I have been using the salt test for about 5 years, and I get good results. With the introduction of the Boveda pack from Humidipak, there will be no more salt tests for me. I have been using the 69% Boveda pack for my personal humidors and for business purposes. Just amazing results. Humidipak claims accuracy within a half a %, and they are not lying. I have checked and rechecked and tested and retested using expensive hygrometers that have been tested in certified labs. The Boveda pack is accurate. whether you have a $10 hygrometer, or a $300 hygrometer, the Boveda is what you should use to calibrate your hygrometers.