Paterson Color Thermometer Separation

mwoenv

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I've calibrating my digital thermometer to a Paterson Colour Thermometer for years and and get great results developing b&w and color film and prints. I was checking calibration recently and, after getting weird results, noticed that some of the blue fluid in the colour thermometer was near the very top of the thermometer, separated from the rest of the fluid. Is there a way to get this fluid down with the rest of the fluid?
 
Did you try to shake the thermometer downward in an arching motion several times?

Best Regards,
 
Boil some water. Let it cool down for a few minutes (5-10). Dip the thermometer in it. Watch CAREFULLY. It will keep rising. Keep dipping it in and out. Eventually the separated liquid will creep into the tiny bulb at the top of the column. So will the gaps. Keep dipping until the air gaps are gone. DO NOT leave it in beyond this point or it will burst.The column will however be solid as it cools and sucks the alcohol back down.

I wish I could just show you how to do it: it really is very easy. If it doesn't work the first time, try again with slightly hotter water. Shaking down, as with a mercury thermometer, almost certainly won't work: the density of mercury is about 20x that of alcohol, so you have inertia on your side with mercury but not alcohol.

Cheers,

R.
 
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