Paterson Certified Thermometer reability

Radost · Jun 20, 2021

I washed my Paterson Certified Thermometer in very Hot Water.
I stopped after 10 seconds.
Is it possible the realability is off?

Nicholas Lindan · Jun 20, 2021

Probably not. Compare it to another high quality thermometer - a fever thermometer makes a good reference.

Radost · Jun 21, 2021

Nicholas Lindan said:
Probably not. Compare it to another high quality thermometer - a fever thermometer makes a good reference.

My other termometers are digital and not to be trusted. I will get another one for reference.
The reason I am doubting the accuracy is my house is 78F and my chems show 68F which seams too low.

AgX · Jun 21, 2021

A fluid stem thermometer can only be off after dissection the fluid stem (which can be brought together again) or after the top being fractured off by expansion.

If it is a digital one, check it at 100°F with a medical thermometer, analog or digital. (However, you would use your darkroom thermometer for B&W only at lower tempratures.)

Doremus Scudder · Jun 21, 2021

Hot tap water is usually about 50°C/120°F. If your thermometer's range is less than that, you could risk breaking the thermometer by leaving it in too-hot water for a long time (the internal pressure can crack the tube or top of the glass column). However, if your thermometer is intact and the fluid column is not separated, no damage has been done and the thermometer is likely as accurate as it always was.

Do check for cracks and fluid separation. The latter problem can be remedied by heating the thermometer slowly till the fluid reaches the very top of the column and rejoins, then remove it quickly from the heat source and let it cool slowly.

If you're still in doubt, find a reliable thermometer to check against.

Doremus

wiltw · Jun 21, 2021

Doremus Scudder said:
Hot tap water is usually about 50°C/120°F.

Hot tape water depends upon the setting of the water heater thermostat, plus losses as it travels thru pipes which may not be sufficiently insulated from heat loss.

Mine just tested to 138.6F.

Doremus Scudder · Jun 21, 2021

wiltw said:
Hot tape water depends upon the setting of the water heater thermostat, plus losses as it travels thru pipes which may not be sufficiently insulated from heat loss.

Hence the "about" in my post. The 50°C/120°F number is from the EPA recommendations.

BrianShaw · Jun 21, 2021

Doremus Scudder said:
Hence the "about" in my post. The 50°C/120°F number is from the EPA recommendations.

OSHA is less conservative and recommends 140 degrees F.

Doremus Scudder · Jun 21, 2021

BrianShaw said:
OSHA is less conservative and recommends 140 degrees F.

So, if the OP's thermometer goes up to 150°F like many Paterson thermometers do, he should be in fine shape. If he has the calibrated model that only goes to 30°C/86°F then there was a risk of damage if left in the hot water too long at either temperature.

FWIW, I like my hot tap water to be hot enough to not be able to hold my hands under, but not hot enough to scald; that's probably closer to 140°F than 120°F.

Doremus

BrianShaw · Jun 21, 2021

Doremus Scudder said:
So, if the OP's thermometer goes up to 150°F like many Paterson thermometers do, he should be in fine shape. If he has the calibrated model that only goes to 30°C/86°F then there was a risk of damage if left in the hot water too long at either temperature.

FWIW, I like my hot tap water to be hot enough to not be able to hold my hands under, but not hot enough to scald; that's probably closer to 140°F than 120°F.

Doremus

If only we knew which thermometer it was!

BTW, just another tidbit of information... I seem to recall that OSHA also recommended 122 degrees at the faucet furthest from the water heater. EPA is more focused on energy conservation. I'd hate to know the temp at my furthest faucet if I set the water heater to 120. It would likely be lukewarm. I think with recirculating hot water systems setting to lower temps might be more feasible for anyone who likes a hot shower at the far end of the plumbing system. .

cmacd123 · Jun 21, 2021

new residential systems here have to now have a temperature limiter to avoid scalding. so your hot water temperature could be dependent on where you live and when your Hot water tank was last replaced.

Radost · Jun 22, 2021

I am in Las Vegas.

DREW WILEY · Jun 22, 2021

I didn't know Patterson marketed anything resembling a true certified thermometer like the Kodak Process Thermometer. Electronic ones can sometimes be squirrelly. But any "photographic thermometer" is designed for just a specific range of readings characteristic of darkroom applications. Don't expect a realistic response outside that engineered range, either direction.

bdial · Jun 22, 2021

Paterson Certified Thermometer - 9"

DREW WILEY · Jun 22, 2021

No way that utterly cheap Paterson TOY is a real certified thermometer !!! Multiply the price by ten. Look at the thermometer selection of true scientific lab suppliers and their specifications. They can't just be mass-produced. Certifying means a trained technician takes the necessary time to make a precise comparison at critical points over the entire relevant range of that individual thermometer, with an even higher quality scientific reference standard at hand, and then includes a signed certificate assuring that this has been done. Do you think those people work for free? And nothing that cheap would even justify the effort. At $23 retail, it probably cost around $5 at most to actually make. Marketing BS labeling and the real deal are entirely different things.

bdial · Jun 22, 2021

DREW WILEY said:
No way that utterly cheap Paterson TOY is a real certified thermometer !!! Multiply the price by ten. Look at the thermometer selection of true scientific lab suppliers and their specifications. They can't just be mass-produced. Certifying means a trained technician takes the necessary time to make a precise comparison at critical points over the entire relevant range of that individual thermometer, with an even higher quality scientific reference standard at hand, and then includes a signed certificate assuring that this has been done. Do you think those people work for free? And nothing that cheap would even justify the effort. At $23 retail, it probably cost around $5 at most to actually make. Marketing BS labeling and the real deal are entirely different things.

