Calibrate Your Analog Hygrometer
- Place a teaspoon of salt in a bottle cap or small cup and dampen it with a few drops of water (without dissolving it).
- Carefully place the wet salt and the hygrometer inside a see-through container and close tightly. You can use a zip lock bag provided it seals well and you leave some air inside as well.
- Let it sit for at least 6 hours and note the reading on the hygrometer without opening the container. The hygrometer should should read 75%. The difference is how much your hygrometer is off. For example, if your hygrometer reads 70% during the salt method test this means that to obtain the real humidity level you should add 5 points.
- If you have an analog hygrometer, you can correct the reading. You will need to adjust the needle to the 75% mark by turning the screw on the back using a small screwdriver. You'll need to first carefully peel off the sticky magnet on the back of the hygrometer, and make sure to turn the screw way past where the needle is supposed to be, because it will snap back.
- Your hygrometer is now ready to be placed inside your humidor.