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I hear/read about seasoning quite a bit, but I haven't come accross any "ho-to" or specifics on when the wood is ready to be used for an instrument.
I'm sure there are as many opinions on this as there are ways to build a guitar, but I wanted to try and get a feel for what some of you are doing.
Do woods need to be seasoned to a specific climate/region before use if imported from elsewhere? Example: Humid west coast product imported to ultra-dry Colorado.
How long from kiln dried does a person need to season a piece of lumber before use? Air dried?
Any general guidelines/notes of experience would be greatly apprecieated.
Thanks.

-j.

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“If God dwells inside us like some people say, I sure hope He likes enchiladas, because that's what He's getting”
-jack handy

I prefer the term 'acclimatized' or 'well dried'. 'Seasoned' sounds like I'm adding spices ;-)

I prefer to let dried and ready to build with wood sit around for at least a month in my shop before working with it, doubly so if I've bought the wood by mailorder/internet with a vastly different humidity/climate.

If you're buying well-dried, whether air or kiln, ready to build with wood (which is, what, about 12% humidity, I think. I have no way of measuring wood myself), it shouldn't need much more than that to acclimatize, which is doubly true for thin plates (spruce goes quickly, rosewoods take a bit longer).

If I'm buying from sources who can't clearly tell me how the wood's been dried, how long it's been there, then (with thin stock) I leave it for 3-4 months. I prefer to just stockpile stuff, and have it for at least a year (definitely a year for ebony fingerboards, anyway) before building with it.

General guideline: if you want to build soon, buy from a reputable source (any of the OLF sponsors, really) and ask questions about the moisture content, how the wood was dried, how dry it is, and still let it sit for a couple of weeks before use. Otherwise, buy when you find something good, well in advance, and figure out what you'll build with it afterwards, instead of buying once you've got a firm design drawn up.Mattia Valente38692.6359490741

As I recall the rule of thumb is to let it dry 1 year for every inch of thickness.

Typically though I try not to build with something for at least a year... but sometimes I just can't help myself...

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

[QUOTE=Brock Poling]
As I recall the rule of thumb is to let it dry 1 year for every inch of thickness. [/QUOTE]

This will only get the wood down to the RH equallibrium of your locale (here in Ohio it's 12%-13%). This is still way to moist or green to build with. The wood needs to be in the 6%-8% range if you plan to sell and ship them around the globe. If the guitar is going to remain in your locale then you can get by with using wood that is of a higer moisture content closer to your environment.

I learned a valuable lesson the hard way and built a guitar with wood that was stored in my garage. I shipped it to Tennesee and three days later the lady called and said "the back sunk in"! It was much drier there and the wood shrank. She shipped the guitar back and in about a week the back popped back out when it had absorbed enough moisture to cause it to swell. The guitar was sold to a local person and it hasn't moved in 5 years.

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tim...
http://www.mcknightguitars.com

Cumpiano uses a closet with a light bulb on, kinda like a big fox bender. Thin tonewoods will dry quite quickly. To dry tops after I cut them I sticker them in an area that is about 70 F and put a fan on them for about 10 days. They are then dry, but once I ship them I always advise that they get acclimitized to the builders environment. I have a whole mess of electronic hygrometers around (6 I think) that I buy when ever they come on sale ($14 to $25). I make sure that my storage area is always below 45%. Many builders just make a small storage space that is controlled and store their woods for their upcoming projects in the climate controlled environment. But as Tim points out, these thin woods will react quickly to changes in humidity.

Hope this is useful

Shane

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Canada

what do you folks prefer for stickerage?

    I use plywood strips. Any thing will work. You want to have without forced are 3/4 inch to allow convection currents to flow. If you use a fan 3/8 minimum.
     I use an old chest freezer and a ceramic disk furnace. Then I stack in a way the make the air flow all around the wood. The disk furnace is used just with fan and light bulbs for heat.
   I like to get to 90 to 100 degrees for a week, I can get to 8%
john

I sticker with 1/4 inch stickers and stack on shelves with a box fan at one end. THe fan moves the air theough the stacks very well. I leave the tops stickered for 10 days at room temperature with the fans on them. You can see the system on the "process" page on my website. The important part is too ensure that your stickers are the same thickness and that your sets are also a uniform thickness so that you have unrestricted air flow through the stacks. I can do 100 sets per fan. I have four fans set up so I can do 400 sets every 10 days, when I am ambisious!

