Official Luthiers Forum!

Hello All,

I know this subject has been discussed so many times, but, if you will indulge me, I’d like to ask,
to anyone who would be interested, about the humidity issue once again.

I air dried my own 4/4 lumber about 5 years ago on my property to be used in the building of my
house. It was southern yellow pine which was used as flooring, and red oak which was used to
build cabinets. It air dried for approximately 1.5 years. Before sending it to the planner, we tested
it for moisture content. It ranged from 12%-17%. The widely acceptable moisture content of
wood to be used in a house, is generally around 6%-8%. So, we knew what would happen after it
was installed. After about a year, the flooring developed a little cupping, and spaces between the
boards. Same for the oak, you can see cracks, and spaces on the cabinets. This is what we were
looking for though. We wanted a new house that looked old.

OK, I had to say that first, because I have a guitar, that I’ve owned for close to 28 years. It is a
“Sigma” and it was made in Korea. On the peghead, it reads, “Sigma Guitars est. 1970".
The guitar looks and plays just as good now as it did when I first bought it. This guitar has gone
from Florida to Spain, Greece, Africa, back to Florida, and finally where it lives now, Georgia.
The guitar spends all of it’s time in a case, when not being played. And, I should say it doesn’t get
played very often. At first I thought that the case was protecting it from changes in humidity.
Now, I think that, it makes little difference in the big scheme of things. I placed a hygrometer
inside the guitar though the sound hole, and quickly closed the case. Some time later, I checked
the reading, and to my surprise! It was only 5% lower than the room it lives in, where the room is
usually around 60%.

Q1. Why is the wood in my house, and like so many other houses that I’ve built, so greatly
affected by the heating and cooling system, but, not my guitar?

Q2. Is an air-conditioned environment the perfect environment for a guitar?

Q3. If “Martin Guitars” are sold around the world, why don’t they have issues, or do they?

I could think of a lot more questions, but, I guess this is a good start!

Robert

_________________
Everything has beauty, But, not everyone see's it!

Robert,

Here is my view/understanding on wood stability. Once wood is harvested, it starts a slow and often significant drying and shrinking process. As time goes by, and the moisture exits, it will shrink, twist, bow, and split until it finally reaches some sort of equilibrium. It really takes quite some time for this to happen.  While this is going on, there are stresses being imposed into the wood as it is continually shrinking and tightening up.  That`s one of the reasons for the seemingly wacky ways wood behaves when we cut it closer to the dimensions we want. Ever notice that when you rip a piece on the table saw, it sometimes pinches the blade or the kerf opens up? That is the stresses being released from the curing/drying process.

Shaker furniture and barns use this to an advantage when they use the peg and hole joinery, and mortise and tennon joints. The makers know that this shrinking and drawing will tighten up their joints (not to be confused with age creeping up on our bodies as we age).

When I was restoring pianos, I read that the Baldwin company only used wood that was aged at least ten years for their soundboards and cases. This is one of the reasons that older pianos often, but not always have a split in the sounboard, thus depriciating the value and sound.

When moisture and temprature are introduced to the picture again, that`s where we try to make the best prediction that we can about just what is going to happen, and try to find that happy medium where the warping, twisting and so forth are going to happen.

I`m sure the pros will be along in awhile, but there`s my two cents.

Coe

_________________
Give me 50 cents worth of regular.
Check my oil too, if you don`t mind,,,

All the sigmas I have seen are laminated back and sides .. not sure if the tops are solid. But, if the guitar was built in lower RH, it will survive a long time in slightly higher RH environments ...

_________________
Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

1) your wet house wood would have been subject to the drying affects of your heating and refrigerated airconditioning sysems.

probably the most common type of air conditioning used in dry climates is evaporative and it actually will humidify the inside air helping to maintain the rh at a healthy level for instruments, and humans too.

2) as tony said, plywood is not as susceptible to the vargaries of rh as are solid woods. and a properly constructed solid wood guitar will be affected if you let the winter heating system dry things out too much.

3) and martin's solid wood guitars have issues with humidity just like any other solid wood guitar, or violin or bass or cello, etc. following taylor's lead, martin has for some time had an area of their web site devoted to proper care and humidity control.

Thanks All,

Sorry about not getting back sooner, been a little busy.

Hesh, the answer to your question is Yes, Yes, Yes!!!
So, if I get the gist here, high humidity = OK! Real low humidity = Not OK! Got Ya!

Coe, I have noticed the stress releasing action of wood when it’s ripped.

