Thermometer -

[Barney]

How accurate is accurate enough for a thermometer used in developing?

I carried out a rudimentary test using a glass full of ice with water added, I ended up with a reading of 0.6 degrees. I appreciate that it wont get down to Zero as I am measuring a cold liquid at just above freezing temperature.

Is it near enough?

 

[Woodsy]

The issue with calibrating measurement devices such as these is that it is very difficult to know the temperature of the thing you are measuring well enough before the calibration commences. Just ask NPL. Measuring absolute temperature is very difficult. Measuring relative temperature is easier, but tells you less information. Let's not even get started on calibration drift over time.

Generally speaking I would suggest doing test developments and log the measured temperature of the thermometer you're using with the results achieved. Over development in relation to the results you want means the temperature is too high, and vice versa.

Alternatively, if you really want to know, buy a calibrated thermometer.

For B&W, a degree either way is not likely to yield much difference, for certain stages of slide development, issues can start to creep in around a few tenths of a degree out (from what I understand)