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Old 01-09-2021, 01:40 PM
Monk of Funk Monk of Funk is offline
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Default Potassium Bicarbonate

Is there a way to test if I have in fact receive Potassium bicarbonate?

Or am I doing something wrong with calibrating my hygrometers?

I am apparently getting the same level of humidity with salt and with potassium bicarbonate when I mix them with water, and leave some of the salt, or KHCO3 dry on top of the water, and put the lot in a ziploc. They both seem to be giving me the same reading, which seems very humid to me. So, I feel like maybe I'm doing something wrong? Or my KHCO3 is actually just salt or something?

How can I troubleshoot this?
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Old 01-09-2021, 01:49 PM
Simon Fay Simon Fay is offline
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Follow this tutorial:

http://fayguitars.com/Guitars/hygrometer.html

-----

It seems unlikely that a supplier would have sent you the wrong material - especially if the container is labelled. I would recommend using a container that can be tightly sealed and would avoid using a Ziploc bag. Also, the sealed environment takes a while to reach equilibrium -- so set up your container and then check it the next day.
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Old 01-09-2021, 02:22 PM
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Originally Posted by Monk of Funk View Post
Is there a way to test if I have in fact receive Potassium bicarbonate?
I'm not sure what the humidity set point is for potassium bicarbonate. Potassium carbonate is the usual choice, with a fixed point near 43%.
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Old 01-09-2021, 02:26 PM
Rockysdad Rockysdad is offline
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Is there some confusion ? Potasium Carbonate is what should be used, not potasium BIcarbonate. ( If, I'm not mistaken)
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Old 01-09-2021, 02:27 PM
Dru Edwards Dru Edwards is online now
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Quote:
Originally Posted by Simon Fay View Post
Follow this tutorial:

http://fayguitars.com/Guitars/hygrometer.html

-----

It seems unlikely that a supplier would have sent you the wrong material - especially if the container is labelled. I would recommend using a container that can be tightly sealed and would avoid using a Ziploc bag. Also, the sealed environment takes a while to reach equilibrium -- so set up your container and then check it the next day.
This is a great tutorial with helpful pics. I'm going to try this out.
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Old 01-09-2021, 02:38 PM
Monk of Funk Monk of Funk is offline
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I'm not sure what the humidity set point is for potassium bicarbonate. Potassium carbonate is the usual choice, with a fixed point near 43%.
Dammit! that's probably the mistake I made!
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Old 01-09-2021, 02:45 PM
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Dammit! that's probably the mistake I made!
Yeah, 2 measly little atoms can make a big difference
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Old 01-09-2021, 02:46 PM
Simon Fay Simon Fay is offline
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Nice catch, Kevin. I didn't notice it. Yep, you should be using K2CO3 (Potassium Carbonate).


I encourage folks to set up this test the way that I did in my tutorial. You can dampen a pile of salt but under very specific circumstances (a very dry environment) - you can get incorrect results. If you form a "saturated solution", the test is foolproof.
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Last edited by Simon Fay; 01-10-2021 at 03:22 PM.
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Old 01-09-2021, 08:55 PM
EZYPIKINS EZYPIKINS is offline
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Never tried to measure the humidity in my guitar case. Used to need to know humidity by the hour at work. Can change by the minute. I just know my guitars are drying out, when the strings start to rattle.
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Old 01-09-2021, 09:13 PM
Earl49 Earl49 is offline
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I put my hygrometers outside for an afternoon to test their accuracy. We live about three miles from an airport with an official weather station, so that gives me a good enough check. Using the salt test, all your are doing is checking the 75% point but learning nothing about anywhere else in the operating range. We don't really care about 75% RH. At least with the potassium test you are checking the humidity range of actual concern.
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Old 01-10-2021, 06:14 AM
firstrebel firstrebel is offline
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Quote:
Originally Posted by Simon Fay View Post
Nice catch, Kevin. I didn't notice it. Yep, you should be using K2CO4 (Potassium Carbonate).


I encourage folks to set up this test the way that I did in my tutorial. You can dampen a pile of salt but under very specific circumstances (a very dry environment) - you can get incorrect results. If you form a "saturated solution", the test is foolproof.
I think it should be K2CO3
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Old 01-10-2021, 03:22 PM
Simon Fay Simon Fay is offline
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Thanks -- yep, you're correct. Typo. Corrected in my post.
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Old 01-10-2021, 04:39 PM
merlin666 merlin666 is offline
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Also keep in mind that you need 99% anhydrous reagent grade potassium carbonate for this that is available from laboratory suppliers. If you use cheap stuff from Amazon it may have impurities and be already partially hydrated, so it will not be reliable.
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Old 01-10-2021, 05:33 PM
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Quote:
Originally Posted by merlin666 View Post
Also keep in mind that you need 99% anhydrous reagent grade potassium carbonate for this that is available from laboratory suppliers. If you use cheap stuff from Amazon it may have impurities and be already partially hydrated, so it will not be reliable.
FWIW, I purchased a bag of it from Amazon and the several hygrometers I calibrated all came in right at 43%.
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  #15  
Old 01-12-2021, 08:25 PM
Monk of Funk Monk of Funk is offline
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Here's a question. Why don't I just put some of this stuff in a container that won't leak, put humidity can pass through the membrane, and wet it every once in a while, and leave that in my guitar case?
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