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Humidity strikes again
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10102&t=13374		 Page 1 of 2
Author:  Alexandru Marian [ Fri Aug 24, 2007 8:58 pm ]
Post subject: 
I had a top done, after of a lot of hard work bracing and voicing it I was so pleased with it that i decided not to put it on the topless box I had at hand, but rather to start another build from scratch.  So i started to carve a new neck, and in the mean while a heat wave struck.  It got so hot in here that I was sweating a lot while carving that neck, also drunk a lot of water. Never imagined to me that the humidity is probably rocketing. At the end of the day, again pleased with a very nice neck from the first attempt, I had a look at the top to check the 12fret thickness and make the neck rebate.   CURLED.  The face turned concave on each half.  I was ready to cry to be honest... As always, when things go smooth and nice in a row, they surely must go utterly wrong soon .

I moved it to another room that has a more pleasant air (at least it's not hot in there), and put it in a dish with a couple books on it.   Now it's time to pray... 



Author:  robertD [ Fri Aug 24, 2007 10:13 pm ]
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Hi Alex,

I feel your pain. The woe’s of humidity can weigh you down!

The same thing happened to me, and I did just as you did, putting books on the top to attempt a
return to its original shape. I had to leave it weighted down for a week before I got any good
results. Still, the best I could get, was pretty much flat rather than a full desired 25' radius. I
think that can still work, because there is really nothing wrong with a flat top. However, You may
want to leave yours weighted down longer. Could work, you never know till you try.

Robert
Author:  MaxBishop [ Fri Aug 24, 2007 11:14 pm ]
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Alex, I had the same experience with a back that I didn't put glue to the sides right away. I was going to do some experiementing with tap tuning. When next I checked the back it was a very peculiar shape and the cross braces were even bowed! We've had a lot of rain here in the midwest lately and I guess humidity was the culprit.

Good luck,
Max
Author:  Alexandru Marian [ Sat Aug 25, 2007 1:07 am ]
Post subject: 
yes :(..the dehumidifier was on my shopping list for a while :(
Author:  Bruce Dickey [ Sat Aug 25, 2007 2:04 am ]
Post subject: 
Meet Mr. Murphy.

From Murphy's Law, you know the one.

If you return the top to the exact humidity it was when built it should be fine.

Good luck figuring it out.

One of my first determinations was building in airconditioned space. What clued me in was not an event like yours, but rather the sweat dripping off my nose onto the rosewood back. Clear off the kitchen table for this one. And keep parts in plastic bags if not proceeding immediately. That might help.
Author:  Rick Turner [ Sat Aug 25, 2007 4:31 am ]
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It's not that big a deal to keep a closet at a decent humidity level and keep all your parts in there when you're not actually working on them.   I saw a couple of big factories in Japan that did that back in the mid 1970s.   A small dehumidifier (try Sears) and a hygrometer will cost less than the parts that go into one guitar.   We keep humidity under control in our 6000 cubic foot build room with two of the Sears units.
Author:  David Collins [ Sat Aug 25, 2007 5:40 am ]
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Rick's right - given the value of the wood and instruments in a shop,
maintaining a reasonable humidity can seem cheap in relation to
damaged instruments.

I keep the main 700ish square foot working section of my shop at 50%
+/- about 5% year round. I use one main dehumidifier +1 backup, an air
conditioner, and a central humidifier for winter, all of it directly hooked to
the plumbing so aside from filter changes I don't have to worry about
filling and draining. It seems like a big initial investment, but it certainly
saves a lot of headaches over time.

At the very least, a dehumidifier or air conditioned room or closet is a
must have for summer humidity, and a humidified area for winters. For
the current problem at hand, put in in a good environment and hope for
the best. Oddly enough, I would have guessed it has dried since bracing
it. When the top swells from increased moisture content it would typically
cup the other way.
Author:  Alexandru Marian [ Sat Aug 25, 2007 6:04 am ]
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Hmmm.  The summer here is not exactly wet.

