Kodak Type 3 Thermometer Accuracy

[darkroommike]

Unless you are developing color film, which is very sensitive to temperature. Then errors can lead to crossover or altered contrast in the film.

I've processed E-3. E-4, E-6, C-41, and RA-4 professionally, and the processes are not as intolerant as you make them out to be. The 'chrome processes are, of course, the most temperature sensitive, but are also sensitive to excessive drift in pH, too much or too little replenishment, and improper agitation can also make a difference. None of these processes "explode" and go off the chart if you are off a degree. You will see any temperature drift in density before you'll see it in color balance. The Kodak specified color balance specs are there so that you have a target to aim at. Consistent lab processes are much more important (and a good densitometer).

Before I was in charge of making those decisions myself my lab managers would look at the Process Control Charts (Y-55) and if needed consult the appropriate "Z-book". Their usual response was to wait a half-hour and run another control strip. Later, when Tech-Net was a thing, we didn't change our process in any way just used Tech-Net rather than hit the books first.

Just wondering how many of you with a Type 3 Thermometer also have a densitometer and fresh control strips. (I don't, I'm retired. My processing today is all one shot, for fun.)

 

[RPC]

But if your thermometer is off a degree in one direction, and your are unaware of it, and you develop one degree off in the same direction, then you are two degrees off. That would could cause problems. I have found my thermometer to be very accurate, but even so if i am one degree off, I will go out of Kodak's specs a little. If I stick to a half a degree within 100F I am always within spec.

 

[darkroommike]

But if your thermometer is off a degree in one direction, and your are unaware of it, and you develop one degree off in the same direction, then you are two degrees off. That would could cause problems. I have found my thermometer to be very accurate, but even so if i am one degree off, I will go out of Kodak's specs a little. If I stick to a half a degree within 100F I am always within spec.

Unless your pH, specific gravity, or replenishment rate are all also off in the same direction. It's moot unless you are using a densitometer, a hydrometer, and a pH meter.

 

[RPC]

I have a densitometer, and a pH meter and use them. When pH is correct, temperature changes still give the same results I described.

Since there are these other variables that can cause problems beside temperature, that is all the more reason accurate temperature is important if you cannot measure the other variables. Problems resulting from any errors would be cumulative.

 

[mshchem]

I use my Kodak type 3 as the primary standard . Most thermometer stems have an immersion line at 76 mm, this is important . I buy aquarium LCD thermometers off of eBay , these things use a thermo couple . They match my Kodak process thermometer very well ,within 1/4 to 1/2 F, cost about 5 bucks delivered . I still use a Beseler made in Japan dial thermometer I would check every couple years rarely needs adjustment.

It's good to be accurate and precise . That's part of the fun of analog photography

Best Regards Mike