The Salt Method

• 1). Remove the hygrometer from the humidor and place it in the plastic bag or clear plastic container.
  
  
• 2). Fill the bottle cap or other small open container with table salt. Moisten the salt with water. Just a few drops are necessary; do not use so much water that you dissolve the salt. Carefully place the container with salt into the plastic bag with the hygrometer and seal the bag.
  
  
• 3). Wait at least six hours, then read the hygrometer through the plastic bag without opening it. If the reading is 75 percent humidity, your hygrometer is accurate and needs no calibration.
  
  
• 4). Adjust the hygrometer if the reading is not 75 percent. Adjustable hygrometers usually have a screw or dial on the back. Try to adjust this through the side of the plastic bag without opening it. If this is impossible, open the bag and quickly adjust the hygrometer before the reading can change. Set the dial to read exactly 75 percent. Return the hygrometer to your humidor.
  
  

The Saturation Method

• 1). Soak a washcloth or small towel in water and wring it so that it is wet, but not dripping.
  
  
• 2). Remove the hygrometer from the humidor and wrap it in the damp towel.
  
  
• 3). Wait one hour, then unwrap the hygrometer and observe the reading. It should indicate a 98 percent humidity level. If it does not, quickly adjust the hygrometer so that it reads 98 percent. Return the hygrometer to your humidor.