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Is this the result of too much humidity or lack of humidity?
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Author:  mburton [ Sun Sep 23, 2012 10:04 pm ]
Post subject:  Is this the result of too much humidity or lack of humidity?
I started trying to build a guitar several years ago, but had to relocate for work, and had to put guitar building on hold for a while. It seems life has settled for a bit, so I'm pulling the equipment out and trying to get back up and running.

When I started I had a humidity controlled room, but the wood has been through various, non-humidity controlled environments for the better part of three years now. The back is bent out of shape while the top looks fine. Can you tell me if the back in the pictures below is bent like this as a result of too much humidity or a is this the result of a lack of humidity?

Image

Image

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Thanks,
Mark
Author:  Spyder [ Sun Sep 23, 2012 11:11 pm ]
Post subject:  Re: Is this the result of too much humidity or lack of humidity?
Can you put the braces on the concave side? If the wood tends to bend that way, is better, in my opinion.

I had this problem with my first two. I don't have a radius dish yet, so I improvised. I cut through the appropriate radius on some 2X4's, which gave me 4 straight clamping cauls with a curved surface. Then I clamped the backs in them, and left them that way in my shop with the dehumidifier running. Seems to have solved the problem.

Good luck,
Author:  David Malicky [ Mon Sep 24, 2012 2:09 am ]
Post subject:  Re: Is this the result of too much humidity or lack of humidity?
mburton wrote:
Can you tell me if the back in the pictures below is bent like this as a result of too much humidity or a is this the result of a lack of humidity?

Probably both... usually 1 side of the wood sees a different humidity than the other, which causes a warp. The humidity-induced effects also interact with whatever the wood wants to do on its own. Then cycle it for a while and the wood is twisted, bowed, etc. If you sticker it with weights, it might straighten out some. Or just thin and brace, as above. Keep the RH controlled (or in a plastic bag, or the radius dish) until assembly.
Author:  Jaybird840 [ Mon Sep 24, 2012 9:46 am ]
Post subject:  Re: Is this the result of too much humidity or lack of humidity?
Hey MBurton,
What part of Austin are you in? I'm southwest if I can ever help out.....
Author:  John Arnold [ Mon Sep 24, 2012 4:49 pm ]
Post subject:  Re: Is this the result of too much humidity or lack of humidity?
Quote:
usually 1 side of the wood sees a different humidity than the other, which causes a warp.

Specifically, the concave side is drier than the other side. If the wood curves the other way when it is flipped over, then it is losing moisture to the surrounding air.
Author:  mburton [ Tue Sep 25, 2012 9:54 am ]
Post subject:  Re: Is this the result of too much humidity or lack of humidity?
Thanks for all of the replies. I was worried that if I braced it as it currently stands that it would distort again after acclimating it back to proper humidity levels. It sounds like that isn't much of a concern, so I'll go ahead and start bracing.

Thanks again,
Mark
Author:  mburton [ Tue Sep 25, 2012 9:55 am ]
Post subject:  Re: Is this the result of too much humidity or lack of humidity?
Jaybird840 wrote:
Hey MBurton,
What part of Austin are you in? I'm southwest if I can ever help out.....


Jaybird,
I very much appreciate the offer. I unfortunately had to move away from Austin for work a couple years ago (and haven't updated my information on here). I'm in Dallas now, but it's good to know there are people relatively close by.

-
Mark
Author:  Mike OMelia [ Tue Sep 25, 2012 4:40 pm ]
Post subject:  Re: Is this the result of too much humidity or lack of humidity?
I can't see your pics right now. But what I would do is take them in the house where you have A/C. Lay them on a flat surface. Lay large heavy weights on them (something big enough and heavy enough to flatten them). They should flatten out in a few days or so. Maybe leave them unpressed for a day or so to let humidity balance out. Then flatten. If that doesn't work, try wiping each side with a damp cloth. Then press.

I would not want to pass them through a sander until they were mostly flat. Nor would I want to glue them to braces until flat.

Mike
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