Best way to test a hygrometer’s accuracy………

[prflani]

Originally Posted by Rooster

Sjcarr, sorry - I wasn't very clear. They are off by 4% when sitting side-by-side in the same humidor.

It is still possible that they are both reading correctly - even side by side. Humidity is definitely not uniform with any humidor because of the continuous leakage and lack of mixing of the airspace within. Try placing both hygrometers in a sealed jar for 12 hours or more to make the comparison. If you need to add humidity to the jar to get into the 65-70% region within, try wiping the inside of the jar sparingly with a damp cloth before sealing everything up. In a fully sealed glass container like this the humidity inside will become uniform within a few hours. Don't depend on comparisons made any other way, you can chase your tail on this forever if you don't make the comparisons properly. I know this because I do have RH sensors that are calibrated anually and have already gone through what you are describing. The certified calibrated sensors I use are the TempTaleH from Sensitech and another type from Dickson. Both log temp and RH data and require connecting them to a PC when you want to view the data that has been recorded. Hope this helps .