Mercury thermometer recommendation?

Radost · May 23, 2023

Anybody has a Mercury thermometer recommendation and where to source it?
I purchased a thermoworks one but I feel it got a little off with time.
I simple mercury thermometer with give me the most consistent and accurate reading.

titrisol · May 23, 2023

In this day and age a digital thermometer is a better investment.
Mercury thermometers drift over time, and need maintenance (and can break)

I buy type K thermocouples from Omega and have a Fluke 51 reader that is calibrated easily.

Radost · May 23, 2023

How does mercury drift overtime? What maintainable do they need?

xkaes · May 23, 2023

I've used a UNICOLOR Precision Thermometer for years -- in addition to the typical dial thermometers. It's 12 inches long and comes in a protective, plastic tube. I have no idea about their availability or price nowadays.

xkaes · May 23, 2023

Radost said:
How does mercury drift overtime?

Gravity.

Radost · May 23, 2023

xkaes said:
Gravity.

Huh???what does it do to mercury?

Radost · May 23, 2023

titrisol said:
In this day and age a digital thermometer is a better investment.
Mercury thermometers drift over time, and need maintenance (and can break)

I buy type K thermocouples from Omega and have a Fluke 51 reader that is calibrated easily.

That omega Type K has +-1.1F accuracy. Not ideal for C41

Radost · May 23, 2023

titrisol said:
In this day and age a digital thermometer is a better investment.
Mercury thermometers drift over time, and need maintenance (and can break)

I buy type K thermocouples from Omega and have a Fluke 51 reader that is calibrated easily.

Mercury thermometer is forever unless it gets cracked

Paul Howell · May 23, 2023

I have a very old Kodak color thermometer, I use to keep my analog dial thermometer in range, I find it easer to read the dial. No sure still makes mercury thermometers. Just looked at Amazon, did not see a mercury, most are listed as mercury free.

Radost · May 23, 2023

Paul Howell said:
I have a very old Kodak color thermometer, I use to keep my analog dial thermometer in range, I find it easer to read the dial. No sure still makes mercury thermometers. Just looked at Amazon, did not see a mercury, most are listed as mercury free.

Amazon don’t sale them. But lab supply stores do. I live in a state where they are not banned.
Might snatch an old Kodak from EBay.

Paul Howell · May 23, 2023

Yeah did find one, not cheap $49 or so, I could have one sent to me as I live in Arizona.

Radost · May 23, 2023

Paul Howell said:
I have a very old Kodak color thermometer, I use to keep my analog dial thermometer in range, I find it easer to read the dial. No sure still makes mercury thermometers. Just looked at Amazon, did not see a mercury, most are listed as mercury free.

Man there are ao many kodaks on ebay!!!!
Had no idea.
Will grab one.

Chan Tran · May 23, 2023

I have the Kodak Process Thermometer 3 which is very accurate within its narrow range. I also have the Fluke 51 II and it's nice but not as accurate as the mercury thermometer.

Sirius Glass · May 23, 2023

Radost said:
Mercury thermometer is forever unless it gets cracked

If the Mercury separates, shake it down and/or heat it up to get the parts together.

Radost · May 23, 2023

So plan is to keep using the Thermoworks one because of how quick it gives me a reading. But will keep the kodak mercury one inside the c41 and confidence compare to the thermoworks one reading.

Radost · May 23, 2023

Sirius Glass said:
If the Mercury separates, shake it down and/or heat it up to get the parts together.

Yea i grew up with mercury thermometers in former soviet union . . .

xkaes · May 23, 2023

$49????????? CRAZY.

Here's a great price on a UNICOLOR:

https://www.ebay.com/itm/194203738702

Radost · May 23, 2023

Just got this for $19 shipping included.

Kino · May 23, 2023

Luckily, I found 2 brand new Kodak Process Thermometers in a local thrift store. The metal ends can be kind of a pain, but they are very accurate to calibrate those cheap dial-types.

MattKing · May 23, 2023

Kino said:
Luckily, I found 2 brand new Kodak Process Thermometers in a local thrift store. The metal ends can be kind of a pain, but they are very accurate to calibrate those cheap dial-types.

My Kodak Process thermometer is carefully stored upright in a corner of a particular cupboard.
I bring it out regularly to check the continuing accuracy of my inexpensive digital and dial thermometers, which I use on an everyday basis.
The digital and dial thermometers differ in a consistent way. Using them both gives me a further double-check on their reliability - based on the assumption that if they go "off", they are unlikely to both do so in the exact same way.

Paul Howell · May 23, 2023

Radost said:
Just got this for $19 shipping included.
View attachment 339510

Looks like the one I have.

Radost · May 23, 2023

MattKing said:
My Kodak Process thermometer is carefully stored upright in a corner of a particular cupboard.
I bring it out regularly to check the continuing accuracy of my inexpensive digital and dial thermometers, which I use on an everyday basis.
The digital and dial thermometers differ in a consistent way. Using them both gives me a further double-check on their reliability - based on the assumption that if they go "off", they are unlikely to both do so in the exact same way.

I did tests back when my kid was born and i remember all the thermometers i got were not consistent. They would show different readings plus minus up to 1.5f “3f range. the best one was plus minus 1F.
For example one thermometer would show 96.6. 10 seconds later 96.2 and 10 sexond aftwr that 97.1
I dont think the calibration is what is off and it is bot consistently off.

Maris · May 23, 2023

I won't have a mercury thermometer in my darkroom. If the bulb breaks and scatters globules of mercury and the clean up is not perfect then mercury vapour will contaminate the darkroom air for years. One thermometer's worth of mercury will deliver several multiples of the safe environmental exposure limit for mercury vapour. Loose mercury hidden in gaps and cracks can be neutralised by swabbing with dilute sulfide based sepia toner which converts mercury to the non volatile sulfide. Smelly but effective.

Spirit thermometers are what I use in the darkroom but they are checked and calibrated against a precision laboratory mercury thermometer kept elsewhere; just not in the darkroom.

Radost · May 23, 2023

While i understand the concern, small amount of mercury will have no effect on me. I must had maybe 10 Russian mercury thermometers broken on my floor in my room growing up. My kid does not go in that bathroom.

Brendan Quirk · May 23, 2023

Mercury thermometers can vary in accuracy by several degrees, although precision (reproducibility) is good. I used to calibrate our lab mercury thermometers against special traceble (NIST) thermometers, so we would know what to add or subtract to get an accurate reading. Therefore, do not assume a mercury thermometer is accurate, but it probably is reproducible.

Mercury thermometer recommendation?

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