Calibrate hygrometer (corrected title)

[Pickle-cham]

Ive seen 2 methods to calibrate could i use them to two step calibrate a cheap digital hygrometer/thermometers too see how out they are.
1st method seal salt in bag in jar add amount of water and wait 6 hours 75%
2nd way in distilled water or ro water should have 100%
Is there others fo

 

[nightanole]

The salt sealed with water in a bag is idiot proof and been used for hundreds of years. I would not get fancy. You dont even have to get the mix exact, you can eye ball it.

Or you can spend the $10-15 for the calibration packs, that are just premade salt in a bag just add water lol.

 

[Klyde O'Scope]

You're serious about this, aren't you? (Which is fine; I get that way sometimes too!)
Wish I had something else to suggest.

 

[Pickle-cham]

? yeah also check Thermo-stat probes, water coming in from tap, water coming out of ro unit (you never know when your membrane gonna fail), thermometers everything ha got to test them make sure they telling the truth??