How to Calibrate a Humidor

With the proper environment, cigars can be kept in storage for years.

Humidors are critical for storing cigars in their ideal environment for enjoyment by tobacco aficionados. They vary greatly, but at a minimum, a humidor consists of a storage container, a humidifier and a hygrometer. Too much humidity can cause cigars to become moldy and deteriorate rapidly, but too little humidity can cause them to dry out and detract from their quality. The ideal storage environment is 68 to 72% relative humidity at room temperature. A hygrometer is used to monitor and record humidity levels, and it will occasionally need to be calibrated to ensure accurate readings.

Things You'll Need

• Hygrometer
• Psychrometer
• Towel

Instructions

Good Method

1. Create a saturated environment for your hygrometer. The dew point (saturation) is reached for a given temperature when relative humidity approaches 100%.

2. Wet a towel and wrap it around the hygrometer for an hour. This will create the saturation environment needed.

3. Look at the hygrometer reading. It should read close to 100%. All hygrometers have a margin of error that varies by type and quality. If the hygrometer reading at the saturation level is less than 100%, given its margin of error, then it needs to be calibrated. For example, if the hygrometer margin of error is 2.5%, and the humidifier is reading 90% when it should be 100%, then calibration is necessary. If it is reading 98%, then it is within its margin of error and does not need calibration.

4. Calibrate the hygrometer. Calibration varies by type and model. Some analog models will have a calibration screw or other type of setting. Digital models might have some sort of electronic method for calibration. Other models may have to be sent to the manufacturer for calibration.

Better Method

1. Acquire a psychrometer. They come in manual (sling) and digital varieties. Digital psychrometers are easier to use but may themselves need calibration over time. Psychrometers are instruments designed specifically to measure relative humidity. They consist of two thermometers (wet and dry bulb). Relative humidity is calculated by the difference between ambient temperature (dry bulb) and its dew point (wet bulb). The closer the dew point is to the ambient temperature, the higher the humidity.

2. Compare the readings between the psychrometer and the hygrometer in your humidor. Again, be sure to account for the margin of error for your particular model of hygrometer.

3. Calibrate your hygrometer if the difference in readings between it and the psychrometer are greater than the given margin of error. Remember that calibration methods for hygrometers vary widely by type and model. Consult your owner's manual for proper calibration method.

Tips & Warnings

• If your hygrometer does not have a method for calibration, it can still be useful. You will just have to make a notation of the percentage of error it is reading and add or subtract to get an accurate relative humidity.

References

• LittleCigarShop: Humidor Maintenance and Setup
• CigarOne: Calibrating Your Humidor
• National Park Service: Conserve-O-Gram 3/1: Using a Psychrometer to Measure Relative Humidity