Tuning stability and soundhole humidification

Choice of classical guitar strings and technical issues connected with their use.
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joachim33
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Tuning stability and soundhole humidification

Post by joachim33 » Mon Jan 08, 2018 7:06 am

It is winter in Europe and it is freezing outside. I am using sound hole humidification. When playing I noticed the trebles going sharp. We discussed the effect of strings warming up before, but I started to wonder whether the humidifier plays a role. I have the simple planet waves humidifier, which hangs between 3rd and 4th string and 3rd string is most affected.

I didn’t notice the strings sharpening so much in late summer when I wasn’t humidifying, but then I had D’Addario EXP 46 and now I switched back to Savarez New Cristal normal tension trebles.

Any info on the impact of humidity on string pitch? Do they go up or down when drying out? When taking the instrument out of the case/removing the humidifier, how quickly would the change of humidity affect the strings?

Thanks.
Joachim

OldPotter
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Re: Tuning stability and soundhole humidification

Post by OldPotter » Mon Jan 08, 2018 9:55 am

There is a lot of research on the absorption of water by nylon. It is supposed to expand with water absorption and also water will act as a lubricant (plasticizer) between molecules allowing a string to stretch further. A thin strip of nylon under tension is used as a sensor for simple humidistats. So I'm not sure why your strings are going sharp, but perhaps your ambient temperature is lower now than in the summer? Perhaps the change in temperature now, when you play, is larger than the summer time change????
I don't know what happens to fluorocarbon.
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JohnB
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Re: Tuning stability and soundhole humidification

Post by JohnB » Mon Jan 08, 2018 12:21 pm

This question reminded me of a recent post from "guitarrista" in which he/she said:
This however is a global property of nylon in nylon strings - they go sharp as they warm up because the structure of the bonds is such that the string expands radially when it warms up - so it is pulling itself getting slightly thicker - which makes for increased tension - which makes for a sharpening of the pitch.
So perhaps the effect you are experiencing is due to the strings warming up when you start playing, rather than due to the humidifier.

The full post is: viewtopic.php?f=43&t=117274&p=1247777#p1247510
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Jeffrey Armbruster
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Re: Tuning stability and soundhole humidification

Post by Jeffrey Armbruster » Mon Jan 08, 2018 11:48 pm

I leave the heat off in my apartment when I'm at work; in the winter, I turn it on when I first get home. My strings definitely go sharp, predictably, as the room and guitar and strings warm up. Especially the 1,2,3 strings. Like, always.

Oh and I also use the same humidipaks as you.
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joachim33
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Location: Scania

Re: Tuning stability and soundhole humidification

Post by joachim33 » Thu Jan 11, 2018 12:36 am

OldPotter wrote:
Mon Jan 08, 2018 9:55 am
There is a lot of research on the absorption of water by nylon. It is supposed to expand with water absorption and also water will act as a lubricant (plasticizer) between molecules allowing a string to stretch further. A thin strip of nylon under tension is used as a sensor for simple humidistats. So I'm not sure why your strings are going sharp, but perhaps your ambient temperature is lower now than in the summer? Perhaps the change in temperature now, when you play, is larger than the summer time change????
I don't know what happens to fluorocarbon.
Thanks so much for your input.

I am not humidifying in summer. So in winter I store with a humidifier and play in a much drier environment. I assume the strings start to dry out while playing. I am not sure how all the effects you describe affect the pitch, but a loss of weight due to drying out will lead to an increased pitch.

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