https://thecavepearlproject.org/2024/04/20/a-practical-method-for-calibrating-ntc-thermistors/
I have developed a two stage thermistor calibration method that is different from the ice-cube & boiling water that people often use. The first procedure puts the loggers in distilled water, inside an insulated lunch box and freezes it overnight, using the thermal plateau just after ice nucleation as the 0C calibration point. While this takes longer than the traditional ice-slurry it can be done in a batch process.
The second warm calibration point is gathered with a hard-sided lunch box warmed by an 8 watt reptile heater pad. These sell for about $15 on Amazon and because they don’t cycle, they give you the kind of nice smooth curve needed for calibration. The third temp/resistance pair is gathered in the same kind of insulated lunch box that is simply left at ambient room temp.
Aside from the Si7051 reference sensor modules which we order online, the insulated lunch boxes and reptile heaters are easily obtained from local stores.