bake" spruce and then allow it a couple of weeks to return to equilibrium...would that speed up the stabilization process?


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PostPosted: Fri Mar 09, 2012 7:59 pm 
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Todd Stock wrote:
If over .125, I marinate overnight; otherwise 5-6 hours.


Thanks for that helpful bit, Todd. How do you season?


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PostPosted: Fri Mar 09, 2012 8:49 pm 
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I've always thought of "seasoning" as exposing cut wood to many cycles of heat, moisture, cold and dryness to stabilize the cellular structure. I really don't think wood that has been cut in the last two or three years can be thought of as seasoned no matter what the moisture content is.
After seeing discussions here and talking to people like Frank Ford and a violin maker I know, I bake my tops and I think that helps especially if they were recently cut (within the last 4 or 5 years) or I don't know when they were cut. I've got some 25 year old Sitka tops that I think are just fine without baking.
I'm really interested in hearing from more folks here on this topic.

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PostPosted: Fri Mar 09, 2012 10:40 pm 
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Oh! I was thinking, salt and pepper, to taste! :D

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PostPosted: Sat Mar 10, 2012 12:07 am 
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Wendy:
If you don't have five years to wait :D
One of the best pieces of advice I ever got was to weigh your wood with a small, cheap gram scale from Harbor Freight. When you get the new wood weigh it immediately, after a week or two (especially in Phoenix) you will see a dramatic change in the weight. A month after its stopped rapidly changing it would probably be useable. Afterwards, I bake the tops, it seems to change the wood for the better.I really think you can feel and hear the difference in the wood. Search the archives for the times and temps.

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PostPosted: Sat Mar 10, 2012 9:55 am 
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Hi Mike, so you bake the wood after it stabilizes? I don't know why I had just assumed that you would bake it as soon as you got it. I'll see what I can find in the archives about times and temps. 36 hours of having an oven on here in Phoenix is not a pleasant thought.


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PostPosted: Sat Mar 10, 2012 10:04 am 
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I like to bake my tops for 1 to2 hours at 200 degrees, after they have reached EMC.

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PostPosted: Sat Mar 10, 2012 10:27 am 
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callyrox wrote:
Hi Mike, so you bake the wood after it stabilizes? I don't know why I had just assumed that you would bake it as soon as you got it. I'll see what I can find in the archives about times and temps. 36 hours of having an oven on here in Phoenix is not a pleasant thought.


Wendy - the 36 hours was not a serious suggestion. As Chuck said, I think 1 - 2 hours is typical.


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PostPosted: Sat Mar 10, 2012 11:05 am 
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You can make a nice heat box with a light bulb. I use a heat blanket and heat to 300 for 3 minutes and then hold 220 for 5 just before glue up. .
A light bulb box made of plywood and cover the inside with insulation and foil . You can set up to control the temp easy enough with wattage and light dimmer. You know you are at eqilibrium then the top stays flat. The dry side will cup up.
It does seem older wood is often more stable .

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PostPosted: Sat Mar 10, 2012 12:11 pm 
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Wendy - the 36 hours was not a serious suggestion. As Chuck said, I think 1 - 2 hours is typical.[/quote]


duh


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PostPosted: Sat Mar 10, 2012 8:35 pm 
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I used to give it at least 3 months from when I received it most likely from LMI. This was a very long time ago and now I have supplies years old and build far less so it's not an issue.

I've yet to see one of those old guitars come back with cracked tops.

I could be wrong but I always felt that you want the wood to reach your shops moisture content and that, for such thin wood, really would not take more than 3 months. And once in that environment and stikered properly what benefit would holding it for years do?

I've heard that air drying goes through so many swings and cycles that if the wood survives it then you probably got some good stuff, I can see that. But once stable in any relative environment what is the benefit of age?


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PostPosted: Sun Mar 11, 2012 12:23 am 
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Todd Stock wrote:
36 hours is a very serious suggestion - more than that, it's what I do. A lower temp bake works the same as a high temp bake, except less stress on the wood. 160 degrees for 36 hours works nicely.


Ah, for some reason I thought you were joking. My bad.


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PostPosted: Sun Mar 11, 2012 2:36 am 
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Quote:
I've heard that air drying goes through so many swings and cycles that if the wood survives it then you probably got some good stuff, I can see that. But once stable in any relative environment what is the benefit of age?


i agree...torture the wood, and what comes out the other side unscathed is the keeper wood


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PostPosted: Sun Mar 11, 2012 3:14 am 
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callyrox wrote:
36 hours of having an oven on here in Phoenix is not a pleasant thought.
Why would someone have an oven in Phoenix?? Are they walk-in? :D

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PostPosted: Sun Mar 11, 2012 9:22 am 
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Billy T wrote:
callyrox wrote:
36 hours of having an oven on here in Phoenix is not a pleasant thought.
Why would someone have an oven in Phoenix?? Are they walk-in? :D


Hey now that gives me a great idea! I can just bake them in the summer without having to turn on an oven, just make some kind of enclosed box for outside! All I have to do is some tests as far as constant temp so I know how much direct sun or shade! :lol:


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PostPosted: Sun Mar 11, 2012 10:13 am 
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Like most new processes in guitarmaking, baking wood has a very long history. 19th century Spanish makers stored their wood on their Azoteas, or flat roofs, under a corrugated tin roof, the wood went through a daily round of baking under the hot sun, and night time cooling. This could go on for years. The Azotea of Torres last house in 80 calle Real, Cnada de San Urbano can still be seen.

