Hygrometer Calibration

[Russ Blair]

  Hello everyone, I just bought a couple new digital thermometers/hygrometer as back ups. Funny when I put them in my setter how different all three of them read. So I am running a calibration on them and figured I would pass my method on incase someone else was interested.
  First off I fill a bottle cap with table salt, milk jug caps work as well. Then I add just enough water to to give the salt the texture of wet sand. It's crucial not to dissolve the salt, or to have water standing on top. Then I place the cap and hygrometer in a plastic container, like glad ware etc. Ziplock bags will work as well if you leave plenty of air in it. The key is to make sure they are sealed to keep air from coming and going. Let them set for 24hrs, this gives the salt plenty of time to stabilize, your hygrometer should be reading 75% at this point. If it is reading different let's say 70%, you now know it is 5% lower than the actual reading. So if you run your setters at 45% you need to be getting a reading of 50% from the hygrometer in question. I normally like to check mine every year prior to hatching beginning, hope this interests you