Tony, I have closely inspected my guitar, and I can’t make a clear judgement to whether it is
laminated, or not. Could you advise me as to what to look for?

Michael, we have a heating & cooling system that removes moisture from the air inside our house.
It is equipped with a condensation pump. Interestingly enough, we have a hydrometer in our house,
and it stays close to what it is outside. Of course, it goes up and down respectively. I will do some
more research, and visit Martin’s website.

Another question;

When building a guitar for a client, should one try to build that guitar in an RH, as close to the
RH of the area where the guitar will be sent?

Robert

_________________
Everything has beauty, But, not everyone see's it!

First off a sigma isn't a true martin . They are no longer being made. THe first ones were made in Korea and were moved to Indonesia. They are laminated. The ones with a solid top are ST designated IE DR1ST. As for the wood movement many gave you a very good expaination.
   ALso there is a difference between air dried and kiln dried. Wood takes years to "air dry". The best way to air dry is to sticker wood and have air flow over it. Just stacking it , even if stickered , the moisture content will ary greatly even in the same board.
   Also your guitar has a finish on it and was most likely kilned ( more stable than air )
So there is no simple answer to your question. I have this analagy to help you understand what is happening.
Wood cells will expand and contract with RH changes. They will move across the cell not along it so that will explain the opening and closing of the cracks.
    Another thing is the wood on the quitar is quartered and this is the most stable way to use wood. Face sawn or rift cut will move up to 1/4 inch per foot.
john hall

no, high humidity is not good!!!!!

build with wet wood and the guitar will likely crack up when kept in a dry house in the winter, or if it goes to an area of dry climate.

by building at a medium level of rh the wood will have a limited capacity to both take on water in a wet environment and give it up in a dry one, but within limits.

go beyond the limits and things can go south quickly.

if the guitar takes on too much moisture the top will rise and the action can become difficult or virtually unplayable.

if it gets too dry the top will sink, even becoming concave, buzzing ensues and cracks will follow.

taylor was probably the first factory to begin trying to educate owners on the pitfalls of humidity fluctuations and how to avoid them. since then other makers have followed suit.

it was not uncommon in the past for players to have two saddles, a low summer saddle and a tall winter saddle.

it is impossible to keep the humidity level of an instrument totally constant unless it is built and never removed from a perfectly rh controlled environment.

when i was involved in the construction of the australian national gallery i always took wonder at the climate control and monitoring system that could record and react to the changes of temperature and rh resulting when a person walked through one of the exhibition halls, vast open spaces with ceilings which were probably 20' or more. that would be an ideal environmrnt for an instrument to be built and live.     

however i don't think many of ours will will be so fortunate. but what is possible is to build at medium rh and subsequently to limit the rh fluctuations of the instrument to a relatively narrow range wherein the instrument will retain its playability as well as its structural integrity.

Here in Florida we have real High humidity, 100% sometimes! But on any given day it's between 70-90% most of the year. I put a top (that one of our suppliers gave to me as a gift... it was a very inexpensive top) out side ( I use part of my outside, covered deck/lanai as a dust work area) and let it sit for a day...curled up like a potatoe chip. That should answer any question about hummidity. I also have a hard time convincing my customers not to go to the beach or park for too long a time with their guitars exposed. It usually only takes one time for them to learn not to do that again.

_________________
Dave Bland

remember...

"If it doesn't play in tune...it's just pretty wood"

p.s. I sell electrics that I recommed specifically for high hummidity areas like the beach. Basically they are ash bodies, Maple necks with a bone nut. I bought several dozen from a large wharehouser, real cheap, So I sell them real cheap ($250 all setup with frets dressed) Yes they get affected by the hummidity but because they are solid body electrics with pretty stable necks people leave them in their hot cars and they don't get ruined like an acoustic would. I sold out those and now am buying plywood bodied units, again with maple necks and they are holding up equally as well. maybe the poly finish helps too.

_________________
Dave Bland

remember...

