Sorry for the delay, I just now saw this message now. Assuming your humidor is of the desktop persuasion, it's best to stick it to the underside of the lid. I always try to put the hygrometer somewhere in the middle of the humidor. Hope this helps...
Thanks, Dave! I woke up this morning and was a little disappointed to see that it's only reading 46%. I put my hygrometer in the bag about 10 hrs. ago and at that time it was reading 39%. What does this tell me? Do I need a new hygrometer?
Salt Test Calibration Instructions:
The rectangular digital hygrometer can be calibrated using the salt test calibration. To calibrate fill a plastic soda cap with plain table salt. Add just enough water to make the salt wet, but not so much that water stands on top of the salt. Place a zip lock bag flat on a flat surface. Place the salt filled cap inside the bag with the hygrometer. Seal the bag and wait 4 hours. After 4 hours have passed, push and hold the calibrate button until the hygrometer resets itself to 75%. Once the hygrometer has reset, remove it from the zip lock bag. The hygrometer is now calibrated!