So how close to 40-55% humidity should I be?

Discussions relating to the classical guitar which don't fit elsewhere.
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prawnheed
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Re: So how close to 40-55% humidity should I be?

Post by prawnheed » Tue Jan 23, 2018 9:35 pm

Rasputin wrote:
Tue Jan 23, 2018 9:27 pm
JohnB wrote:
Tue Jan 23, 2018 9:08 pm
Rasputin, I'm not quite sure what aspect you are dubious about. If it is about leaving the humidipaks in the case and closing the lid when the guitar is removed, the reasoning is that if the case is left open in a low RH environment the interior will tend to dry out slightly, presenting an extra "load" on the humidipaks when the and the guitar are returned. (The humipaks only contain a limited amount of usable water, at a guess 15-20ml each.) If you are going to close the case, it makes sense to leave the humidipaks inside it, especially as most cases are not airtight.

They work differently to the damp sponge type of humidifiers, in that they will attempt to maintain a set RH.
I'm just not clear how the moisture is transferred into the wood, and would like to understand this in the interests of cultivating my inner spod. If it depends on circulation of air (a bit like convection) then it probably doesn't work at all, it seems to me. Conversely, if it does work then it cannot depend on circulation of air, in which case we are saying that dry air will suck up moisture so readily that it will spread through the air like water in a sponge, and from the air which is in contact with the wood into the wood itself (a bit like conduction). That sounds plausible to me but is not what we observe with washing lines on still days, at least in temperate climates... but maybe that is different because outdoor RH is high in temperate climates, whereas we are only concerned with situations where RH is low.
Diffusion will do it. If you think how quickly the smell of a fart will spread through a room, then you'll get the idea of how quickly moisture will spread through air.

Rasputin
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Re: So how close to 40-55% humidity should I be?

Post by Rasputin » Tue Jan 23, 2018 9:51 pm

Ah yes, there is movement - just no net movement.

Jeffrey Armbruster

Re: So how close to 40-55% humidity should I be?

Post by Jeffrey Armbruster » Tue Jan 23, 2018 9:55 pm

When I wrap ginger root in a wet paper towel and put it in my windless refrigerator, moisture gets absorbed by the root.

When I recently put a new set of Humidipaks in a guitar that hadn't had any humidification for months, during a dry spell, and left the case closed for two days---the Humidipaks showed significant signs of drying out. That moisture went somewhere. I assume, the guitar and/or case.

soufiej
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Re: So how close to 40-55% humidity should I be?

Post by soufiej » Tue Jan 23, 2018 10:55 pm

"Well, it's very easy to tell when a Humidipak has dried out. Moreover, they keep a more or less constant humidity level inside of a guitar case--especially if you have a case that seals effectively. They also humidify a dry case."

"When I recently put a new set of Humidipaks in a guitar that hadn't had any humidification for months, during a dry spell, and left the case closed for two days---the Humidipaks showed significant signs of drying out. That moisture went somewhere. I assume, the guitar and/or case."




Logic is a wonderful thing! Put a damp sponge inside your guitar and then put your guitar inside a case and close the case lid. How much of the sponge's moisture goes just to keeping the case moist? Consider the typical materials used for a case and how much faster thin materials exchange moisture than do thicker, more dense materials.

And, do you really want your guitar sitting inside a damp case with a plush nylon lining?

Jeffrey Armbruster

Re: So how close to 40-55% humidity should I be?

Post by Jeffrey Armbruster » Tue Jan 23, 2018 11:48 pm

soulfiej, you're reaching. Neither of my cases are damp from using a humipak. I've never, ever heard this reported on the many threads on the topic that have appeared here over the years. Or in all of the reviews that I've read of that product. Perhaps someone will chime in now?

Again: I use a trusty hygrometer inside of my cases. It does not report dampness. On the contrary, it's usually far more 'damp' in my apartment when I'm playing than inside of my cases. Two way system that 'sort of' works de-humdifying the case.

Are you also dismissive of hospitals using thermometers and blood pressure devices and x rays instead of relying on pure observation with the eyes? And I may have missed it, but what exactly do you do if it happens that you observe that your guitar needs humidification?

