The way that we measure humidity (or to be totally correc, measure relative humidity) is with a
tool called a hygrometer. You can purchase one of these at your local hardware store; they usually come with the
better thermometers. It's a good idea to take measurements in your house from different locations. The reason being
is that the relative humidity will be higher near a window that's cold, then a central wall which is warm. In a
damp basement, where moisture evaporates into the air, you will find a higher relative humidity, even if the
temperature is the same as elsewhere in the house. This will help you determine the size
of dehumidifier you should purchase for your basement, crawlspace, or your entire home.
How to Easily Calibrate Your Hygrometer
You will need:
* 1/2 cup table salt
* 1/4 cup tap water
* a coffee cup
* About a 1 gal. Ziploc bag
- Place the tap water and the table salt in the coffee cup and stir for a several seconds.
- Put the coffee cup and your hygrometer inside the plastic bag or pressure cooker, and seal tightly.
Put the bag in a draft-free place and out of direct sunlight.
- After 8 to 12 hours, note your hygrometer’s RH reading. Your hygrometer should read about 75 per cent. If
it does, you do not need to adjust it. If it does not read close to 75 per cent, note the difference between
your hygrometer reading and 75 per cent.
- If your hygrometer is adjustable, adjust the reading to 75 per cent. If your hygrometer cannot be adjusted,
record the difference you noted. In the future, each time you take a reading from your hygrometer, you will
need to add or subtract that difference.
This is real easy to do at home and will guarantee that your hygrometer is reading accurately!