Official Luthiers Forum!

hey, you have all got me thinking more about r.h.
i had some major flaws because of too high humidity.
now i'm scared to do any glue-ups.
i did anyway yesterday, when it was about 20 percent.
is it as bad when it's low like that?
yes, right?
anyway, any advise on a hydrometer for rh?
i'm chomping at da bit to glue this top on.
alan

20% is low -- but there are some builders, including Froggy Bottom's Michael Millard, who insist on RH that low. At least the guitar isn't likely to crack next time the heat comes on or the owner visits a friend in Phoenix.

Generally speaking meaning I'm not getting into the idea of a guitar built in Arizona that will never (hopefully) leave Arizona most Luthiers that I know and factories that I know of and have info about maintain RH in the 42 - 48ish% range. It's important and IMHO if I could do it all over again I would invest in what ever it takes to stabilize and maintain the proper RH range in my shop before I made an jigs or built any guitars.

There are countless threads in the archives here and probably more instances that we never will hear about of builders ignoring the idea that wood moves with RH swings resulting in concave or potato chipping tops or worse. One of the earliest threads that I remember on the OLF that caused me to go purchase a dehumidifier the very next day was a member who wrote that at 3:00 AM one morning he and his wife were awoken to a very loud cracking sound.... He investigated in his shop and found his second guitar, just recently finished with the 12th coat of nitro and now curing had the back crack and split nearly the entire length because where it was curing was far dryer than were it was built.... Needless to say he was bummed and others like me learned from his pain.

RH is VERY important and so too is a decent, accurate hygrometer that has been calibrated against a standard.

It's good that you are thinking about things such as RH - you will be very glad that you did if your guitars ever get tested by drying out through user error.

StewMac offers a nice little RH indicator. I shopped around quite a bit and this is the only one I could find in the $25 price range that advertised the ability to register RH in 1% increments.

http://www.stewmac.com/shop/Tools/Measu ... 3&xsr=3944

I keep it right in the middle of the shop and reference it all the time. I have a small Fridgidare dehumidifier that I crank on as needs be. I was surprised when that little floor unit was actually capable of holding RH to 40% all summer. It removes 50 pints a day and I have to empty it 1-1/2 times a day on average. My shop is 2400 square feet and is well insulated.

I'll get a humidifier if I need to but I'm basking in the glory of only having spent $250 so far....on something I was thinking would cost WAY more.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

thanks for the replies.
i know rh is important, because i glued up some braces on a top,
it was probably raining outside,
rh 99 percent.
that top dished down so bad.
i finished the git, and didn't care how it came out.
funny thing, it is my favorite sounding acoustic yet.
go figure.
reverse radius? ha!

It didn't take long before I got tired of emptying my dehum bucket every day. A little hole in an outside wall & a short piece of garden hose fixed that in a hurry.
The collector trays on most dehums have a garden hose thread on the bottom.
Sometimes it adds significantly to the electricity bill, but I keep my building & wood storage room at as close to 42% as possible all year round.
My dehum freezes up at anything below 60 degrees F. I have to use an electric heater about 5 months of the year to keep it working properly.

I have two hygrometers in my shop - one from Radio Shack and the other is the Stew-Mac one mentioned above. They converge at about 35% and diverge from each other above and below that. I try to keep things in the 40% range but the truth is (as mentioned above) it's just a hedge against the guitar finding a home in either a drier or wetter climate - a middle ground if you will. I'm in Southeast Texas just North of Houston and the summer (all 9 months of it) is pretty muggy. The window AC/heater unit allows me to control the RH most of the time, but I also have an "auxillary" dehumidifier and humidifier for those days when the weather is far outside the norm. Experience in your environment will be your best guide.

Good luck!
Chuck

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"To live a creative life, we must lose our fear of being wrong"
- Joseph Chilton Pearce