Hygrometer calibration

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So, I picked up this new (old) hygro.  And looking at the "%rh" designation I start to look up the differences between RH and just plain old humidity.  I want to calibrate this unit properly and find myself second guessing calibration technique I've used in the past because "did I calibrate to humidity or %rh...?  :mellow:

The cheap-ass hygros that come with most humidors and the electronic versions all measure %rh, correct?  Or do I do other than a salt test to get this one dialed in?  I guess I could run it over to Washington Calibration.  They have been calibrating my micrometers, torque wrenches etc for years.  Could probably manage this too....


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Hey BuzzArd, I think all humidor hygrometers just measure RH. I wouldn't do a salt test as this can be inconsistent with regards to the humidity produced by the amount of salt you pour out. I would use a charged Boveda pack. I used this method to calibrate my Elie Bleu Hygrometer and it worked quite well. 

I guess if you do have the opportunity to get it calibrated by a business that specialises in instruments such as these then that would be something I would do too (if I could).

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Buy the large 75% Boveda pack and a large 65% Boveda pack....not the Boveda "calibration kit"...

Try the 75% first in a sealed Tupperware (just slightly larger than needed to fit in) for a minimum of 24 hours.  Then try the 65%.  Put in an electronic hygro you trust along with this mechanical one just to compare.

You'll know after that.  Looks like a precision German instrument.

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Yea I agree. Do not buy the Boveda "Calibration kit" I made the mistake once of carelessly throwing it into my cart when shopping online. All it had was a Boveda pack and a zip lock bag!!! Grrr!!

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On 1/20/2017 at 10:43 AM, PigFish said:

If it is important to you, I would buy the 3 point cert. Make one point the point you wish to store at, and at the temperature you wish to store at and make it known to the certification company.

Cheer! -Piggy

Wondered if (hoped) you'd interject, Piggy.  Don't have your email and know you don't check PMs frequently.  Was thinking same.  Washington Calibration is fantastic with everything they work on for me and I'll plan to stop by there this week.  Problem with the vintage ice box is it will not be cooled.  Living room temps range 67-83 degrees depending on time of year.  Not sure how well they can dial it in given such a range.

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