Shane

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Canada

so, 3/4" square pine or plywood in 8" long strips would be generally
adequate? Is there better / more preferable material?

Charlie,

Just make sure that if you use pine that it is dry and has not pitch that will run onto our tonewood, otherwise taht and plywood will be just fine. This topic was discussed a couple of months ago and, although many do things different, most of us tonewood guys do not sticker our wood after it is dry, we stack it in piles. If it is cut right and stored flat it will stay flat. Some like to sticker each piece and leave the stickers long so that they can tie a rope between the top and bottom stickeres to keep them tight. My concern is that the sets are only supported under the stickers, allowing the area between the stickers to 'belly'. But, there are many ways to play with this ball. This is just the way I do it.

Good Luck

Shane

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Canada

Seasoning ... is that same as drying?

I always think of seasoning as going through some cycles, like the seasons cold, warmer wet, dry hot cool dry etc kinda like winter spring summer and fall.

I would say the rosewood sets that I have that came from a 200 year old house beam in Rio deJaneiro would be well seasoned ... but what are the seasons like there?

One the other hand most of my wood sits in my shop at 40-45% humidity most of the time. Is is seasoning in this constant envirionment?

Just thoughts ... no conclusions

I think of seasoning as pass the salt and pepper please. Wood that is dry sitting in a room at 40-45% humidity should be just fine. I use 1/4" plywood stickers with a fan like Shane does. Works just fine. One thing to remember as Tim points out in his post. You have absolutly no control over humidity once that guitar is in the customers hands.

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Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

[QUOTE=johno]
I would say the rosewood sets that I have that came from a 200 year old house beam in Rio deJaneiro would be well seasoned ... but what are the seasons like there?

[/QUOTE]
pretty much summer year round...although one of the coldest weekends I ever spent in my whole life was one when I was in RIO during the "winter" months expecting nice warm sun and a stroll on Ipanema and a cold front blew through with some rain. The temperature wasn't very low but with the humidity and wearing shorts I almosy froze my butt off!!   

not to highjack J's post but this brings up a question. KILN OR AIR DIRED? I have heard that kiln drying deforms the cells in such as way that if you put kiln dried lumber in water it will actually sink instead of float. IT really soaks up the moisture as opposed to air dried lumber. I am sure there are many factors and variables when kiln drying but it is something to think about.

I appreciate the elaboration, guys! Down here in the "sunny" southland, the
humidity never goes lower than 50%...unless the temp stays below freezing
for a few days. The ensuing thaw is SO-O-O soggy....

I'm still constructing my controlled environment, and don't want my early
wood purchases to suffer while they're waiting. (I'll find a shelf for them by
New Year's, I'm sure....)

I suppose I could just run pick up a gross of chopsticks & use them!

Robbie that's a new one on me. Never seen kiln dried wood sink. Most dimension lumber is kiln died and I've seen lots of houses floating downstream on TV this year.
Feel sorry for those folks.

_________________
Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

There is some evidence that Strad built violins from wood that had been cut only a year or two before. So much for 'seasoning'.... ;)

There's kiln drying and kiln drying. If it's done well it should be OK, but how are you going to know? There are those who say that the heat of kiln drying 'sets' resins or starches or something that would normally evaporate or otherwise go away. I'd love to get some documentation on that. I've also read that kiln dried wood is harder to bend. I suspect that's a sign of _improper_ kiln drying, rather than just kiln drying, but again, no documentation.

There are some reasons to think that allowing wood some time to 'season' is good. For one thing, all wood grows with built-in stresses, which can work themselves out over time. Moisture cycling, the normal changes in relative humidity with the seaons, is probably the best way to do this. If you build with wood that has these stresses in it, they could cause warping and cracks, and may also hurt the tone. Good wood probably has less built-in stress, and I suspect the guys sawing it can tell from the way it pinches the blades and all.

