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I moved into a new workshop space where I am not able to control humidity, as it is a large basement. Obviously, not an ideal guitar workshop. I bought a large metal cabinet that I plan on sealing well enough so that I can keep guitar wood in it during the build process. I got the idea from Kim Walker when I was brought along to see his shop a few years back.

My question is, how would I control the humidity in this cabinet? Do they make small dehumidifiers? Or is there some product I can use to keep humidity at 35 or 40%? Any tips would be appreciated.

Best,

Jonas

I have not tried to use a small cabinet but I'm sure others have. I use a small dehumidifier for my 15' x 22' shop. Perhaps one of the smallest room dehumidifiers would work for you?

I have to wonder, would it be feasible for you to build a small room, say 8' x 8', in the basement that you can use as a humidity controlled work area?

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Steve Smith
"Music is what feelings sound like"

I have not done this but have heard from a few folks that a light bulb in the cabinet is all that is needed to lower the humidity due to the heat that is produced.

Yes a light bulb or one of those very low wattage tube heaters will lower the humidity. Alternately you can buy very small dehumidifiers specifically designed for small cupboards.
In effect you are making a very tiny woodstore/conditioning room. The smaller the space the easier it is to control the humidity (within reason).

I don't know if it is applicable here, but in laboratories in vessels sometimes they get an exact humidity by placing in a dish of chemicals that interacts with the water in the air to keep the humidity constant. You'll have to search the Internet.

I don't believe heating the air in a sealed enclosure reduces humidity. As mentioned you can extract moisture using chemicals, bags of calcium chloride work fine. I can remember back in the 1950's having those nasty looking things hanging off the floor joist in our basement.

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Ken Cierp

http://www.kennethmichaelguitars.com/

Yes it does, otherwise my Hygrometer is telling me big lies.

Please explain -- I am not getting how this analogy relates to an enclosure where there is no place for the moisture to go/escape?
Thanks

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Ken Cierp

http://www.kennethmichaelguitars.com/

We're dealing with relative humidity. It is the amount of moisture in the air relative to the amount of moisture the air is capable of absorbing. Warmer air can hold more moisture than colder air so if you warm the air (without adding any more water) the relative humidity will be lower. Hope that makes sense.

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Steve Smith
"Music is what feelings sound like"

So is relative humidity really what affects the wood, or just the amount of moisture in the air regardless of temperature?

It's the relative humidity that affects the wood most.

Yup - I am clueless -- so the actual humidity in the sealed enclosure reflects a certain actual amount of water in the enclosure, we heat the enclosure so we can get a different calculated relative humidity in the enclosure assuming lower reading -- but there is still the exact same same amount of water in the enclosure. There seems to be more to this, dew point? equilibrium? Otherwise why would we need machines to add or remove moisture from an area? This simplistic view indicates that all we have to do is crank up the heat -- no damp basements.

BTW lets not forget that as I mentioned calcium chloride does draw the moisture out of the air. There's also other crap that is package in cargo containers to do the same thing.

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Ken Cierp

http://www.kennethmichaelguitars.com/

The other "crap" is silica gel crystals.

Yeah that's it -- I can just remember that its labelled "do not eat" I never thought it looked that yummy.

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Ken Cierp

http://www.kennethmichaelguitars.com/

You can only heat it so much before you die. I suppose if a little heat is all that is needed on a given few days, then you would be OK. Also, I suppose if you are using hot hide glue, you would get a little more open time to work. Lot of luck trying keep the humidity just right with heat.

We are not talking about an oven here. Just a few degrees of heat is all that is needed.

It is the relative humidity that affects the wood expansion the most. And yes if a place is too humid all that needs to happen to lower the relative humidity is to raise the temperature. That is why things "dry out" when the heat is on in the winter. The outside humidity is often much higher than the inside humidity simply because of the temperature difference. Since warm air can hold more water vapor than cold air the % humidity will go down as the temp goes up. The larger the temperature difference the more drastic the difference in relative humidity. The question becomes how warm will the ambient air be and can you safely raise the temp in the box enough to get the relative humidity down to the level you desire.

I get around 8% -10% drop in RH, single wardrobe with a 15 W strip tube. A lot more if I have both tubes on (30 Watt). It is by no means a sealed enclosure but then again it's a UV cabinet rather than a cabinet to control humidity. In fact I have to place a baby bottle warmer in the same cabinet, gently steaming away, to elevate the humidity back to more normal levels. When I first built the cabinet I placed an instrument in the UV cabinet to tan the wood. Within 5 or 6 hours the Back on the guitar had visibly distorted (I had both lights on, no bottle warmer). I now only use one light and the steamer. Never had a problem since.
You certainly can control RH with heat. I'm not saying that a 30% drop is possible but 10% or so should certainly be within range.
I don't know about anyone else but the RH in my workshop always seems to fall a couple of points as the heating elevates the temperature during the day. The science is what it is. No need to try and disprove it. You can waste most of your life trying to do that. Plenty of internet sites that explain it, although I'll certainly admit I had a lot of difficulty trying to understand it when I first came across the concept.

Here is a humidity calculator. You can input the temperature you are at and the humidity.

http://www.dpcalc.org/

As a previous poster said I think you will be better off plasticing off a small room size space to keep your wood in and glue up and other tasks. It might be difficult not too get the humidity too low in a metal box. That just seems a lot iffier to me.

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Michael F Smith
Goat Rock Ukulele
http://goatrockukulele.com

That's easy. Control the temperature, use an air vent, use a steamer. There, that's 3 different methods of contolling the internal humidity. Pick one, use a combination of all 3 if you want!
Folk should stop trying to pick holes in the solution and just get accustomed to the idea that the cabinet is just a tiny room. Being tiny means it's easy to control the humidity.

Why not build a closet big enough to keep your works in progress and the stash with heat and dehumidification. Seems to work for me. Although my works in progress haven't grown in size, I'm finding I may have to build a bigger closet.

My $.02 would be to partition off your shop area, could even use with 2" foam panels -- for me storing and hauling out parts to work on -- would be an extreme PITA -- of course I am not dealing with your situation or financials. But if I were forced in to the cabinet situation I'd get a real dehumidifier for convenience and piece of mind, here's one that is made for your situation.

http://www.amazon.com/Eva-dry-Electric- ... humidifier

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Ken Cierp

http://www.kennethmichaelguitars.com/

Definitely partition off a small work area!

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Pat

Thank you for all the replys. I think I remember that the closet I saw Mr. Walker using had UV lights inside, as Michael mentioned. Maybe I will try one of the small dehumidifiers, and if that doesn't work well than I'll try the UV lights and and some sort of contraption to add humidity if needed.

I would love to build a small space, that was my intention, but this is a space in the basement of my apartment that my landlord is letting me use. I only do small scale building, so I figured the closet would suit my needs, though it is far from ideal....

Best,

Jonas