Hi all, been reading for a long while, but decided to sign up to share something I found tonight that may be helpful.
To calibrate your hygrometer you will need table salt,
a see through container such as a Ziplock baggie,
and a small shallow open container, like a bottle cap.
Place a teaspoon or so of salt in the shallow container
and add a few drops of water to get it wet.
You don't want to dissolve it, just get a good damp pile of salt
in your container. Remember, you don't want a salt water solution,
just damp salt. Place the shallow container in the baggie
along with the hygrometer.
Seal the baggie with some air trapped inside
(so it is not tight against the hygrometer) and let it sit.
Allow this to stabilize for at least 6 hours (don't rush it).
After it has stabilized, check the hygrometer reading without
opening up the baggie. It should be exactly 75%.
If your hygrometer doesn't read 75% after calibration
then you have 2 choices. First you can remember the deviation
of y our hygrometer. If it read 80% then you are 5% off and have
to subtract 5% from whatever it reads. The second option is to adjust
the hygrometer if your model allows for this. Some hygrometers
have a dial on the back or side that can be turned to adjust the
unit to 75%. If yours doesn't have this, then go with option 1.
a see through container such as a Ziplock baggie,
and a small shallow open container, like a bottle cap.
Place a teaspoon or so of salt in the shallow container
and add a few drops of water to get it wet.
You don't want to dissolve it, just get a good damp pile of salt
in your container. Remember, you don't want a salt water solution,
just damp salt. Place the shallow container in the baggie
along with the hygrometer.
Seal the baggie with some air trapped inside
(so it is not tight against the hygrometer) and let it sit.
Allow this to stabilize for at least 6 hours (don't rush it).
After it has stabilized, check the hygrometer reading without
opening up the baggie. It should be exactly 75%.
If your hygrometer doesn't read 75% after calibration
then you have 2 choices. First you can remember the deviation
of y our hygrometer. If it read 80% then you are 5% off and have
to subtract 5% from whatever it reads. The second option is to adjust
the hygrometer if your model allows for this. Some hygrometers
have a dial on the back or side that can be turned to adjust the
unit to 75%. If yours doesn't have this, then go with option 1.
