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Humidity is rising
enalnitram (Martin Lane)

Total Topics: 47
Total Posts: 338
So some of you may already be acquianted with my humidity issues. I glued on some bracing when the humidity was probably too high, and then when my house dried out in January, the top and back went concave.

Well, I removed all the bracing. I put together a little psychrometer, in order to get an accurate measurement of relative humidity. I made new bracing, and I glued it on in drier conditions. And I started building another guitar.

I've got top and back bracing glued on both guitars now. And I've been keeping my eye on humidity. It's been steadily rising here lately indoors, and I thought I might have a few weeks before things got above 40-something percent here in my basement. But it happened today! This week with temps in the 40's and even a little bit in the low 50's, I've got 50% RH in my basement now. I really thought I had more time! My window is over. 8^(

What to do? I'm thinking of buying a dehumidifier. I have a basement which is finished, but has a concrete floor. Can I build down here in the summer if I seal the floor and run a dehumidifier? Anybody here do that?

Mar 11, 10 | 6:56 pm

Total Topics: 29
Total Posts: 448
I had a house with an unfinished basement and ran a dehumidifier in it. It kept the humidity under control. However, I was not building guitars at the time and I did not monitor it except with a thermometer/ humidity combo gauge. Probably not extremely accurate, but it did read below 50% even in the summer in New York City. Thats not bad. Oh...the basement was about 1200 square feet and the dehumidifier was rated for no more than 350 sq. ft. or so by the manufacturer.
I had no walls down there, but I bet if I did have a small room with the dehumidifier it would have been fine.

Mar 11, 10 | 7:30 pm

Total Topics: 4
Total Posts: 74
Your in grand rapids, right? I'm across the lake near milwaukee. My tops dopped too. I was already having neck angle problems even though I sloped my body. I'm worried the bridge ht. will change in the summer also. When I got in to the seven circles of hell, guitarmaking, I didn't think I had to build a humidity control basement. Your topps must have really dropped for you to do all that work. I made mine 28' rad. and was going to try 40' like ken has on his site. But after reading your story ,I'll have to think about it. My tops didn't drop in like yours , in fact it helped my neck angle problem, I needed more ht. But now if I finish will the action change in summer? just thinking is'nt this fun. Dave L.

Mar 12, 10 | 6:26 am
Ken Cierp

Total Topics: 58
Total Posts: 2262
The movement of the top contour and the relationship to the neck set is the same no matter what brace contour you use. If the top shrinks X amount the bridge will lower X amount and change the fingerboard plane relationship. Taylor uses "flat" bracing "no contour" on its very best guitars --- there is an option however of a 65' radius said to increase treble response.


Kennth Michael Guitars est. 1978

Mar 12, 10 | 6:40 am
enalnitram (Martin Lane)

Total Topics: 47
Total Posts: 332
Dave, yep I'm in Grand Rapids. We had snow in November, but it hadn't been cold for long. I just wasn't aware of how critical this thing was, and of how much more I needed to be paying attention. Yet another newbie lesson. I think it must've been 60-65% RH down there when I glued the bracing on my top and back. About 6 weeks later, and it was probably around 15-20%. I'm not even sure. Now I'm vigilant. We have to be.

Thanks for the advice, Tony. I have a neighbor that is going to loan me his large dehumidifier, so I can see how that goes, before I buy one. I'm going to let it run for a few days and if things are stable for a week, then I plan to resume gluing. The next thing I need to do is to glue tops and backs to rims. All that is on hold 'til I get this under control.

Mar 12, 10 | 7:06 am

Total Topics: 4
Total Posts: 74
I didn't mean to say anything bad about 40' rad. I was walking my dog and was thinking, if there was something really wrong wt. 40' rad. Ken Cierp would'nt use it. I just like to say I've learned more from you and your site than anyone else on this forum. So OK Ill watch my humity on the next one, after I finish these two. Thanks for more info Ken and good luck Grand Rapids.

Mar 13, 10 | 5:00 am
Ken Cierp

Total Topics: 58
Total Posts: 2262
Hi Dave I did not take it that way -- not to worry -- there's just a lot of info out there regarding the purpose/benefit or even the need top contour -- some/most? of which is not scientically founded. One of my personal beliefs is that a domed plate used to cover a given area is slightly larger than a flat plate therfore if the plate shrinks to the size of the flat plane area it is a "little" less likely to crack.

A note about dehumidifying a larger area -- I leave my big air cleaner/filter running most of the time to keep the air circulating, my guess is that this helps dry the air as well by averaging what goes through the dehumidifier -- so a fan at the opposite end of the room my be a good idea.


Kenneth Michael Guitars est. 1978

Mar 13, 10 | 5:19 am

Total Topics: 34
Total Posts: 165
I've enclosed a small - 100 sq ft? - portion of my garage to use as a build/glue area. I bought a 40 pt dehumidifier and many days I have to empty it twice. I have it set at 45-50% and it works well - fairly quiet, shuts off automatically when it is full. I believe I paid $149 online. Soleus Air is the brand; it got good reviews.
I have a concrete floor, btw.

Mar 13, 10 | 6:49 am

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