thermometer

[Darshan]

Hi guys,
I am starting to develop c41 film.
Since temperature control is very important for this process, I don't think I will be able to use the thermometer that I develop b&w with.
I saw this on freestyle, would love to get some feedback if anyone has used it.
If you use a different thermometer, please recommend that too.
Thanks,
Darshan

 

[Dan]

That's a fine choice, especially since they provide a calibration tool.

More important is the ability to control and maintain a particular water temperature. What are you considering?

 

[x-ray]

The calibration tool isn't worth anything unless you have a standard to calibrate to.

Ive owned a number of Weston and similar thermometers that I've been given over the years and never seen one that held calibration. I gave up on them decades ago.

Get yourself a good scientific grade thermometer using alcohol in the column or even better a Kodak process thermometer. They're extremely accurate and never have to be calibrated. They're in a stainless steel sheath and fairly durable. I've broken one in fifty years. Anyway to keep the dial thermometer calibrated you have to have a lab grade thermometer or process thermometer to calibrate to.

 

[Darshan]

If I understand you guys correctly, the thermometer won't show me accurate temps if its not calibrated to a standard, right?

 

[x-ray]

If I understand you guys correctly, the thermometer won't show me accurate temps if its not calibrated to a standard, right?

You are correct. It might be or might not be accurate from the factory. They're subseptable to shock and over time drift. I have three right now that I need to toss in the trash.

I just looked on eBay ant there are several Kodak process thermometers from the mid $30 up. There's a best offer option on the $36 one and a few others. There are mercury thermometers and accurate to 1/2 degree F or less. If the mercury ever separates in the column all you have to do is place the mercury bulb in hot water to drive the mercury up the column until the separated mercury reaches the little expansion chamber at the top of the thermometer. Allow it to cool and the mercury comes back down the column and it's working again. In fifty years I e only had to do this once and it took five minutes to fix. Also these never need calibrated.

 

[Chriscrawfordphoto]

Dial thermometers are worthless, they're simply incapable of the accuracy needed for color work.

The Kodak Process Thermometer Type III is the best. Its a mercury thermometer though, and if you break it, its a pain to clean up the mess. They were discontinued years ago and usually sell for high prices on ebay now.

Check out the Paterson Color Thermometer. I have used one as well as the Kodak Process Thermometer and the Paterson matches its readings perfectly. They're about $35 new and do not contain mercury.

 

[mwoenv]

To develop color, I got a Paterson Colour Thermometer and I calibrate a couple of other thermometers to it. This way I can use any thermometer for work and not risk breaking the more expensive thermometer. Using a pot of water that I bring to the desired temperatures, I record the working thermometer's value when the Paterson thermometer reads the desired value.

 

[Darshan]

Thanks guys, I will look for a Kodak or Paterson thermometer.

 

[Corran]

I love my Kodak Process Thermometers. I bought two to replace the one I accidentally left hanging in my darkroom/shed when I moved. They were a bit more expensive than modern alternatives but they are really nice and seem to be dead-on accurate. They match each other perfectly. I have a Type 2 and a Type 3, one for color one for B&W.

 

[Roger Hicks]

Thanks guys, I will look for a Kodak or Paterson thermometer.

See also http://www.rogerandfrances.com/subscription/thermometers.html about using two thermometers, "master" (expensive) and "slave" (less expensive). From it:

It may seem odd to distinguish between accuracy and repeatability, but they are very different. An accurate thermometer, A, with absolute repeatability, will always show (for example) 20C as 20C. Another thermometer, B, less accurate but equally repeatable, may always show 20C as 19C. Yet a third, C, again fully repeatable, may always show 20C as 20.5C.

Cheers,

R.

 

[David Hughes]

Hi,

I've seen dozens of the old fashioned, long with blue alcohol, photographic thermometers being given away at silly prices (free or pennies) as no one seems to want them; makes like Paterson and Hama turn up most.

And any old fashioned thermometer can be calibrated. There's hundreds if not thousands of industries where accurate temperature control is important and dozens of firms/labs exist to calibrate their equipment. Even your local weights and measures dept. may do it; tyre pressure gauges and so on...

Regards, David

 

[Ronald M]

I have calibrated my Weston one time 50 years ago. I check against Kodak process one occasionally. 68 reads 67 and I use it that way. I have another brand I check for 100 deg color. Has not changed. 68 reads 69 on that one

 

[Darshan]

What's the difference between Kodak process type 2 & type 3?

 

[Dwig]

I have calibrated my Weston one time 50 years ago. I check against Kodak process one occasionally. 68 reads 67 and I use it that way. I have another brand I check for 100 deg color. Has not changed. 68 reads 69 on that one

I used a Weston and several similar dials over the years that I processed film. I never had issues with the dials, but it did check them against a good glass/alcohol reference thermometer regularly. I'm very careful with instruments and only occasionally needed to adjust one of the dials.

Glass thermometers mounted in holders (e.g. SS sleeves, ...) where the calibrations are on the holder need to be visually checked regularly to see that their reference mark, usually a small scratch, is properly located opposite the 20deg Celsius (~68deg F) mark. I've seen samples where the glass became loose and slipped.

 

[Corran]

What's the difference between Kodak process type 2 & type 3?

Type 2:
Only in Fahrenheit, 55-125 degree range in 1-degree intervals (wide, easy to read). Also has little arrows between 68 and 75 degrees showing typical b&w development temperature levels.

Type 3:
In Fahrenheit and Celsius, 55-140 degree range in 1-degree intervals (closer together and slightly harder to read).

I find the Type 2 better for b&w and the Type 3 better for color, as one would expect as they seem to be designed as such. The Type 3 is also better for mixing chemicals needing very high temps. Some of the solutions I've mixed are supposed to be at 125 degrees, which is the limit on the Type 2.