The - Salt Test 101

Apr 7, 2006
on the grass
i hope this isnt an accidental repost.... my computer is doing strange things.

i finally broke down and got a digital hygrometer. It is being salt tested as i type this. My dial works just fine and is being moved to my 5 vegas humi and the digital one is going in the main humidor.
I only got the digital because it has an alarm for the RH being too low or too high.

... plus it was on sale for 50% off at my local shop.
Sep 29, 2006
Morgantown, WV or Fort Lee, NJ
Any thoughts on why some of the digital hygrometers say not to salt test them? Has anyone had a problem with their digital after a salt test. I've just been trusting the digital on its own.
Jul 21, 2006
Chicago burbs
Here's a question I've been dieing to ask, but been afraid to, so here goes:

Let's say I have three different digital hygrometers; one from Radio Shack, on Don Savatore, and one generic. If I lay all three side by side, anywhere in my house lets say, and all three read the exact same RH, is it fair to say that they are accurate? My logic being: what are the chances that three hygrometers, from three separate vendors could be EXACTLY the same percentage off?

If I salt-test these, and they are all exactly equally off, would it not be more likely that the salt test is wrong? Or that I'm doing the salt test wrong?
Oct 18, 2005
Lost in translation
There is nothing wrong with the test. It is scientific fact and works as long as you are performing it correctly.

Have you tested your hygrometers?
Jul 21, 2006
Chicago burbs
I suppose I meant to infer that "I" was doing the test wrong, I have no doubts about the science behind it.

Anyway, I'm doing the test again today. I took the cap from a Gatorade bottle, Kosher salt, and distilled water. I haven't been able to get the mixture to a true "paste" form, more of a slush. Not sure if that matters, but I'll check it in 24 hours and see what happens.
Feb 1, 2015
Jackson TN USA

Two things:

First, the salt-test calibration can be done using ordinary table salt, including iodized salt. The sodium chloride is what matters, any other ingredient is in such small amount that it won't significantly affect the 75% RH result. (You can also use a Boveda 75% pack; Boveda even sells a kit that includes a small pack and a plastic bag.)

Second, with digital hygrometers you always want to make sure you have a fresh battery in the hygrometer before you start. If a previously-reliable digital hygrometer in a usually stable humidor gives an unusual reading, replace the battery and recalibrate; odds are, the problem is just a weak battery rather than an actual problem maintaining RH.

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