Darkroom thermometers

ags2mikon said:

I prefer mercury but, it is so toxic that even Ford discontinued it.

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I remember the days at school when the chemistry teacher allowed us to explore the weird properties of mercury by pushing it around on a table, splitting it and then pushing it together to form one big blob again and even handling it with bare hands.

Fascinating stuff and I warn anyone to try and tell me any different as I have become very mercurial in temperament

pentaxuser

Some of the worst mercury poisoning I saw was among a former generation of house painters. When latex indoor primers were first introduced, there were several years when those included mercury driers. And since latex simply washes off with water, they didn't suspect a thing. One the symptoms of mercury poisoning is just how erratic and downright mean people can become. The wild unpredictable behavior of Meriwether Lewis in his later years has been attributed to mercury as the routine cure for syphilis in frontier times.

djhopscotch said:

I am a fan of the Thermoworks products, Thermopen and Thermopop. They will give a reading a a few seconds, have nice long probs and are basically bullet proof.

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Also a fan. I have one and am thinking of getting another just to have it...

Mercury metal shouldn't be in your home.....Period!

Who has not seen W. Eugene Smith's photos of Minamata?

Anyone who is using mercury thermometers should probably have a spill-kit and a plan in case of breakage.

My Thermoworks Thermopop digital thermometer is acurate ±1.0°F (±0.5°C) between 14 to 208°F (–10 to 98°C), and gives a reading within 2-3 seconds. The Thermopop can be irritating to use because, by default, the display times out after 10 minutes to save batteries. That can be disabled so it stays on until you turn it off. You can change the reading to display either Celcius or Fahrenheit, but it is not very quick or convenient to switch back and forth.

If you ever have a problem with a Thermoworks thermometer, customer service is very good.

I also use a Samigon analog dial thermometer which costs about $20USD. It claims to be accurate ± 1 degree, but does not say if that is Celcius or Fahrenheit. I can adjust the dial to match my digital thermometer at 20*C, but that is a one-point calibration, so it may not be accurate elsewhere on the dial. The dial thermometer never shuts down, needs no batteries, and reads in both F and C without pushing any buttons!

One other difference, I have discovered the dial thermometer needs to have several inches of the stem immersed to get an accurate reading, while my digital thermometer will give a good reading with only about 1/2-inch of the stem tip submerged.

Seems a jolly enough fellow to me.

I have one of the lab grade spirit thermometers and while it does work well, it needs to be handled with care and isn't instant read.

I probably should get a digital and compare to the glass theremometer.

runswithsizzers said:

Who has not seen W. Eugene Smith's photos of Minamata?

Anyone who is using mercury thermometers should probably have a spill-kit and a plan in case of breakage.

My Thermoworks Thermopop digital thermometer is acurate ±1.0°F (±0.5°C) between 14 to 208°F (–10 to 98°C), and gives a reading within 2-3 seconds. The Thermopop can be irritating to use because, by default, the display times out after 10 minutes to save batteries. That can be disabled so it stays on until you turn it off. You can change the reading to display either Celcius or Fahrenheit, but it is not very quick or convenient to switch back and forth.

If you ever have a problem with a Thermoworks thermometer, customer service is very good.

I also use a Samigon analog dial thermometer which costs about $20USD. It claims to be accurate ± 1 degree, but does not say if that is Celcius or Fahrenheit. I can adjust the dial to match my digital thermometer at 20*C, but that is a one-point calibration, so it may not be accurate elsewhere on the dial. The dial thermometer never shuts down, needs no batteries, and reads in both F and C without pushing any buttons!

One other difference, I have discovered the dial thermometer needs to have several inches of the stem immersed to get an accurate reading, while my digital thermometer will give a good reading with only about 1/2-inch of the stem tip submerged.

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These new digital thermometers are very nice. I still use dial thermometers, most thermometers have a marking on the stem, standard is 76mm of immersion (c. 3 inches).

DREW WILEY said:

One the symptoms of mercury poisoning is just how erratic and downright mean people can become.

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Based on what I see these days are you sure that mercury poisoning isn't more widespread than we might imagine?

pentaxuser

I still have a few Mercury amalgam fillings in my teeth.
Although slowly releasing mercury fumes into my body the following link seems to think it is non too harmful.


I did read someplace that crematoriums may have to put in place extra precautions when cremating old wrinklies like myself having old fillings.
Apparently the mercury fumes from fillings going up the chimney may cumulatively affect the atmosphere and surrounding environments.

mshchem said:

Mercury metal shouldn't be in your home.....Period!

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If you have fluorescent light tubes fitted in your house, you have mercury in your home.

In the UK I think domestic tubes are allowed to be dumped in the rubbish bin, but industry has to have them disposed of professionally.

