Re: Accuracy of salt test calibration
 

I found this while browsing the JR website:

"Both mechanical and electronic hygrometers are available. Typically, the mechanical ones are more attractive, while the electronic ones tend to be more accurate. But this is not always the case. Sadly, many hygrometers, both mechanical and electronic, are grossly inaccurate and require either adjustment or replacement. One of the easiest methods of verifying the accuracy of your hygrometer is to perform a "Salt Calibration Test."

Without boring you with the chemistry of why, let me simply state that this test will always result in achieving the exact relative humidity level of 75%.
Salt Calibration Test

SaltMaterials required:

* Tablespoon of plain Table Salt (NaCl - like Mortons)
* Empty Wide-Mouth Jar with lid (like an old Mayo jar)
* Bottle Cap (like those on a Snapple bottle)
* Coffee Stirrer (or other thin object with which to stir)
* Distilled Water
* Your Hygrometer

Place the tablespoon of salt within the bottle cap. Slowly add distilled water to the salt while stirring with the coffee stirrer. You want to add just enough water to moisten the salt so that it becomes a thick paste. Do not add enough water to dissolve the salt!

Place the bottle cap with salt gently into your wide-mouth jar then add your hygrometer. Make certain that the sensor is exposed and not being blocked by the sides of the jar.

Seal the jar - this test will not work if there are any leaks. Then put the jar in a place out of direct sunlight and with a stable temperature.

Leave undisturbed for a minimum of 8 hours.

Check the reading on the hygrometer through the glass jar. It should read on or near 75% RH.

Due to the salt paste reacting with the confined air the ambient RH within the jar will be exactly 75% RH. Most inexpensive hygrometers are only accurate to within 3% of 75% RH, so do not be surprised if yours reads 72% or 78% RH. Whatever it reads plus or minus from the 75% benchmark is the amount of error of your hygrometer.

What you do about an error depends on the circumstances. If your hygrometer has an adjustment potentiometer then, by all means, try to tweak it to exactly 75%. You should repeat the Salt Calibration Test after making any adjustments. If your hygrometer can't be adjusted but the reading is close, then I suggest you don't worry about it; just remember that your hygrometer is X% off - either high or low.

If the reading is grossly in error and you are unable to adjust it, I suggest you replace it.

And finally, let me say that hygrometers are not really necessary. You will find, over time, that you be able to judge the relative humidity within your humidor by simply touching and smoking your cigars.
Alternative Cigar Storage Methods"

Don't know if this helps anyone out.

Re: Accuracy of salt test calibration
 

Very informative. I just bought a Xikar hygro and am calibrating it as we speak. It is reading 80. My old one, which I was concerned if accurate, is dead on 75/76. I agree that hygros aren't necessary, but are a good indicator of when RH drops too much and gives an indicator of when to raise.

Re: Accuracy of salt test calibration
 

I managed to calibrate a Lifestyle Ambient synthetic hair large size hygrometer from Germany using a German technique of wrapping it up in a damp tea towel. This was supposed to bring it to 100% humidity. I was dubious but tried it out. The adjustment levers in this hygrometer are hard to locate at first, being accessed through the side vents. Another dificulty I experienced was in adjusting it quickly enough, because the hygrometer reacted immediately and dramatically to having the tea towel moved enough away to access the adjustment levers. However, I got it where I hoped it was at 100% which took about 20 minutes rather than the 12 hours for the salt test. To check it though, I ran a salt test the next night with "wet sand" consistency salt in a small jar lid about 3cm wide filled 3/4 full with salt and only enough water to get the wet sand consistency. The next morning it was almost dead on, reading what looked to be something like 74.99% RH. I don't know if this works for others, but it seems to have worked for me. I use the hygrometer for fragile musical instruments, so this is reasonably critical for me too.

Re: Accuracy of salt test calibration
 

Do you smoke cigars?

Re: Accuracy of salt test calibration
 

"Lifestyle Ambient synthetic hair large size hygrometer"? No thank you! My hygrometers use REAL hair. Preferably obtained from strangers on public transportation. Sure, I get slapped a lot, and MAN the amount of restraining orders against me is just ridiculous. But when I smoke my cigars...well, it's all worth it then.

Re: Accuracy of salt test calibration
 

We take our cigars seriously and maybe some of our obsession is voodoo and hair samples plucked from unwitting strangers is just one example of what a true cigar smoker goes through beyond just the glares and sniffs from offended non-smokers.

Imagine a min-smokers horror if they knew you plucked their hair to precisely calibrate the humidity level of the very cigar they find offensive? Is this irony?

Re: Accuracy of salt test calibration
 

Fixed it for silkstring's benefit. Although there is NOTHING silky 'bout those strings. ;)

Yes. Yes it is. :D

Re: Accuracy of salt test calibration
 

I didn't have much faith in the salt test until I quit using baggies for the test environment and started using mason jars. The difference in test consistency was nothing short of amazing. It's easy to check your work; salt test your hygro, then wait a few days and test it again. If you don't get a reading within a point or two, something is amiss. With a mason jar, I can always get readings that are well within the accuracy I'd expect.

The hygro I depend on most is the one in the controller in my Staebell cabinet. After a decade of solid work, I was pretty sure it was off and it got sent back to the controller vendor for a rebuild. Now it's back in business, ready for another decade. What convinced me it was really off...?? Not the hygros I have in the cabinet, though they were off quite a bit....rather, the feel and sound and way my cigars smoked, believe it or not......:2