When i braced it, the outside humidity was 30 to 50% during day time and 50 to 70 during night. 

Then the heat wave came.

Today, outside, it has been as low as 17%.  At night it won't go over 50.

I keep the  "shop"  ventilated with  the balcony door and window open maybe 23/24.  It gets very hot in here because of sun exposure.

So if it in fact cooked up and dried from the heat, maybe I should damp the concave outer face ?

Or maybe I could wait until tomorrow. Rain and storm is expected...
Author:  Bruce Dickey [ Sat Aug 25, 2007 6:42 am ]
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Like I said. Plastic bag is a stable environment. Wetting the wood directly is probably not best. Do something more along the lines of hydrating a guitar in a case or bag. What do they call the sound hole humidifiers?

I have a couple of Kyser Lifeguard soundhole humidifiers. They are just a thin slice of sponge in a plastic soundhole-shaped holder with holes on the inside. If you had some and put that in a bag it would slowly rehydrate.

Good luck, someone put up a thread recently with hygrometer readings and everything. Anyone remember the heading of that thread?
Author:  David Collins [ Sat Aug 25, 2007 7:09 am ]
Post subject: 
Right, what you really need to do before anything else is set up some sort
of a closet, box, cabinet, or whatever that can be controlled at a stable
50ish% humidity.

If the top comes back in that environment, great. If not, strip the braces
and rebuild it at a good moisture content. If it was indeed braced when it
was too humid then there's really not much you can do. If you over-
humidify it to bring it flat before gluing it on, it will only collapse and/or
crack as a completed guitar. If it stays curled after a few days at 50%
humidity, rebrace it and consider yourself lucky that you found the
problem before it showed up in a completed instrument.

Humidity control and moisture content of woods is absolutely
imperative when building instruments. There is no way to build a
predictably reliable instrument unless this is considered and controlled at
every step of the building process.

Set up a stable storage environment first, then move on from there.
Author:  Blain [ Sat Aug 25, 2007 7:25 am ]
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I would think that different parts of the world are more or less humid than others. Do any of you try to build to a specific humidity depending on what the humidity is like where the customer lives? I'm just curious what the results are if you build a guitar in an approximate 50% humidity environment and the humidity where the customer actually lives is more around the 15% or 85% range.
Author:  jhowell [ Sat Aug 25, 2007 8:03 am ]
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It seems to me that the change in humidity levels is what wreaks havoc with wood. My guess, and it is just that, is that building at 50% plus or minus gives you the most latitiude on where your guitar can end up living without major problems. Even in Michigan, where summer humidity gets right up there, having the heat turned on in the winter will drop the humidity in the house to 20%. I find that AC keeps things under control where I live in the summer, but I supplement humidity with a largish Emerson (rated 2500sf -- works about 1500sf) and a second humidifier for the upstairs bedroom/bathroom. My wife and I have had far fewer winter sinus episodes since leveling the humidity -- a welcome by-product.
Author:  Rick Turner [ Sat Aug 25, 2007 9:10 am ]
Post subject: 
Guitars are better off going from a moderate build humidity level...45% to 50%...to damper than that than going from being built at 55% on up and going drier.   It's the shrinkage that really causes problems; expansion seems less harmful.

So why not build at 25%?   Because that is overkill and does not represent how our clients really live. 47% is sort of the industry standard for Martin, Taylor, etc., and then it is the responsibility of the owner to keep the guitar humidified or dehumidified properly. That's part of responsible guitar ownership.   No companies will honor a warranty on an obviously dried out guitar...and it is obvious when you see it.

