You’ve brought your new humidor home and now it’s time to prepare it for your cigars. One of the tasks you will need to complete is to calibrate your hygrometer. All hygrometers should be calibrated regardless of whether you have an analogue or digital hygrometer. Calibration is nothing more than a way of checking the accuracy of your hygrometer.
The simplest home calibration test involves nothing more than table salt, tap water, the top from a soda bottle, and a zip-top bag. Make a mixture of one part salt with one part water. The mixture shouldn’t be too dry (paste like) or too wet (salt swimming in water). The mixture should truly be a 1-to-1 ratio of salt to water. Pour this mixture into the soda bottle cap and place it in the zip-top bag. Now place your hygrometer into the zip-top bag and seal it shut. You’ll want to place the zip-top bag, with its contents, in a safe place that’s away from exterior doors, windows, and A/C and heater vents (both supply and return). You want to choose somewhere that maintains a constant temperature throughout the day. Then wait about 4 hours.
After the four hours has expired the environment inside the zip-top bag will have reached 750 RH (relative humidity). If your hygrometer’s readout doesn’t indicate 750 RH don’t worry. If your hygrometer is adjustable simply make the necessary changes to force your hygrometer’s readout to be 750. Be sure to read the instructions for your hygrometer before making any adjustments. If you cannot adjust your hygrometer jot down the difference between what your hygrometer states and 75O RH and keep this handy. Specifically if your hygrometer’s readout is 830 then you know your hygrometer’s incorrect by 80. And if your hygrometer’s readout is 620 then you know your hygrometer’s incorrect by 130.
Now that you’ve calibrated your hygrometer it’s time to begin seasoning your humidor. Actually, we like to promote calibrating your hygrometer at the same time as you begin seasoning your humidor in order to cut down on the number of days until your humidor can be used.