Humidity

[Braindead]

I am a CF guitar lover but somehow I have acquired several of the wooden beasties. I never considered humidity until recently I traded for a wooden parlor guitar that I really like. It had some problems with the sound board but after three days of hydration, it looks pretty good.

I bought a hydrometer and I want to take better care of all these guitars. The question is what is a good humidity range?

[rlb9682]

Usually 35%-50% is a good range. I've seen builder recommended ratios of either that or 40%-55%.

But in general; I'd say 35%-55%.

[charles Tauber]

The target is the same relative humidity as that at which the instrument was made. Most makers maintain the construction environment in the range of 40 to 45% RH.

As the instrument moves away from that value, the wooden materials from which it is made either expand or contract. As the humidity rises above that value, the instrument swells and the action rises. As the humidity drops below that value, the instrument shrinks and the action lowers. Some find that the tone of the instrument changes, particularly as the humidity rises.

At some amount of shrinkage, the body, being constrained all around its edges, can't shrink any further and parts split - top and back, usually. What amount of shrinkage an instrument can sustain before splitting varies with the individual instrument. In short, the greater the humidity drops below the value at which an instrument was made the greater the probability it will crack. Some instruments split at fairly high humidity levels - 30% - while others can withstand much lower humidity levels. You don't know until after it splits how low is too low. If you maintain humidity levels near the 40 to 45% at which most guitars are made, you minimize the chances of humidity-related damage.

[Braindead]

I just walked into the room where I keep and play my guitars. The hydrometer reads 75.7 degrees F and the humidity reads 63%.

It looks like I have some work to do.

Thanks, everyone!

[PWE]

Originally Posted by charles Tauber

The target is the same relative humidity as that at which the instrument was made. Most makers maintain the construction environment in the range of 40 to 45% RH.

As the instrument moves away from that value, the wooden materials from which it is made either expand or contract. As the humidity rises above that value, the instrument swells and the action rises. As the humidity drops below that value, the instrument shrinks and the action lowers. Some find that the tone of the instrument changes, particularly as the humidity rises.

At some amount of shrinkage, the body, being constrained all around its edges, can't shrink any further and parts split - top and back, usually. What amount of shrinkage an instrument can sustain before splitting varies with the individual instrument. In short, the greater the humidity drops below the value at which an instrument was made the greater the probability it will crack. Some instruments split at fairly high humidity levels - 30% - while others can withstand much lower humidity levels. You don't know until after it splits how low is too low. If you maintain humidity levels near the 40 to 45% at which most guitars are made, you minimize the chances of humidity-related damage.

I agree with the excellent quote above with a slight expansion of the range of 40 to 50%. Based on your location in Georgia and your present 63% humidity reading, it appears to me you are in need of a room dehumidifier to achieve the ideal levels for your acoustic guitars.

[charles Tauber]

Originally Posted by PWE

I agree with the excellent quote above with a slight expansion of the range of 40 to 50%. Based on your location in Georgia and your present 63% humidity reading, it appears to me you are in need of a room dehumidifier to achieve the ideal levels for your acoustic guitars.

Thank you, but I purposely did not state a range at which one ought to maintain one's instrument. Instead, I attempted to, briefly, explain what to expect if one deviates from the humidity level at which the instrument was made. Ideally, rather than blindly follow some published range, one can, based upon their own situation, climate, etc., decided for oneself what sort of maintenance one wants to perform.

For example, for me, unless I found the sound of the instrument was untenably altered at 63% RH, or its playability sufficiently altered, I wouldn't bother with lowering the humidity. Humidity in the 60's isn't going to cause any damage to the instrument. Low humidity is a different story altogether. Controlling humidity while making a guitar is yet a different story.

[ClaptonWannabe2]

Originally Posted by Braindead

I just walked into the room where I keep and play my guitars. The hydrometer reads 75.7 degrees F and the humidity reads 63%.

It looks like I have some work to do.

Thanks, everyone!

Keep in mind location of the meter. I near panicked the other day when mine read 36% RH in my room. It was sitting under a lamp. the light dried that little air column out I guess.

Under fans, too far from window, too close to a window. All can make that number swing wildly. You may just have to run your AC more and live with socks and slippers in the summertime.

[Quickstep192]

Also keep in mind the accuracy of your hygrometer. I’ve had several that were so far off it wasn’t funny. I’m told that most are only accurate within a certain range. For example, cigar humidor hygrometers are accurate at the high end of the range, but can be way off in the middle of the range.

[fazool]

Originally Posted by Quickstep192

Also keep in mind the accuracy of your hygrometer....
.

Since you are new to humidity concerns, I hope this is helpful

[Braindead]

Originally Posted by fazool

Since you are new to humidity concerns, I hope this is helpful

Extremely helpful. Now, I have to locate a "pro" hydrometer to compare mine with.

Thanks all!

[Braindead]

Originally Posted by fazool

Since you are new to humidity concerns, I hope this is helpful

Extremely helpful. Now, I have to locate a "pro" hydrometer to compare mine with.

Thanks all!

[Quickstep192]

I have this one.

http://www.theweatherstore.com/nicedihy.html

[C_Becker]

I'd be more worried about the lower end of the spectrum to be honest.
63 % rH wouldn't worry me, 36% would.
Anything below 40 I start putting those little humidifiers in my cases.

[Braindead]

Originally Posted by Quickstep192

I have this one.

http://www.theweatherstore.com/nicedihy.html

I am sure it is more trustworthy than what I bought but a question comes to mind.
Does a hydrometer maintain it's factory calibration or it that subject to the original quality?

[charles Tauber]

Originally Posted by Braindead

I am sure it is more trustworthy than what I bought but a question comes to mind.
Does a hydrometer maintain it's factory calibration or it that subject to the original quality?

A hydrometer is an instrument for measuring relative density of fluids. A hygrometer is an instrument for measuring relative humidity.

Hygrometers, like many other measuring instruments can drift over time and might require recalibration. However, don't go crazy about this. If you aren't doing laboratory work, making instruments or some other humidity-critical process, all you need is an instrument that tells you the relative humidity to within about +/- 5%.

I have literally bought - and tested - hygrometers from $1.99 to $150. The $1.99 I bought and tested works just fine for this purpose and can be sufficiently accurate. One trick is to buy one from a shelf where there are many. Chose one that reads the same as the others: some will vary widely from the average. That doesn't guarantee accuracy, but increases the likelihood that it does. It doesn't need to be "laboratory quality" and doesn't need to be expensive.

I have several inexpensive hygrometers that are as accurate now as they were 30 years ago when I bought them. (Yes, I check them annually.) That doesn't mean that every hygrometer will be, but one needn't stay up late nights worrying about it. Your guitar is a hygrometer. Learn how to read it and pay attention to what it tells you. As you learn to do this, rely on the hygrometer to help.

Making guitars is a different matter altogether, where much more consistency and accuracy is required.