Another thing is that there is one component of wood, called hemicellulose, that actually does 'evaporate' over time. It's a polysaccharide that breaks down, again with moisture cycling, into CO2 and H2O, the stuff it was made of. The loss is slow: about 1% of the hemicellulose (which makes up about 25% of the structure of the wood) goes away per decade. The wood gets less dense, of course, and a little less strong, but the denstiy goes down faster, so there's a gain in stiffness/weight raio. Possibly more important: it's the hemicellulose that absorbs water from the air, so as it goes away the wood becomes more stable.

All in all, I'd say that if you hold the wood long enough to acclimate to your shop conditions, which doesn't take long, it should be OK, so long as your shop is 'normal' for where it's going. I, too, once had a southbound guitar end up moving a lot. I built in in January in New England, when high humidity is a dream, and shiped it to the Carolinas. The top popped up a bit, and it took a while for the owner to dry it out. He took the time, though, since he really liked the tone.   

[QUOTE=Bobc] Robbie that's a new one on me. Never seen kiln dried wood sink. Most dimension lumber is kiln died and I've seen lots of houses floating downstream on TV this year.
Feel sorry for those folks.[/QUOTE]

Haha. I heard this from a very reputable violin builder this week. It sounded interesting but I don't know for sure that the info is true.

One of my supplier had some Claro Walnut which when cut into guitar set all warped like crazy and was very brittle by walnut standards.

He described this to me as Case Hardening, and said it was because the wood had been kilned too fast.

I tend to go for air dried materials when I can, because whilst I have not heard of Kiln dried material not floating, I have seen evidence that it becomes very hungry for moisture, maybe it is just over dry and returning to normal levels.

    having been around the sawmill business a while I learned a few things. There are a few different type of kilns and different stages of drying and operating a kiln.
   The first step took about 1 week to 10 days. This is when the "easy water" is taken off. The wood is stickered and air is circulated with a dehumidifier drying the air.
   You would be amazed at the amount of water that can decant in this amount of time. You cannont dry the wood very fast or you will cause checking .
   Once the moisture went into the teens you started the heating process. This would take about 3 weeks to bring the wood to 6-8%
    This is with a standard heat kiln. They now have solar and RF kilns. If the wood is overheated and overdried this will cause the case hardening.
   Yes kiln drying will deform and colapse the cells but it will not make wood sink. Your wood will in fact be ligher and more controllable. Kiln dried wood is more stable than air dried. Air dried will get to maybe 11-12% at best. Kiln dried can be pulled to 6-8%
    The important thing is to "sticker the wood. If I had to make a choice spruce would be my first choice or poplar for stickers.
      As was pointed out by Al , it is the stabelization of the chemicals and teh cell structure in the wood that will be done by kilning. The water issue is a constant flux as wood is hydroscopic and will absorb and release water as to the conditions. Woods like Rosewood and cocobolo take more time to stablilize without a kiln.

Kinda raises the question of if wood floats then why are there so many wooden ships (or houses) at the bottom of bodies of water?

-Rick

[QUOTE=Alan Carruth] There is some evidence that Strad built violins from wood that had been cut only a year or two before. So much for 'seasoning'.... ;)

There's kiln drying and kiln drying. If it's done well it should be OK, but how are you going to know? There are those who say that the heat of kiln drying 'sets' resins or starches or something that would normally evaporate or otherwise go away. I'd love to get some documentation on that. I've also read that kiln dried wood is harder to bend. I suspect that's a sign of _improper_ kiln drying, rather than just kiln drying, but again, no documentation.

There are some reasons to think that allowing wood some time to 'season' is good. For one thing, all wood grows with built-in stresses, which can work themselves out over time. Moisture cycling, the normal changes in relative humidity with the seaons, is probably the best way to do this. If you build with wood that has these stresses in it, they could cause warping and cracks, and may also hurt the tone. Good wood probably has less built-in stress, and I suspect the guys sawing it can tell from the way it pinches the blades and all.

