Interesting thread, and your comment here Roger. On this side of the pond, the ideal would be to obtain a thermometer certified by the NBS (National Bureau of Standards) and compare all others to it - the master/slave thing. However, not sure we need that extreme in our darkrooms (the NBS thermometers, like everything else are quite pricey).
Like most things darkroom, we can cater to the analytical side and spend all of our time checking, calibarting, etc. NOTE:I am as bad about this as anyone, so I do not think it is a bad thing. On the other hand we should consider what we can do - in this case trying to match at least 2 "good" thermometers and keeping one as the master, then always match to it should work very well.
One question, those that use the digital thermometers, have you noticed any changes in readings when the battery starts to go? I would think that at some point the readings would become "off" just prior to the battery failure.
Originally Posted by Roger Hicks