Calibrating the hygrometer in NH...?

[aceschix]

I am having touble with the calibration of my hygrometers. I have a larger one from Radio Shack that has the outside probe (which I am not using). I have the little square Springfield one from Walmart. I started over with the process when someone told me I was using too much water. I was using 1/2 cup of water and salt. The larger one came up to 74-76%. The smaller one was about 8% off.

So last night at 6:30 I clean up and started again with 1/2 cup salt and just 1/4 cup of water. This morning neither of them have gotten to 75%. Why?

I know New England is dry this time of year. It is only about 30% humidity in my house. What do i do next? My shipped eggs should be arriving this week.

 

[lemurchaser]

It sounds like the hygrometers are wrong. As long as the room is at room temperature, and the bag is 100% sealed, it should be 75% humidity in there in about 8 hours.

 

[Intheswamp]

If the consistency of the salt/water mix was correct and the bag was sealed tight then I would say that both of your hygrometers are simply reading low and you'll need to mentally add the differences to them. You could dry the bag out, wipe the hygrometers off and let them sit an hour or so in room air, make sure the salt/water mix is pasty/gooey/whatever (but not water standing over the top of the salt), and give it another test. This would let you begin averaging your results and maybe end up with a "best" difference to add or subtract from the hygrometers' reading.

Best wishes,
Ed