Dehumidifying a guitar

Updated on July 2, 2017 in Instruments & Gear
2 on June 27, 2017

I live where there’s ~70% humidity much of the time. I got a nice dehumidifier for my guitar, rechargeable blue/pink crystals etc. (Eva-dry 333 is the model.) The only place in the case it will fit is under the headstock. I wonder whether it’s dehumidifying only the headstock, or whether it draws air from the rest of the case, specifically from inside the instrument. Thanks, John

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1 on July 2, 2017

Hello John,

It’s probably dehumidifying the whole guitar, but slowly. Perhaps a better place to put it would be in the little accessory box in the case, with a few holes drilled in the lid.

Does it come with a humidity gauge? The real danger to your guitar is low humidity. The top wood in particular changes dimension a lot with humidity changes, and cracks ensue when the humidity gets much lower than the humidity at which the guitar was assembled. Received wisdom is that the guitar should be put together at around 45% relative humidity, as a good compromise.

There is a guitar case humidity control device available—I don’t have a link—that uses a salt that maintains humidity at a good level. It removes moisture when the humidity rises, and adds moisture when the humidity falls. It’s just the physical characteristic of the salt. A student of mine that runs a calibration lab uses the stuff to calibrate humidity gauges!

Cheers,

Brian

on July 2, 2017

Hi Brian,

 

> It’s probably dehumidifying the whole guitar, but slowly.

 

That was my guess, since people put these things in closets and find they dehumidify the whole closet. I don’t know how dry air flows around in an enclosed space, and wondered whether it would ever displace the humid air in other parts of the case, especially inside the instrument.

 

> Does it come with a humidity gauge?

 

I added one, which fits in the main part of the case next to the heel. It shows humidity as a fairly constant 50-55%, which I think is fine. But I should look for a gauge that measures the inside of the box.

 

> The real danger to your guitar is low humidity. The top wood in particular changes dimension a lot with humidity changes, and cracks ensue when the humidity gets much lower than the humidity at which the guitar was assembled.

 

That’s my understanding as well. I don’t have low humidity here, except on infrequent days when the Santa Ana winds, hot dry air off the desert, blow through.

 

> There is a guitar case humidity control device available—I don’t have a link—that uses a salt that maintains humidity at a good level. It removes moisture when the humidity rises, and adds moisture when the humidity falls. It’s just the physical characteristic of the salt. A student of mine that runs a calibration lab uses the stuff to calibrate humidity gauges!

 

That would be a nice device to have, in another climate. I’ll look for that and keep it in mind if I move. As is, dehumidification is all I need — and I need to find a gauge that fits inside the box or at the sound hole.

 

Thanks for your well-informed answer.

 

John R.

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