Mercury thermometer recommendation?

[Radost]

Fischer is having a blow out sale on calibrated mercury thermometers. This one is full immersion, so it is used to test your other thermometers.
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Link??

 

[ic-racer]

Spelling corrected and link added.

 

[Kodachromeguy]

Mercury thermometers drift over time, and need maintenance

This does not make any sense. If the glass tube is sealed and intact, it is not going to drift. How do you maintain a sealed thermometer? And it will work in any gravity as long as it is sufficient to pull the column of mercury down into the bulb.

 

[Chan Tran]

This does not make any sense. If the glass tube is sealed and intact, it is not going to drift. How do you maintain a sealed thermometer? And it will work in any gravity as long as it is sufficient to pull the column of mercury down into the bulb.

I must agree with you. If for any reason the mercury is lost how can one replace it? One can't recalibrate it either as that requires drawing a new scale on the thermometer.

 

[Radost]

I must agree with you. If for any reason the mercury is lost how can one replace it? One can't recalibrate it either as that requires drawing a new scale on the thermometer.

Lost???

 

[Paul Howell]

+1 with

Lost???

From Chatbot

It is difficult to provide an exact timeframe for the lifespan of a mercury thermometer, as it can vary widely. However, with proper care and usage, a mercury thermometer can typically last for several years, and in some cases, even decades. If you notice any signs of damage, such as cracks, leakage, or inaccurate readings, it is advisable to replace the thermometer for safety and accuracy.

I bought my mercury thermometer in the 60s, matches my other Omega mercury, my dial type, today I added a digital probe thermometer, all are +1 or -1 of each other with tap water, today's AM tap water is 72 degrees + or - 1 degree. With modern color chemistry, do you need to do better than + or -1 degree?

 

[Radost]

+1 with

Lost???

From Chatbot

It is difficult to provide an exact timeframe for the lifespan of a mercury thermometer, as it can vary widely. However, with proper care and usage, a mercury thermometer can typically last for several years, and in some cases, even decades. If you notice any signs of damage, such as cracks, leakage, or inaccurate readings, it is advisable to replace the thermometer for safety and accuracy.

I bought my mercury thermometer in the 60s, matches my other Omega mercury, my dial type, today I added a digital probe thermometer, all are +1 or -1 of each other with tap water, today's AM tap water is 72 degrees + or - 1 degree. With modern color chemistry, do you need to do better than + or -1 degree?

Is this from Chat GPT???? CHat GPT is the dumbest thing in the world. This is what they call a hallucination: It is spewing imaginary made up information.

 

[Chan Tran]

Lost???

If there is a leak somehow. But if that is the case you can't fix it. If not then how it goes out of calibration. You can check the accuracy of the mercury thermometer but you can't calibrate it.

 

[BMbikerider]

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.

How can they drift over time and how do you maintain them? The mercury is in a sealed capillary tube and cannot leak, it is a finite quantity and wont evaporate. Yes small quantities can detach from the main column but usually it cab be persuaded to link up again - hardly maintenance. I have a mercury thermometer made with the Kodak brand name which now must be 30-40 years old and is as accurate now as when it was new. It came with a certification that it was accurate to .2 of a degree Farenheit. I have no reason to think it is anything lass accurate now as when it was sold to me.

 

[pentaxuser]

Is this from Chat GPT???? CHat GPT is the dumbest thing in the world. This is what they call a hallucination: It is spewing imaginary made up information.

Hasn't that been going on in the world long before there was any Chat GPT? I assume the latter at least does it by mistake rather than deliberately

pentaxuser

 

[Chan Tran]

How can they drift over time and how do you maintain them? The mercury is in a sealed capillary tube and cannot leak, it is a finite quantity and wont evaporate. Yes small quantities can detach from the main column but usually it cab be persuaded to link up again - hardly maintenance. I have a mercury thermometer made with the Kodak brand name which now must be 30-40 years old and is as accurate now as when it was new. It came with a certification that it was accurate to .2 of a degree Farenheit. I have no reason to think it is anything lass accurate now as when it was sold to me.

Yes I bought my Kodak thermometer used about 20 years ago. So it could be 40 year old. I have a relatively new Fluke 51. The Fluke is convenient to use but I would trust the Kodak mercury thermometer and not the Fluke.

 

[DREW WILEY]

I have two electronic thermometers, and neither were cheap versions, but lab quality; and they need to be routinely re-calibrated. The Kodak Process thermometer is both easier to use and more reliable. It responds faster too.

 

[faberryman]

I have a Kodak Deluxe Darkroom Thermometer. I have no idea why it is deemed "Deluxe". Maybe it is "Deluxe" because it came in a cardboard storage tube. It is supposed to be accurate to ±0.5°F from 68°F to 75°F, though I haven't made the trip to the National Bureau of Standards to have it certified. It seems to work pretty well. Some people call their darkrooms "labs". I don't, but if you do, you can say this thermometer is lab quality. Or maybe deluxe lab quality.