"If it doesn't play in tune...it's just pretty wood"

[QUOTE=Hesh1956] 

Another approach is to tell the client to move.......    And I know just the perfect home builder to build their new home......... [/QUOTE]

Hesh, thats a good idea, build them a guitar and a house to put it in,

I agree that you need to build in reasonable PH conditions. I don't build over 55% or under 40%. YOu also need the wood down to 6-7% for best results.
As pointed out wet wood when building is nothing more than a disaster waiting to happen
john hall

I have a pretty good collection of handmade and vintage guitars all of which I keep in my home. Humidity is high in my area but certainly with the A/C and Heat things stabilize. I do live in an "open window" let whatever is out in 4-5 months per year. Interesting however, I travel regularly with one or more guitars to a variety of different climates and have never had a problem with any of my guitars in changing humidity and climates even for extended times. Just carried one of my handmades in a case in the back of my pick-up from balmy East Texas (70% RH) to the high arid desert of Taos, New Mexico with very little humidity at all.

I think guitars are alot like horses, when you fret over them to much and worry all the time and try to keep them in stalls in all the right conditions, they always get sick and die or become lame and crippled. On the other hand if you turn a horse out in the pastures and let it acclimate and live like a horse it never gives you any trouble.

I build and own more pasture guitars

Maybe I am just lucky...........

Mike

I recently bought a 3 inch billet of sitka spruce from a supplier in BC Canada. It has sit in the house since I bought it because my new shop isnt quite ready and I didnt want it damaged with the construction.

Anyway, this billet was supposed to have been aged for over 4 years. Since it has been sitting here in my living room, it has devloped several checks in the wood (cracks) that generally follow the line I would cut if I were to try to cut it into thin tops. I know this is due to humidity as we are having a severe drought here in this part of Florida and the RH is down to around 25%.

Since I bought this billet cheap and am planning on using it for bracewood anyway, its no big deal.

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Reguards,

Ken H

Hesh, that’s very funny! Ha Ha Ha!!!

Seriously though, it would be the extreme RH conditions of a particular area, to build for a client
that I was referring to. Moreover, I would expect that to be the exception rather than the rule, and
I have to wonder, if anyone has ever attempted to do what I have suggested anyway!

It does appear that it would not be a concern, if one were to build in a medium range RH, 45%-55%.
Then send the guitar to a higher range of RH. (Within reasonable limits, of course)
However, building in the medium range RH, then sending the guitar to much lower range RH,
could be devastating.

The question is; Would it be worthwhile, to make the effort, to build a guitar, as close as possible,
to the average RH range, to which the guitar will live?

Then, on the other hand! We have Mike Spencer’s post,(Thank you Mike) which I feel illustrates
perfectly, and validates the inquiry of this topic. “Is Humidity Really An Issue”?
Here we have a gentleman guitar builder with real guitars, and real situations, dealing with different
RH conditions. You can hash out all the numbers, and data you want. However, experience will
always be the best teacher!

So, where does this leave us my friends? The only thing I’m convinced of, is that a guitar built in a
medium RH range, then sent to a very low RH range, like 15%, and then left in that environment
unattended, for at least several days, (how many days? Don’t know) will have adverse effects.
But, I get the feeling that very few people would allow this to happen, and I also feel, that it doesn’t
take a whole lot of effort to keep this from happening.

Could be wrong though! Been wrong before! Lets see, I think it was back in the early 70's

Robert

_________________
Everything has beauty, But, not everyone see's it!

the build it in medium rh and the guitar then ending up in a 15% rh situation happens very, very frequently, and it does not require transportation to a distant dry climate. as soon as it leaves the shop and goes home to the over heated living room and is left on a guitar stand, or worse, hung on the wall, for all to admire as room decor or wall art the damage begins. and when you tell the client they are destroying their guitar they stare blankly, or look agrieved.

winter rh inside a forced air heated house, even in the southeast, can get down into the single digits. in the northern climes it is very, very common.

the reverse situation, going to a humid environment, may not cause catastrophic structural damage, but can make the instrument unpleasant or virtually impossible to play, and in my opinion lead to the need for premature neck resets.

that a particular owner has not had an unfortunate experience is not a refutation of the need for rh control. It only means he was lucky.

Got a guitar into the shop last week .. ziricote, the owner had no humidifer all winter long here in canada ... bad,bad things happened to the back. It was built in 43-44 % RH, and for a few weeks lived most likely below 15%. Things are back to where they should be now with the RH at about 50 around here, but the scars are still there.

Most builders up here in the know wouldnt chance building (bracing and body assembly at least) over 45, most are staying around 40. It makes a huge difference when winter arrives, because almost no one I know keeps their house as humid as I do in those months.

I have sent more than one client home with a guitar after they complain about strings buzzing in February to keep the guitar in the bathroom after a hot shower and get some serious humidity into it, with no room fan ... funny how I never hear from them again after that ..

_________________
Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"