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Post by RodB on Jan 29, 2021 8:13:11 GMT
I've never bothered much before with specific reference to my guitars, mainly because some of the old Japanese ones feature laminates and seem incredibly resilient of all sorts of conditions... I do however try and keep the house well ventilated and 'dry' (i.e. avoiding 'damp' issues etc). In an old house such as ours this is of course very important! I always thought absolute humidity was a much better measure. Relative humidity changes with the temperature of course (clue is in the name) so if your house temp drops by 2 degrees the RH increases even if there is no more moisture in the air. Your house temp could climb 5 or 6 degrees but again, the same amount of water in the air will the cause the RH to drop (possibly quite significantly). Conversely, be keeping the RH constant throughout the year, unless your house stays at a dead constant temperature all year round, you are actually varying the amount of moisture in the air. So surely as a result, you also vary the amount of moisture in your guitars' timbers? Over time the wood gets to an equilibrium moisture content (EMC) that depends mainly on RH and to a much lesser extent to temperature. As you point out changes in ambient (room or case) temperature does affect RH for a given absolute moisture content, and can therefore be used to advantage. Like you I am less concerned about some of my guitars, but the more valuable, lighter built guitars respond relatively quickly to significant RH changes, and there is mote value at risk. An added advantage of RH control is stability of geometry - no winter / summer changes in action, etc, and the guitars always sound their sweetest...
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Post by cgb on Jan 29, 2021 9:55:16 GMT
Over time the wood gets to an equilibrium moisture content (EMC) that depends mainly on RH and to a much lesser extent to temperature. As you point out changes in ambient (room or case) temperature does affect RH for a given absolute moisture content, and can therefore be used to advantage. Like you I am less concerned about some of my guitars, but the more valuable, lighter built guitars respond relatively quickly to significant RH changes, and there is mote value at risk. An added advantage of RH control is stability of geometry - no winter / summer changes in action, etc, and the guitars always sound their sweetest... Indeed, but I am still not sure I follow the logic. By monitoring and keeping a constant(ish) RH you are not keeping the moisture content of the air stable throughout the year, and hence you aren't keeping the EMC of the guitar's woods stable either. As you say the wood will absorb or lose moisture over time to match a certain RH (at a given temp, the same RH level causes different EMC at different temps) Obviously monitoring RH has a good effect, otherwise people wouldn't bother, and it certainly works better than nothing! All of this is based on my assumption that, overall, we are aiming to obtain a steady EMC?
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Post by RodB on Jan 29, 2021 10:34:48 GMT
Over time the wood gets to an equilibrium moisture content (EMC) that depends mainly on RH and to a much lesser extent to temperature. As you point out changes in ambient (room or case) temperature does affect RH for a given absolute moisture content, and can therefore be used to advantage. Like you I am less concerned about some of my guitars, but the more valuable, lighter built guitars respond relatively quickly to significant RH changes, and there is mote value at risk. An added advantage of RH control is stability of geometry - no winter / summer changes in action, etc, and the guitars always sound their sweetest... Indeed, but I am still not sure I follow the logic. By monitoring and keeping a constant(ish) RH you are not keeping the moisture content of the air stable throughout the year, and hence you aren't keeping the EMC of the guitar's woods stable either. As you say the wood will absorb or lose moisture over time to match a certain RH (at a given temp, the same RH level causes different EMC at different temps) Obviously monitoring RH has a good effect, otherwise people wouldn't bother, and it certainly works better than nothing! All of this is based on my assumption that, overall, we are aiming to obtain a steady EMC? I just follow the science - I agree it does not always seem logical In a stable RH the EMC of the wood will also be stable - except for a very small affect of temperature that in the range we experience is negligible. This might help: Example article
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Post by Onechordtrick on Jan 29, 2021 11:10:16 GMT
Thanks RodB, an interesting article.
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Post by cgb on Jan 29, 2021 12:27:59 GMT
I just follow the science - I agree it does not always seem logical In a stable RH the EMC of the wood will also be stable - except for a very small affect of temperature that in the range we experience is negligible. This might help: Example article I too follow (and understand) the science, which is why I was confused with the reasoning behind trying to maintain a constant RH. Your comment about the temperature difference having a negligible effect in the range we are talking (and I assume as such is ignored) sort of answers my query though. I was just pointing out that the actual amount of moisture in the air increases with temp for a given RH, so keeping RH constant doesn't keep actual moisture levels constant for all temperatures. You say the difference at the temp range we are talking is negligible, which is fine, and as I say answers my question. Apologies if this came across as argumentative, it wasn't meant to be! I was trying to understand why people are measuring, what seemed to me, like a strange thing to measure. Sorry if I've made this all boring... back to guitars!
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Post by RodB on Jan 29, 2021 12:59:57 GMT
Hello cgb, FWIW I saw this as a discussion based on the valid points you made - no argument intended here either. My problem is I find these things far from boring!
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Post by jonnymosco on Jan 31, 2021 15:51:44 GMT
Does anybody use a humidifier? If so, what?
Thanks.
Jonny
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Post by Onechordtrick on Jan 31, 2021 16:30:30 GMT
Does anybody use a humidifier? If so, what? Thanks. Jonny When it was very dry last week I put a wet towel on the radiator. Not very scientific but it pushed the humidity up nicely.
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Post by jonnymosco on Jan 31, 2021 18:19:57 GMT
Does anybody use a humidifier? If so, what? Thanks. Jonny When it was very dry last week I put a wet towel on the radiator. Not very scientific but it pushed the humidity up nicely. That's exactly what I'm doing at the moment. Thankfully it is only upstairs I have a problem and I keep my guitars downstairs usually. Jonny
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Martin
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Post by Martin on Jan 31, 2021 21:29:03 GMT
I’m using one just now, puts water vapour in the air and keeps rh at abut 45%
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Post by robmc on Feb 1, 2021 17:53:31 GMT
I’m using one just now, puts water vapour in the air and keeps rh at abut 45% sounds like my dog
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Post by Gregg Hermetech on Feb 7, 2021 18:08:45 GMT
I keep my guitar out on a stand when the RH in the room is between 42.5% and 60%. When it falls below that (it got down to 18-22% for a few days a couple of weeks ago!!!) it goes back in its case with a pair of D'Addario humidifier packs, one in the sound hole and one under the neck/headstock. If I want to play it it goes straight back in the case when I have finished. It has yet to go above 60% but it could easily happen in a Milanese summer, if so, back in the case... It's kinda good as it encourages me to play my electric more too. I've been measuring RH for a couple of years, just for fun, but it only became a concern when I got my Lowden last year. My Faith has been out on a stand for nearly five years and is showing no problem signs, but I know it could happen at any time, and also that cheaper guitars can be braced stronger, so again less of a concern.
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Post by Onechordtrick on Feb 13, 2021 14:14:14 GMT
Was 29% here today Towels have been deployed
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Post by Gregg Hermetech on Feb 13, 2021 15:34:12 GMT
Been down to 19% in last 24 hours here.
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Post by Onechordtrick on Feb 13, 2021 16:19:02 GMT
Been down to 19% in last 24 hours here. Ouch! That’s dry!
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