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| How dry is too dry? http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=19871 |
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| Author: | mtracz [ Tue Dec 02, 2008 7:09 pm ] |
| Post subject: | How dry is too dry? |
My basement shop is at about 39% relative humidity and 61*F. Is has done wonders warping a top and back I'm trying to get ready to glue up. I glued the braces on at around 45%. So the question remains is 39% to low to continue building? And if not how do you recommend getting my basement up to the right level? Thanks, Mike |
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| Author: | Rod True [ Tue Dec 02, 2008 7:37 pm ] |
| Post subject: | Re: How dry is too dry? |
On it's own I don't think 39% RH is to low to build to, but you need to keep it there. If you glued on the braces at 45% then you need to bring the RH in your basement up to 45% before you glue it to the body. Consistency is very important. Get a humidifier to bring the RH up. Also get a couple of hygrometers or make a sling psychrometer so you can accurately monitor you RH. |
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| Author: | Mark Groza [ Tue Dec 02, 2008 7:38 pm ] |
| Post subject: | Re: How dry is too dry? |
Sounds like your humidity changed on you since doing the braces.I like to keep it steady while building the box.A humidifyer might help your situation.I try to keep it above 40% and less that 50% and real steady while building the box to keep it from moving around while doing the build. 
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| Author: | Hesh [ Tue Dec 02, 2008 7:47 pm ] |
| Post subject: | Re: How dry is too dry? |
Yep what Mark and Rod said. My shop is currently at 45% RH with a recently calibrated Aberon hygrometer and 74 degrees F........  Me - I'm not proud....... I recently moved with a half built guitar and I made it a huge point to seal up the box before exposing it to no humidity control for the next 6 months. So Mark has a good point about the box needing to be built in stable humidity with acclimated materials. |
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| Author: | Alexandru Marian [ Tue Dec 02, 2008 7:52 pm ] |
| Post subject: | Re: How dry is too dry? |
Make sure it won't go even lower to about 35. That will not only wipe out all doming, but will curl it up the other way around and backbow the braces. Looks pretty scary. It happened to me twice, once in the summer when hit by a drought/heat wave, and a couple weeks ago because of a winter storm. The constant strong wind accelerates air exchange with the outdoor. In both cases I had just finished bracing within 45 to 50%, and due to my excellent good fortunes, within hours it went down to 35 even 30. A few hours of exposure are enough to sort of imprint a memory, because even a couple days back in the original humidity were not fixing the shape. In the first case I had to shave down some braces and reglue in the dish, and this second time I got lucky and fixed it by keeping it about 1 day in the bathroom at 60-65%. |
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| Author: | mtracz [ Wed Dec 03, 2008 7:25 am ] |
| Post subject: | Re: How dry is too dry? |
thanks everyone! looks like I'm going to have to bring the humidity up before I close the box up. I put the top and back in a garbage bag with a moist paper towel and it seems to have fixed them a bit. I'll keep my fingers crossed... Thanks again! _Mike |
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