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PostPosted: Sun Mar 11, 2012 12:05 pm 
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So, I am in Tucson. I sticker my wood in a room with 40-45% RH at all times. Are you saying that, once the wood has stopped changing weight and acclimated to my environment, I should bake all the moisture out of it? Do you then build with it "dry" or do you put it back in your controlled RH environment? Further, my builds take so long at this point that any baking out of moisture I would do would be reversed by the time I glue it up. I'm sure I'm just missing something in my interpretation!


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PostPosted: Sun Mar 11, 2012 2:33 pm 
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I don't know how much "science" is behind baking tops.............but, baking at least for me isn't just about removing the moisture. It's also about cooking/setting the resins. I also believe there's some trapped moisture that won't come out with normal drying. I dry mine normally, then bake a couple hours at 200 degrees. I let it re acclimate before building. Todds method of a longer bake, at lower temps make sense, but I wouldn't want to leave them baking un attended for that long.

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PostPosted: Sun Mar 11, 2012 3:00 pm 
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I`m not convinced that baking tops is the right thing to do.According to a fellow builder who runs a kiln here in Tennessee,drying out wood too quickly can cause case hardening which can cause problems in the future.He says that they kiln dry wood to a moisture content of 6 percent and that it always comes back to equilibrium at around 8 to 12 percent anyway depending on species.He has been running a kiln for thirty years.That`s a bunch of knowledge about wood.He says if the woods moisture content is around that 8 to 12 percent you should be good to go.He`s uses a wagner moisture meter to measure moisture , even thin pieces.He says you have to stack several pieces together,lets say several tops of the same or similar pieces that have been sitting in your rh room ,you can get an accurate enough reading.I`ve often recieved back and side sets ,that if I put in my rh room even stickered will try or does twist and warp.He says this is due to drying out to quickly.I`ll be receiving a wagner moisure meter the first of the week ,I`ll see if it helps.This way I can get a good educated guess as to the moisture content when I recieve wood and before I use it.If it`s way above 12 percent ,he suggested stickering it in my basement shop where the rh isn`t regulated and blow a small fan on it for a few weeks and check moisture again.Eventually it should be able to go to the rh room and not go nuts.I hope I didn`t get on a whole other subject.
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PostPosted: Sun Mar 11, 2012 8:18 pm 
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I`m no expert with wood ,I`ve only been making a living working with it for 40 years.I`m not trying to be a smart ass,but I have seen plenty of wood that`s only 3/16 thick that has gotten warped and twisted very badly due to being brought into the shop because it`s moisture content was very high,and the dryer conditions in the shop caused this.This is what the kiln owner considers case hardening.He`s also a fellow guitar builder and has worked with thin woods and he doesn`t recommend baking tops because he says it can cause case hardening.His words not mine.This simply means as I understand it that the outer surface of the wood dries faster then the interior and causes stress.I`ve had back sets that you could flex and it would stay out of wack and then you could flex it back the other way and it would stay out of wack the opossite way.Also cutting wood like this usually causes it to crack,relieving the stress.because it`s been case hardened.I`m sure most of us that have worked with wood very many years have experienced this.As I said I`m no expert ,and this may not be the true definition of case hardeneing.I know for a fact that it`s WOOD GONE WILD.I think knowing the actual moisture content of the wood before building with it to me any way is more important than cooking a top which does what ?I have no clue or should I say proof that it does anything except appeal to some of the folks that do it.Which is cool if it makes your boat float.As you have said Todd if the wood your baking is already well seasoned than I don`t see how baking can hurt.I`m just not convinced it helps,so why take the chance that it could hurt.
[:Y:] James

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PostPosted: Sun Mar 11, 2012 9:05 pm 
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I resaw a bit of guitar and mandolin tops from green (wet) spruce. After cutting, I store and dry it in a non humidity controlled part of my shop, for years. Out of curiosity, I have also kept a few pieces in the humidity controlled part of the shop, to measure its weight over time, and see how it develops. In a 5-7 mm thick piece of spruce such as a guitar top, at 20 degreees C / 45% RH, stickered normally (no fan), most of the water is gone in a week. After 3 weeks to a month, no change in weight can be measured, and I suppose, it could be used for an instrument. I have never tried using wood that fresh, and I wouldn't recommend it, in fact most of the wood I use has been in my shop 5 years or more by the time I get around to building with it, but OTOH, I can't really say I think it is absolutely necessary for structural reasons. I did once make an arch top mandolin, with a top that I had cut only 3 months before, and its still holding up, as far as I know; "seasoning" while also being an instrument... If you do the "fingernail test", it does seem like the wood gets a little harder over time. Most houses up here are built from local spruce, and I have salvaged some pieces from renovation projects and torn down buildings, some one hundred years old or more, and used them mostly for braces. This wood is noticeably harder to carve than younger wood, and seems really stiff and resilient, excellent for braces.

So, there's your answer; a short time is OK (probably), but longer is better ;)

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PostPosted: Sun Mar 11, 2012 9:47 pm 
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I didn't read this recently but have read that air drying removes moisture between cells while kiln drying removes this moisture plus the moisture within the cell walls. Afterwards, the moisture between the cell walls is reabsorbed but the moisture isn't reabsorbed within the cell wall so that is a permanent loss. If true, this would likely increase the stiffness to weight ratio. I can't vouch for that info, just what I've read

Im speculating here, but I would guess that over time (maybe even decades) that wood does loose moisture within the cell wall and possibly this is what gives old instruments that "dry" sound. Maybe it's also what increases stiffness in older wood as Arnt mentioned. So possibly baking in an oven also removes moisture within the cell thus artificially speeding up the aging process.

Be sure and sticker a top flat immediately after removing from an oven. It may want to twist and once the resins set, it will remain in that warped state. I ruined a good top as I didn't know to sticker and haven't been able to flatten it by re-heating, steaming, or any other method.

Not sure how thin wood would case harden.

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