[shilala]

One more thing...
I use a bag full of 65% Boveda packs to calibrate my hygrometers. It makes a lot more sense than the salt test (from a scientific calibration calibration range standpoint), is zero mess and super simple. I have about 6 of the big ones in a gallon bag and it's where I store all my extra hygrometers.
Another thing it'll do is "train" those cheesy, inaccurate brass analog hygrometers. Once they're in the bag for a few months I've had them go from off by ten points all the way to perfectly accurate just by retentioning the crust on the spring (or something). It's really pretty amazing, I discovered that one by complete mistake.