A: Can you test it with the salt method?
- To test your hygrometer using salt, you just need a few household supplies:
A small food storage bag that zips
A tiny cup or bottle cap from a 20-ounce soda
Some table salt
Put salt on the lid and add an appropriate amount of water to make a thick slurry. You don’t need to add too much water, just let the salt become wet. In case you accidentally add too much, you can use a paper towel to absorb the excess water.
Put the cap and the hygrometer inside the baggie. Zip it up and place it somewhere out of the way, so it won’t be disturbed during the test.
Wait 6 hours. The hygrometer will measure the humidity inside the bag during this time.
Read the hygrometer. If it shows a humidity of exactly 75%, then it’s accurate.
Click here for more details about salt method: How to Test a Hygrometer: 6 Steps (with Pictures) - wikiHow
Note: Please place the hygrometer vertically in the bag to avoid blocking sensor detecting port and causing inaccuracies.