If you want to maintain the condition of your cigars, it’s best to calibrate your hygrometer once a year. This is the instrument in your humidor that measures the moisture content in the air (humidity level). A humidor that is too wet will cause mold, and a humidor that is too dry will dry out your cigars. A difference of 5% will make a big difference to your cigars. The humidity level should be about 70%.
To calibrate your hygrometer, use plain table salt (NaCl). A solution of table salt and water will maintain 75% RH in a sealed environment at room temperature.
What you need…
• One tablespoon of salt
• Small bottle cap sized container
• Ziploc bag
• Place a tablespoon of salt into the small container and add a few drops of water so you have a wet pile, not dissolved salt. (If you add too much water, just add some more salt.)
• Place the wet salt solution and your hygrometer into the bag, making sure not to spill the solution on your hygrometer.
• Press most, but not all, of the air out of the bag and seal it. (make sure that the bag is well sealed)
• Leave it for a minimum of five hours at room temperature before checking the reading.
• After five hours, read the hygrometer through the bag. It should read 75%. If not, note the reading and repeat the procedure.
• Take the average of the two readings for a good calibration figure. For instance, if you have readings of 70 and 72%, your calibration figure should be- 4%. When checking your humidor using that hygrometer, always add 4% to get the accurate reading.