The flip side is that if you are not building within that industry standard range, you can expect problems, and you will be responsible for them.
Author:  crazymanmichael [ Sat Aug 25, 2007 10:34 am ]
Post subject: 
remember that guitars do not live outdoors, though they may visit from time to time. they mainly live indoors, though you probably came close to equalling the outdoor rh with your open doors.

if you knew that your guitar would always live in a given environment, forever, you could get away with building for that environment. but most have to cope with a varied range of rh situations, and hence building at a near to median rh is the best alternative.
Author:  James Orr [ Sat Aug 25, 2007 12:06 pm ]
Post subject: 
http://www.bizrate.com/dehumidifiers/products__keyword--
dehumidifer.html

That link will help you compare dehumidifier prices. There is a small one
for $56 right now.

Would someone give a quick run-through of how the process works? Do
you adjust a dial until the humidity level indicated on the hygrometer is
the level you'd prefer? The dehumidifer maintains that number until you
adjust the dial again? Is there more to it than that?
Author:  jhowell [ Sat Aug 25, 2007 12:50 pm ]
Post subject: 
Amen to the water hauling. With gas heat in the winter, the Emerson is going through 6 - 8 gal per day and the bedroon unit about 1 1/2 gal. In winter we usually try to maintain a constant temp of about 68 F, so I haven't has to mess with the settings too much during the day. Our new place has a lot more glass, which is not a good thing in the winter. Its near impossible to get RH above 40% if the glass isn't multi-pane in thickness -- the moisture in the air just condenses out on it. May end up with an aditional unit in the shop this winter.
Author:  James Orr [ Sat Aug 25, 2007 1:18 pm ]
Post subject: 
Thanks, guys. Sorry my messages short today. I've been changing
ball joints on my truck and it's been an all day thing.
Author:  Todd Rose [ Sat Aug 25, 2007 1:34 pm ]
Post subject: 
My dehumidifier sits on a shelf above the utility sink in my shop, and drains directly into the sink. I also have a small air conditioner. Most often I run only the dehumidifier, sometimes the air conditioner, sometimes both.

Then, in the winter, of course, I run a humidifier.

Like many people, I built a two-room shop (in my basement). One room for assembly and wood storage, one for machines. Only the assembly room is humidity controlled. It is well sealed and I have no trouble keeping the humidity within a 5% range.

I also have wood stored in the attic and the garage, which will be brought into the humidity controlled room long before I build with it.
Author:  Todd Rose [ Sat Aug 25, 2007 1:43 pm ]
Post subject: 
BTW, I'm very glad my shop is in the basement. In the winter, it's almost impossible to keep the other floors of my house above 35% RH. Like Jim said, even with good double pane windows, the moisture in the air just condenses on the windows if I try to go any higher than that. I'm not sure if I can fully explain why, but in the basement this is much less of a problem, and I can keep the humidity in the shop where I want it.

Author:  David Collins [ Sat Aug 25, 2007 2:04 pm ]
Post subject: 
One of the best methods of keeping humidity up in a house, room, or shop
is houseplants. Lots and lots of plants. Of course that can be tough in a
basement (where low humidity is less often a problem anyway), but if you
have any windows for sunlight it can make the shop a bit more pleasant as
well.

If your windows are getting condensation and the wall insulation is not ideal,
keep your wood and instruments near the outer walls in the winter time.
While the center of the house may only be 35%, if it's cooler by the walls and
windows the RH will often be at least 15%-20% higher there.
Author:  JohnAbercrombie [ Sat Aug 25, 2007 3:16 pm ]
Post subject: 
[QUOTE=Hesh1956] This I believe acts a a buffer to swings in RH and adds stability.[/QUOTE]
A large stash of lumber will also act as a 'moisture buffer/reservoir' to some extent.
This is a great way to justify your WAS to spouse and family!

Cheers

John
Author:  Jim Watts [ Sat Aug 25, 2007 3:39 pm ]
Post subject: 
[QUOTE=JohnAbercrombie] [QUOTE=Hesh1956] This I believe acts a a buffer to swings in RH and adds stability.[/QUOTE]
A large stash of lumber will also act as a 'moisture buffer/reservoir' to some extent.
This is a great way to justify your WAS to spouse and family!

Cheers

John
[/QUOTE]

Brazilian does particularly well at this
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