JohnB
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Re: So how close to 40-55% humidity should I be?

Post by JohnB » Wed Jan 24, 2018 1:02 am

soufiej,

The humidipaks system works in a different way to using damp sponges (though various damp sponge systems, such as Dampit, are pretty widely used with string instruments).

The humidaks are designed to stabilise the RH at a set level. If the RH in the case is below that level the packs will humidify the case. If the RH is above that level they will absorb moisture. Of course, their effectiveness is influenced by how "leaky" the case is but they work pretty well with Hiscox cases, as can be seen by the chart I included in this post: viewtopic.php?f=1&t=109388&p=1248392#p1248392
Hermanos Conde 1968, Stephen Frith 2007 "Guijoso", Christopher Dean 2018, Ana Maria Espinosa 2014

soufiej
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Re: So how close to 40-55% humidity should I be?

Post by soufiej » Wed Jan 24, 2018 2:38 pm

"soulfiej, you're reaching."

People have said much worse about me. :lol:

Just consider what is actually happening inside a closed case with any moisture trapped inside.

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prawnheed
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Re: So how close to 40-55% humidity should I be?

Post by prawnheed » Wed Jan 24, 2018 2:55 pm

soufiej wrote:
Wed Jan 24, 2018 2:38 pm
"soulfiej, you're reaching."

People have said much worse about me. :lol:

Just consider what is actually happening inside a closed case with any moisture trapped inside.
It's reaching an equilibrium. Adding moisture will increase the moisture content of everything in the case that can absorb moisture. Plastics and metals don't, under normal circumstances, absorb moisture from the air so you can ignore them.

So it works fine.

soufiej
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Re: So how close to 40-55% humidity should I be?

Post by soufiej » Thu Jan 25, 2018 3:47 pm

"It's reaching an equilibrium. Adding moisture will increase the moisture content of everything in the case that can absorb moisture. Plastics and metals don't, under normal circumstances, absorb moisture from the air so you can ignore them."


The moisture content of everything in the case that can absorb moisture? That would include the case itself. I guess I just have no interest in a moist case.

Of course, plastics don't "absorb" moisture readily. But look at the mirror in your bathroom after you take a shower. It hasn't absorbed any moisture, but what has happened? That same thing that would happen with any nylon lining from a case if it were hanging in your bathroom.

Everyone gets to decide how best to treat their guitars. I just have a problem with the idea of putting my guitar in a case with a moist sponge or similar material and then closing the lid to restrict air flow.

No one's asked me but I keep my guitars on a multi-instrument stand and, if the interior air gets so dry I think I need to add a soundhole humidifer, I simply toss a cotton cloth over the guitars. At present, my Larrivee parlor, with a soundhole humidifer, is staying in a cotton pillow case on its stand by the sofa. I play that guitar almost every day and it takes just a few seconds to remove the covering.

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prawnheed
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Re: So how close to 40-55% humidity should I be?

Post by prawnheed » Thu Jan 25, 2018 4:08 pm

soufiej wrote:
Thu Jan 25, 2018 3:47 pm
"It's reaching an equilibrium. Adding moisture will increase the moisture content of everything in the case that can absorb moisture. Plastics and metals don't, under normal circumstances, absorb moisture from the air so you can ignore them."


The moisture content of everything in the case that can absorb moisture? That would include the case itself. I guess I just have no interest in a moist case.

Of course, plastics don't "absorb" moisture readily. But look at the mirror in your bathroom after you take a shower. It hasn't absorbed any moisture, but what has happened? That same thing that would happen with any nylon lining from a case if it were hanging in your bathroom.

Everyone gets to decide how best to treat their guitars. I just have a problem with the idea of putting my guitar in a case with a moist sponge or similar material and then closing the lid to restrict air flow.

No one's asked me but I keep my guitars on a multi-instrument stand and, if the interior air gets so dry I think I need to add a soundhole humidifer, I simply toss a cotton cloth over the guitars. At present, my Larrivee parlor, with a soundhole humidifer, is staying in a cotton pillow case on its stand by the sofa. I play that guitar almost every day and it takes just a few seconds to remove the covering.
If the case is made of wood, it will too absorb some of the moisture. It will be exactly like the guitar.

