You will need:
- An analog hygrometer
- A bottle cap the size of a water bottle cap or bigger
- A sealable plastic container or sealable plastic bag
Complete the following steps calibrate your analog hygrometer:
- Take the cap and fill it with salt until it is just under level with the top of the cap
- Add a slight amount of water to the salt in the cap in order to just make a salt paste mixture. DO NOT over saturate.
- Place the cap with the pasty salt mixture in to the container or bag and be careful to not spill its contents
- Place the analog hygrometer into the container or bag as well
- Seal the container or sealable bag air tight
- Wait for twenty-four hours
- Take out the hygrometer from the container or plastic bag
- Check and note the reading on the analog hygrometer
- If the hygrometer does not read seventy-five degrees adjust by inserting a flat head screw driver in the back of the analog hygrometer in the center knob and turning either left or right until it reads seventy-five degrees. Turning left will dial the hygrometer up and turning right will dial it down.
If you have followed these steps you have now successfully calibrated your analog hygrometer