This is quoted from the operating instructions of the new digital hygrometers that I received today. I found the last sentence to be particularly comical.
WARNING: This is an electronic instrument. To maintain the warranty of this product and enjoy many years of error free operation, do not attempt to perform the following; DO NOT wrap this gauge in a wet towel to test the accuracy. DO NOT attempt to perform the salt test. DO NOT submerge the gauge in water! DO NOT microwave or insert in an oven. Should anyone suggest any of the above to test the accuracy of the [brand name of hygrometer], we recommend that you run from them immediately!
WARNING: This is an electronic instrument. To maintain the warranty of this product and enjoy many years of error free operation, do not attempt to perform the following; DO NOT wrap this gauge in a wet towel to test the accuracy. DO NOT attempt to perform the salt test. DO NOT submerge the gauge in water! DO NOT microwave or insert in an oven. Should anyone suggest any of the above to test the accuracy of the [brand name of hygrometer], we recommend that you run from them immediately!