Humidipak Calibration question

[Nabinger16]

I was checking a "Rectangular Adjustable Hygrometer" from Heartfelt with a Boveda Calibration Kit. This is a hygro I've had for some time, and I have successfully calibrated it in the past. I noticed after 24 hours it read 80%, and thought to myself "bingo, there's my problem." I didn't have time to take care of it at that moment, so I left it sit for another 10 hours or so. When I go to finish the job I now notice its now reading 75%. The temperature didn't change throughout the process, and the bag remained completely sealed.

Is this normal?

This is the second "Rectangular Adjustable Hygrometer" from Heartfelt I've calibrated/checked with this Boveda Calibration Kit. The kit is no where close to being out of date. Both of the hygro's "spiked" the same way, but I've never seen this before using the calibration kits in the past.

Has anyone else seen this when using these kits? At what point should I consider the RH reading accurate and adjust the hygro accordingly?

Thanks for the help,
Trent

[RonC]

give it 2 - 48 hour tests to be sure.

[SUOrangeGuy]

I have three digital hygometers and two spiked to 80 and one didn't when I used a calibration kit. They all read within one % of each other in my humi so I'd say its got to do with some hygrometers not having a linear reading above the sweet spot (60-72%).