Monday, November 29 1999
Most analog hygrometers are manufactured with a tolerance of +/- 4-5%
(or more) of humidity within the range of 40-80%. Although humidity
gauges are supposedly pre-set at the factory, it's not unusual to
find the calibration off once you get the unit home and placed in
your
humidor. If you want to see how accurate your
hygrometer is,
there is a simple, easy-to-do method you can use with items found
right in your kitchen. All you need is some table salt, a sealed container
(Tupperware™ type or ZipLock™ bag) and a plastic bottle
cap.
Place a teaspoon of salt in the bottle cap and add a few drops
of tap or distilled water to moisten it. Don't overdo it. You don't
want to dissolve the salt. Add only enough water to dampen the salt.
When water is added to common table salt, it will maintain an exact
75% humidity in a perfectly sealed environment.
Carefully place the salt and your hygrometer into the airtight
container. (Try not to get any moistened salt on the gauge.) Check
the unit to assure its current reading is somewhere in the 40% to
80% range.
Seal the container tightly but don't try to remove any remaining
air trapped inside. Now, wait for at least several hours until the
environment has stabilized (this could take up to 6 hrs.). Do not
open the container. Read the gauge's humidity % level. It should be
exactly 75%. If it is not, note the deviation as being the amount
your hygrometer is out of calibration. If for example, it reads 65%,
the gauge is 10% low. If it reads 80%, the gauge is 5% high.
Carefully remove the unit from the container/bag. Assuming your
hygrometer has a calibrating screw on the back (most better ones do)
take a very small flathead screwdriver and turn it slowly while watching
the dial on the front. If your gauge was low by 10%, turn the screwdriver
so the dial is set 10 percentage points higher than it was previously.
Conversely, if your gauge was high by 5%, turn the screw in the opposite
direction to set the dial 5 percentage points lower.
Your gauge should now be properly calibrated, which will help you
maintain a healthier overall environment for your cigars. If the gauge
does not appear to be moving, try blowing warm, moist air into the
back of it. One other thing you can do, which is also another way
to test the unit, is by wrapping the hygrometer in a warm, damp paper
towel for about 30 minutes or until it reads about 80-90% +/- a few
points.