Another thing is that there is one component of wood, called hemicellulose, that actually does 'evaporate' over time. It's a polysaccharide that breaks down, again with moisture cycling, into CO2 and H2O, the stuff it was made of. The loss is slow: about 1% of the hemicellulose (which makes up about 25% of the structure of the wood) goes away per decade. The wood gets less dense, of course, and a little less strong, but the denstiy goes down faster, so there's a gain in stiffness/weight raio. Possibly more important: it's the hemicellulose that absorbs water from the air, so as it goes away the wood becomes more stable.

All in all, I'd say that if you hold the wood long enough to acclimate to your shop conditions, which doesn't take long, it should be OK, so long as your shop is 'normal' for where it's going. I, too, once had a southbound guitar end up moving a lot. I built in in January in New England, when high humidity is a dream, and shiped it to the Carolinas. The top popped up a bit, and it took a while for the owner to dry it out. He took the time, though, since he really liked the tone.   [/QUOTE]

Alan, this is interesting stuff. What is/are your source(s) for the info so I can read more?

Thanks, Steve

Steve:

The information about hemicellulose degradation came from an article by Ephriam Segerman in the 'Journal' of the Catgut Acoustical Society, Vol4, No3 (Series II) May, '01, pp. 5-9.

I learned a lot about built-in stresses from: "Growth Stresses and Strains in Trees" by Robert Archer, Springer-Verlag 1987, ISBN 3-540-16406-5.

Hoadly also talks some about this in his 'Understanding Wood', I'm told: I don't have that.

The dendrochronology stuff is still being done on old master violins, and there seems to be plenty of room for arguments.

The stuff on kiln drying and bending was in an article in Fine Woodworking, on making Morris chairs, iirc. Can't give you the issue offhand.

Oh yeah, almost forgot:
Once you move wood into your shop it will gain or lose moisture until it's in equilibrium with whatever the R.H. there is. So far as I know, the equilibrium moisture content of kiln-dried and air-dried wood is the same in a given R.H. It may not be possible to get air dried wood much below 12% M.C. when it's outdors, but if you bring it into the shop where the R,.H. is lower it should drop to 6-8% or whatever is appropriate. Anybody got some data on that?Alan Carruth38694.7047569444

   I used to build furniture before doing this. I liked to do period stuff and would dry my own. The best I could do was when I stacked the wood in my rafters in my old shop.
   I had it stickered and with 24 hr fan. During the summer it would be heated to about 125 degrees. I could get this down to 8% and that was as low as I ever got it.
   Most of my air dried seemed to stay at the 10% range.
I used poplar pine and red Oak. It took a year to dry. ALot also depends on your location. the drier your environment the bettern Penna gets humdid in aug and dry as a bone in winter
john hall

[QUOTE=Alan Carruth]
There are those who say that the heat of kiln drying 'sets' resins or starches or something that would normally evaporate or otherwise go away. I'd love to get some documentation on that. [/QUOTE]

Alan, conifer species including pine, spruce, larch and Doug fir have resin canals (hardwoods do not as a rule although some have gum ducts)in the sapwood. Kiln temps above 175F in schedules do indeed "set" the resins in conifers. This is not to say that a spruce board with a cubic inch pitch pocket will not remain fluid in the process, but resins are contained in the resin canals and emerge as tiny drops over time when air dried only. We must remember that commercial conversion and drying of wood is not aimed at guitar makers, but furniture, siding and panel makers. Conifers selected for stringed instrument use are given a special place in the selection process and material with obvious "resin defects" are rejected for the most part. Resins will migrate to a surface and bleed thru paint overtime unless pre-set. White pines and sugar pines are bad for this. It's true that resins will harden on their own, but one must think in terms of years and years for the change to happen. "Setting" the resin in a kiln helps to minimize the bleedout problem.

While Hoadley does describe this need and process for setting resins in his "Understanding Wood" book it is also pretty well covered in descriptions of kiln proceses used for decades. I'm pretty sure you would have no problem extracting this data from the USFS Lab and research documents. Hope this might help.

"Seasoning" is an old, old term used mostly in the fire wood business of old. Wood allowed to sit stacked open thru the seasons (summer, fall, winter and spring) is considered to be seasoned or dry.