 

[Radost]

First one came like that. I wonder if freezer would make it join back

 

[Sirius Glass]

First one came like that. I wonder if freezer would make it join back

View attachment 340210

Hold the top end and shake it down with flicks of the wrist. One shake and check to see if there is movement. Repeat until it will not improve. Then heat gently and see if it links up but not real hot. The later try cooling down and see if that helps.

 

[Agulliver]

If mercury thermometers weren't so good, then laboratories and hospitals wouldn't have used them for decades. And wouldn't use them today. And as explained earlier, in some circumstances they are still available and preferred.

However, for colour film processing....a modern non-toxic spirit thermometer is perfectly adequate. Just be prepared to replace it more often than a mercury one. It's not like they are expensive, a good one can be had for less than a roll of Tri-X.

Mercury or anything else being "lost"? That would be a concern because it is primarily mercury vapour building up in a home that would be of concern to us. I've never heard of this. The school labs I run donated almost all our thermometers to Northwick Park Hospital at the beginning of the pandemic and I replaced nearly all with "lo-Tox" spirit thermometers. Yes, I've had more failures (broken strands) than I'd have with mercury but they're easier to dispose of...and are being handled by kids. A reasonably careful photographer ought to be able to make even a spirit thermometer last a decade. It's mostly dropping the things or heating them too high that damages them. I do keep, and bought new, some specialised mercury thermometers for things that require measurements above 300C. No photographer needs that.

So...in an ideal world, mercury if you can get it. But if not, a modern spirit thermometer is in 99% of cases just as effective.

 

[Donald Qualls]

I wonder if freezer would make it join back

There's a near-vacuum both between the main column and the detached beads, and above the column or beads -- so the only way cooling would help is if you cool the bulb and heat the top of the thermometer. Usually heating the bulb to or slightly past the top of the scale is the way to go.

 

[DREW WILEY]

Schools and homes use a lot of fluorescent light tubes which do contain mercury. Walls often have old underlying primers and latex paints from the 50's which contained mercury driers. A mercury lab thermometer would be the last thing I'd worry about. And I presume nobody's darkroom doubles as a child daycare center. Nor would I want my expensive Kodak Process Thermometer being used in somebody's mouth to see if they have a fever or not. Clinics don't use glass thermometers at all anymore. Research labs do.

 

[Sirius Glass]

Schools and homes use a lot of fluorescent light tubes which do contain mercury. Walls often have old underlying primers and latex paints from the 50's which contained mercury driers. A mercury lab thermometer would be the last thing I'd worry about. And I presume nobody's darkroom doubles as a child daycare center. Nor would I want my expensive Kodak Process Thermometer being used in somebody's mouth to see if they have a fever or not. Clinics don't use glass thermometers at all anymore. Research labs do.

There are other locations which one would be ill advised to stick a mercury lab thermometer.

 

[DREW WILEY]

My memory would have to go back about 70 yrs to recall that kind of unpleasant childhood experience. The point is, don't use the same thermometer for both! Vets take their own chances with cat claws over that kind of insult.

 

[Donald Qualls]

Vets take their own chances with cat claws over that kind of insult.

Vets usually make sure the cat is securely wrapped in a purrito before trying that...

 

[DREW WILEY]

And vets often charge more than human clinics, so often have modern equipment and measure temp electronically themselves. We had an old cat needing its teeth cleaned, and they wanted $800 to do that, anesthetizing the cat in the process. So my wife, who has surgical instrumentation skills, decided to do it herself, while I put on a thick coat and heavy leather gloves to hold the cat. The cat was well-bundled too. World War III commenced anyway; but we eventually won.

 

[mshchem]

Jobo sells a marvelous, safe, no mercury thermometer.

 

[DREW WILEY]

What's all the fuss about mercury in thermometers anyway? Do you go around dropping lenses and enlarger carrier glass too, or brown glass bottles full of chemicals? I can appreciate the point in beginner darkroom classes perhaps; but they aren't likely to need an expensive precise thermometer anyway. Metal dial-type ones are readily available.

 

[ic-racer]

I have a number of thermometers in my darkroom for comparison:

Kodak Process Thermometer type 3 (like pictured) features a metal support and protective casing for the bulb. Main advantage, other than durability, is the wide and very easy to read mercury column. Disadvantage is that mine reads in "F" so readings in my darkroom need to be converted.
I use this as my 'standard' by which other thermometers are compared. This is a beautiful item from the heyday of Kodak's involvement in film.

I'd recommend this one as they are still available on the internet and, as previously discussed, they can last many many years.