Hygros with multiple personalities?

[smokintexas]

About two months ago I got a Xikar digital hygro, did the salt test, and after about 18 hours it was steadily reading at 75%. A few days ago I got two more and decided to salt test them together. It took a bit longer, about 24 hours, but they seemed to be holding steady at 75% as well. I threw one of the new hygros in the humi with the old hygro to compare them and they were completely different. The new one was reading at about 63% and the old one was reading at about 72%. Seeing the disparity I decided to salt test all three again to guarantee accuracy. After 8 hours in a double ziplock bag with a shot glass of salt/distilled water (mushy with no extra water floating on top) all three hygros are reading at drastically different RH. One of the new ones is reading at 66%, the other new one is reading at 74%, and the old one is reading at 85%. My question is this: Does this happen a lot? I know I can just adjust them, but I am worried about false readings going forward. The two brand new ones were salt tested together and reading the same thing yesterday, but one day later and they are reading 8% different, what could be going on here guys?

Edit to say that it's table salt that I'm using.

 

[northernmoris]

What are you using for a humidifier? If its HF beads, I would just maintain them and not worry. I know, if you told me that I'd say your crazy..

 

[smokintexas]

What are you using for a humidifier? If its HF beads, I would just maintain them and not worry. I know, if you told me that I'd say your crazy..

In my desktop I have a drymistat tube, but in the Vino I'll be using the HF beads and while I do trust the beads I'd also like to have the peace of mind of having a couple of hygros in there. I'll probably just adjust all three of them in a few hours and throw 'em back in and assume everything is kosher. I was just surprised to see such a large disparity in the RH readings from the three hygros.