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Calibrating Your Hygrometer

 

Tips on Dialing in Your Hygrometer

To calibrate the hygrometer that comes with your humidor its best to follow any instructions that came with the device.  If specific instructions were not included, start off by examining the hygrometer to determine if it can be easily removed or seperated from the humidor.  Some external hygrometers can be pushed out of the humidor by applying light outward pressure to it from the inside of the box.  Although most hygrometers including external types are typically removable, there some types that are not.  If you determine that the hygrometer cannot be removed, is not adjustable or is already "fixed" and "pre-calibrated" then this procedure will not be possible. If you are not certain as to what type of hygrometer you have, please check with the store you made your purchase through.  If you purchased a humidor through us, we will be able to determine the hygrometer type through the humidor item number.

Hygrometer Calibration Paper Towel Test:

This simple test will let you know if your hygrometer is reading within an acceptable range.  To perform this test, dampen a few paper towels and wrap the hygrometer in them for approximately 30 to 45 minutes (be sure they are not soaking wet). Once the time has elapsed, unwrap the hygrometer and immediately examine humidity level. If the calibration is perfect (few are), the hygrometer will be reading 100% relative humidity (RH).  However if you see a value of 90%, we can assume that the humidity reading on the hygrometer is 10% off.  When the hygrometer is in place inside the humidor and the reading is showing 65, you will know the humidor is actually sitting at 75%. If your hygrometer is adjustable, turn it over and adjust the calibration screw on its backside accordingly to show 75%. Its as simple as that.


Hygrometer Calibration Salt Test:

If you are looking for alternate option, this calibration procedure is a bit more technical. For you chemistry buffs, when water (H2O) and salt (NaCl) are in a saturated solution at equilibrium, the result is 75% relative humidity. This provides for an excellent point of reference to calibrate a hygrometer.

To get started, fill a bottle cap (from a water or soda bottle) with regular table salt. Next, place a few drops of water on to the salt to create a dampened mixture.  Make sure you do not add too much water where the salt dissolves or turns into a liquid solution.  Next, place the cap and your hygrometer inside a zip lock bag or a plastic container and seal it.  Wait 5-6 hours and check the value on your hygrometer.  If the reading is 75%, your hygrometer is accurate and calibration is not necessary.  If the reading is not 75% and your hygrometer is adjustable, adjust the calibration screw on its backside to 75%. Room conditions will quickly influence the hygrometer humidity reading so the adjustment must be done immediately upon removing the hygrometer from the bag or container.

For those who do not have an adjustable hygrometer, you will need to remember to add or subtract the difference between the test reading and 75% to determine the actual humidity level within your cigar humidor. For example, if your hygrometer test reading was 85%, then subtract 10% from the value when the hygrometer is in your humidor.

Please know that digital hygrometers are pre-calibrated and set from the factory and are generally far more accurate than analog hygrometers.  If you have a good amount of expensive cigars, and keeping tight tabs on your humidity levels is important, its suggested that you pick up a digital hygrometer.