Sorry dude, I'm just the piano player and didn't write Patterson's, or B&H's product description.
I am well aware that certification costs real money. Presumably it's "certified" against some standard that allows self-certification ,or some such.

DREW WILEY · Jun 22, 2021

All I was implying is that if you choose to use something cheap like that you keep on hand a true dependable certified thermometer as well, like a Kodak Process Thermometer Type II, to test it against. It might take awhile to stumble onto one of those at a reasonable price, but they do turn up from time to time.

AgX · Jun 23, 2021

DREW WILEY said:
But any "photographic thermometer" is designed for just a specific range of readings characteristic of darkroom applications. Don't expect a realistic response outside that engineered range, either direction.

Lab Fluid Stem Thermometers have a constant error-range over a huge temperature range (from below freezin to above boiling). And the high-resolution "photographic" ones are seemingly built the same way, just with a shorter stem for practicability.

AgX · Jun 23, 2021

A more important aspect is the handling.

To stay within the stated error-range a thermometer must be handled as prescribed. For a fluid stem thermometer it is important to what extent it is immersed in a fluid to meter. Problem is such information is hard to find. Of most of my lab thermometers I do not even know the manufacturer...

In theory at least the temperature of the lab plays a role, (or rather the difference between lab and probe), but no hint on this to be found...

BrianShaw · Jun 23, 2021

Other than Paterson and Kodak marketing claims, I can’t seem to find any information confirming traceability to standards, or certification, of either the Paterson or Kodak thermometers.

nbagno · Jun 23, 2021

I compared my "normal Patterson" thermometer to my Kodak Process Thermometer, the Patterson is exactly the same as the Kodak at 100F :-D

AgX · Jun 23, 2021

I wonder what that "certified" means. It makes me think of calibrated by an calibration authority, but such typically is expensive and aside of medical thermometers I have not come such calibrated thermometer across. And as indicated above handling issues give greater error.
For our photographic means the absolute temperature is less important than deviations between scale values, and mercury stem thermometers due to their built yield high precision

DREW WILEY · Jun 24, 2021

All kinds of officially certified glass thermometers are available from scientific lab suppliers. None are cheap. You get what you pay for. For garden-variety black and white work, a cheaper thermometer might be just fine. Even classic darkroom mixing valves weren't all that precise. But I do have an expensive recycling thermo-regulator that will keep temps inside of 1/10th degree F. I rarely use it. But there are certain applications in color printing where that kind of accuracy is beneficial, and for which something like a real Kodak Process Thermometer is the correct fit. I just happen to use one for everything because I can always count on it.

The problem with mass-produced cheap thermometers is that they very well might vary among one another. If a person standardizes on a particular one for his personal film development indices, for example, and it breaks, the next might not replicate his previous parameters. The Type II Kodak has a strong protective stainless sheath for sake of many years of service life, something common to many other expensive calibrated glass thermometers. There is just no way to make something like that cheaply.

And remember, a truly calibrated thermometer is supposed to keep a high-level of BOTH REPEATABILITY AND ACCURACY over its whole target range, and not just at one temperature point. Different temps are often used for different kinds of processes - it's not always "room temp" 20C.

BrianShaw · Jun 24, 2021

DREW WILEY said:
All kinds of officially certified glass thermometers are available from scientific lab suppliers. None are cheap. You get what you pay for. For garden-variety black and white work, a cheaper thermometer might be just fine. Even classic darkroom mixing valves weren't all that precise. But I do have an expensive recycling thermo-regulator that will keep temps inside of 1/10th degree F. I rarely use it. But there are certain applications in color printing where that kind of accuracy is beneficial, and for which something like a real Kodak Process Thermometer is the correct fit. I just happen to use one for everything because I can always count on it.

Absolutely and indisputably true. But here is something potentially interesting. I'm an "engineering standards guy" and went hunting for any information that will explain what "certified" really means in the Ilford context and couldn't find anything in Ilford literature. I was expecting even a footnote reference to a standard; even an in-house calibration process would have satisfied my curiosity. Likewise in Kodak documentation... , what "process" means in the Kodak context. There is no doubt that the Kodak process thermometer is really well-constructed and accepted as a defacto standard, but even Kodak's process calibration documentation, KODAK Publication No. Z-99, doesn't reference their own thermometer but "a thermometer calibrated in 0.1°C units, such as the ASTM No. 91C or Fahrenheit equivalent". Likewise, the instructions for the Kodak Process Thermometer make no mention of certification/calibration either. Both Ilford and Kodak seem to require accepting the claim based just on the fact that the claim was made, it seems. So to me it seems like marketing hype.

In an obscure NIST study, which I red but failed to bookmark, the researchers "cherry-picked" Kodak process thermometers to get 3 that exactly matched. They saw variability... enough to make them do thermometer assessment and some judicious sampling.

But beyond the scientific or processes requiring a really high degree of accuracy/precision... there is enough slop in photographic chemistry to allow effective use of cheaper uncalibrated/uncertified thermometers.

BrianShaw · Jun 24, 2021

PS. Here's what I use to check and re-calibrate as required, my "working thermometer" for B&W processing, an old Weston dial type.

https://www.thermoworks.com/Thermapen-Mk4?quantity=1&color=16

Comes with a NIST certification certificate and test data (see the spec sheet)

Paterson Certified Thermometer reability

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