Testing Hygrometer with salt&H20

Hello everyone. First time posting:)

I am calibrating my hygrometer and I used 1/4 cup tap water with 1/2 cup salt stirred and placed in a ziplock next to the hygrometer over night. This morning it shows that I have 80% humidity in the bag. I had calibrated the hygrometer by wrapping it in a soaked distilled water cloth then after a few hours setting it to 95%(this was a week ago).


I am wondering what makes the salt/water mixture such an accurate way of judging the humidity? Exactly how accurate is that method, as opposed to wrapping it in a wet cloth? Thanks in advance.

Roham :smiley20:

Take a look at this thread about too much humidity in humidors. That should help you out a lot. The thread recommends this link: http://www.cmhc-schl.gc.ca/en/burema...cahy/index.cfm which goes into nice details about the calibration process.

Thank you, but I already read those links :smiley14:

I was wondering what makes it an accurate method.... How is it that exactly 75% humidity is achieved with a salt water mix?

I found this site which goes into NaCl (sodium chloride or simply, salt): http://www.tis-gdv.de/tis_e/ware/gewuerze/salz/salz.htm

Apparently at 75% relative humidity, NaCl crystals begin to disolve. Thus, by adding water to NaCl to its saturation point, you are basically replicating this in a controlled environment allowing you to properly calibrate your hygrometer.

I found an answer to my own question too:) Thanks Hex.

Here is another link if anyone is interested...

It's a cigar FAQ, it even has a vesion you can download to your palm.


http://www.cigargroup.com/faq/


6.1 Checking your Hygrometer Calibration
This is where the info on salt letting off 75% humidity is.

thanks for that link....just downloaded that to my palm.

lab :smiley20:

Quote:

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Originally Posted by Roham

Hello everyone. First time posting:)

I am calibrating my hygrometer and I used 1/4 cup tap water with 1/2 cup salt stirred and placed in a ziplock next to the hygrometer over night. This morning it shows that I have 80% humidity in the bag. I had calibrated the hygrometer by wrapping it in a soaked distilled water cloth then after a few hours setting it to 95%(this was a week ago).


I am wondering what makes the salt/water mixture such an accurate way of judging the humidity? Exactly how accurate is that method, as opposed to wrapping it in a wet cloth? Thanks in advance.

Roham :smiley20:

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According to other website information on the salt test, you're using to much water.

1 tsp. of salt in a milk cap size container along with a few drops of water. You do not want a salt water solution...only moist. That goes into a zip lock bag along with the hygrometer. Make sure that the hygrometer does not come into contact with the salt/cap. To make sure EXCESS air coming into the bag, it is reccomended to put the bag into another (perhaps larger) zip lock bag. Wait about 6 hrs and observer the hygrometer reading. The reading should be EXACTLY 75%. From that point you can follow the instructions for your hygrometer on how to calibrate the reading up/down to read 75%.