Stricter here. Fluorescent tubes have to go to formal recycle centers directly, not into street containers where they'd get smashed.

BobUK said:

If you have fluorescent light tubes fitted in your house, you have mercury in your home.

In the UK I think domestic tubes are allowed to be dumped in the rubbish bin, but industry has to have them disposed of professionally.

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I'm down to two fluorescent tubes, when those go I'm gonna be done. We have a disposal site.

I was under the impression that metallic mercury was less toxic than other mercury compounds and was not readily absorbed through the skin. Am I mistaken there?

And, what does a "mercury spill kit" consist of, anyway. I do have a Kodak Process Thermometer that I don't plan on breaking, but, just in case...

And what about breaking all those CFL bulbs when trying to remove them from sticky sockets. That's happened to me more than once. I hate the things and don't have any now, but they were all over my house when I bought it years ago.

Best,

Doremus

More domestic items possibly containing mercury.

Flame failure devices in gas cookers, boilers and fires.

I have only just thought of it.


I had a faulty oven cooker flame failure device in my junk bin for ages. My idea was to salvage the fine copper tubing. Fortunately someone threw it away before I found the time to cut the thing up.

DREW WILEY said:

Some of the worst mercury poisoning I saw was among a former generation of house painters. When latex indoor primers were first introduced, there were several years when those included mercury driers. And since latex simply washes off with water, they didn't suspect a thing. One the symptoms of mercury poisoning is just how erratic and downright mean people can become. The wild unpredictable behavior of Meriwether Lewis in his later years has been attributed to mercury as the routine cure for syphilis in frontier times.

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The medical kit of the Lewis and Clark expedition included a generous supply of powerful laxative pills nicknamed "Thunderclappers" which contained mercury. I think back then a powerful laxative was thought to be good for whatever ailed you. It's been said that the high concentration of mercury left in the soil from the encampments' latrines helped future historical investigations trace the expedition's route west.

The folk ballad "The Unfortunate Rake" is about a young man dying of syphilis. It has a line referring to "pills and salts of white mercury." "The Unfortunate Rake" begat a number of similar songs over the years ultimately leading in the 20th century to "The Streets of Laredo." Don't think Tex Ritter's version of this mentions syphilis or salts of white mercury.

Finally early in the 20th century the great German physician and microbiologist Paul Ehrlich (not to be confused with the guy at Stanford who's still waiting for the population bomb to explode) developed arsphenamine to treat syphilis. This was the first specific chemotherapeutic agent for treating a bacterial infection, a "magic bullet." I expect it had some unpleasant side effects since it contained arsenic, but nothing like the salts of white mercury or the insanity that could result from untreated syphilis.

Getting back to the original subject, at this point in my life I find my Kaiser digital thermometer is a lot easier to read than a column of mercury. I do check it against my Kodak Process thermometer.

David

Saganich said:

have 4 12" non-mercury laboratory thermometers, which are rated +/- 1C.

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Plus/minus 1℃ is plus/minus 1.8℉ ...which amounts to about 0.5 minute difference in developing film. One high but within tolerance vs one low and within tolerance, could cause 1 minute difference in time.

Hi David. Here along the Bay folks are discouraged from eating non-migratory fish due to all the mercury which has drifted down from your gold rush country over the past century and a half. But the actual mercury mines were within the south Bay watershed. Red cinnabar pigment was used by coastal Indian tribes for cosmetic and pictographic purposes. But it allegedly changes into its more dangerous form through enviro interactions in the water. Gosh knows how cinnabar affected the assistants of men like Michelangelo grinding it into red paint pigment, potentially even inhaling some of the powder.

I've sure seen more than my fair share of artists going semi-wacko from combinations of lead, cadmium, and cinnabar exposures. The effect on the liver and kidneys was even worse. There seems to be a sort of macho attitude among them about not wearing gloves or respiratory protection. Some of those bad habits passed over to a former generation of photo alt printers handling nasty substances. "Street artists" using spray paint cans are harder to diagnose - are their brain cells rotted out because they used these products, or did they choose them because they were already stupid?

wiltw said:

Plus/minus 1℃ is plus/minus 1.8℉ ...which amounts to about 0.5 minute difference in developing film. One high but within tolerance vs one low and within tolerance, could cause 1 minute difference in time.

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A longish development time helps mitigate the error. For a 10-minute development time, one minute is only 10%. Still, one should pick one thermometer as a reference, preferably a reliable one, and use that to calibrate all the others one has. Then at least any error in accuracy will be consistent. It really doesn't matter if you choose your development times for 20°C or 22°C as long as you're consistent.

Best,

Doremus