I calibrated both of my hydrometers yesterday. I put 1/2 cup salt in a glass and added 1/4 cup of water. I then placed the glass and both hydrometers in a gallon ziploc bag. At the end of the 8 hours, one hydrometer read 73% and the other read 67%. So I put a little sticker on the top of each one noting how many points I had to add to each one. This morning however, both hydrometers are giving me the same reading of 54%. They are both just sitting on the counter right next to each other. I'm confused now, since if I added 8 points to the one it would be 62%, and if I added 2 points to the other it would be 56% and they wouldn't be anywhere close to the same... What do you make of this? One hydrometer is an ACU-RITE, and the other is a Springfield precise temp. Both are giving me the same temp reading.
Calibration is really only accurate at the humidity you calibrated it too. Especially with digitals... We do 75% because salt is easy to get. An 80% is the danger point most don't want to go over. Other than staying under 80% you dont need accuracy anyway. You only need consistency. If 40% is to low for you this time it will be the next time too. Does not really matter if 40% is really 40%.