The reason the mirror gets condensation on it is because it is cooler than the air. The hot water from the shower heats the air as well as adding moisture. Because the mirror is cold it cools the air close to it and the water vapour in the air condenses into droplets. This also happens on the walls, but you don't necessarily see it because they are generally made of plaster which absorbs the water. Unless you cool the outside of your guitar case or put hot water in it, that will not happen with the guitar case.

Your method is fine, except that you need to add water to the humidifier much more frequently as it is losing humidity to the air in the room and will not reach equilibrium unless you seal the room and keep adding water until the entire room is humidified. The cotton bag will not act as a barrier to the water vapour leaving your guitar, but it will slow the process by reducing draughts blowing over the humidifier. So if it is particularly dry, your method is simply not going to be as effective as closing it in the case with the humidifier.

soufiej
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Re: So how close to 40-55% humidity should I be?

Post by soufiej » Thu Jan 25, 2018 9:10 pm

"Unless you cool the outside of your guitar case or put hot water in it, that will not happen with the guitar case."


I don't heat or cool my cases - intentionally at least. My recollection is the "equilibrium" is always dynamic and always seeking to balance itself. If I fill a bowl with water and then loosely cover it with a nylon cloth or a plastic wrap, in due time, the side of the cloth/plastic closest to the water will have attracted some moisture to it which will sit on its surface. The dampness comes from the bowl of water that is giving up its moisture to keep the immediate area at equilibrium.

Neither here nor there, I am not interested in "humidifying" my cases.


"Your method is fine, except that you need to add water to the humidifier much more frequently as it is losing humidity to the air in the room and will not reach equilibrium unless you seal the room and keep adding water until the entire room is humidified."


The first half of your statement is correct, the humidifier is giving up moisture to the surrounding air. At least it's not wasted in keeping the wood of my cases moist.

No need to "seal the room". If I have reached the point where I am using a soundhole humidifer, then the in room humidifier has been struggling to keep the room stable over a few days time. The in room unit takes care of the room and the soundhole device simply gives me a bit of a grace period. I could just as easily keep a bowl of water beneath the stand as the cloth will slow the passage into the room when the stand is covered with the cloth. It obviously won't stop evaporation but it will slow it some. The cloth only touches small portions of the tallest, broadest guitar(s) and never the same spots each time.

No matter what I do, if the environment in which the guitars sit is dry, then I'm going to have to continue to add water to something. I typically play several guitars in the course of a day so I have no problem keeping most of the soundhole humidifiers damp.

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prawnheed
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Re: So how close to 40-55% humidity should I be?

Post by prawnheed » Thu Jan 25, 2018 9:38 pm

I give up. Do it your way.

soufiej
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Re: So how close to 40-55% humidity should I be?

Post by soufiej » Fri Jan 26, 2018 3:40 pm

Oh! I wasn't aware I was suppose to change.


Why?

Rasputin
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Re: So how close to 40-55% humidity should I be?

Post by Rasputin » Fri Feb 09, 2018 10:15 pm

Follow up question - is the figure different for the neck and headstock, as compared to the body? I'm not in the habit of keeping my guitars in cases but realistically I suppose in-case humidification in the only way to get any moisture into the neck. I am thinking of getting a soundhole humidifier or more likely a dampit type humidifier and leaving it in overnight - once a week would probably be enough where I am now - but it won't do anything for the neck.

Can anyone recommend a soundhole type humidifier that doesn't leak?

Thanks

JohnB
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Re: So how close to 40-55% humidity should I be?

Post by JohnB » Fri Feb 09, 2018 11:08 pm

Rasputin, with the humidipak system you have one humidipak (in a pouch) at the headstock, in addition to the soundhole pouches.

I've never had a humidipak leak but there have been reports on the web of it happening in the past. Mind you I take care with how I handle them and replace the packs every so often.
Hermanos Conde 1968, Stephen Frith 2007 "Guijoso", Christopher Dean 2018, Ana Maria Espinosa 2014

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