Any tricks to maintaining 20C in Jobo processors? : LUSENET : Large format photography : One Thread

I recently bought a used CPE-2 Jobo rotary processor and to date, only shoot B&W. The difficulty I have is trying to get the bath to 20C for B&W processing as I have to run my A/C A LOT to get 22-23C in the apartment and my "cold" tap water is 30C. And doesn't get much lower in "winter." (I'm in FL).

I have put ice in the bath, and keep a couple gallons in the fridge for bath water, but the processor brings the water up to processing temperature quickly, and then the temp just quickly goes up on its own toward room temp.

Anybody have any tricks to maintain a lower-than-room-temperature bath? I've read some references (Adams, maybe?) in which the author is adamant about developing B&W at the recommended temperatures. Besides shortened developing time, is there really any detrimental effects to processing B&W film at higher temps. (I'm using XTOL and T-MAX 100).

BTW, my processor maintains temp well if the set temp is above room temp.

-- John H. Henderson (, August 17, 2000



The ice you're putting in the bath should help, but may be melting too quickly. Try freezing a 1 L plastic bottle with water and inserting it into the processor, or use a couple of those reusable freezer packs that are used on picnics. If you still can't get your temp down to 20 C then process at a higher temp. As long as you adjust your time accordingly, there's nothing wrong with processing at a higher temp.


-- Pete Caluori (, August 17, 2000.

TMAX films are designed to be processed at up to 38 degrees C. The emulsion is really tough (a friend of mine actually processes TMX at C-41 settings with HC110 diluted 1:9 to 1:15 stock to water and he makes really nice pictures).

I process TMX and TMY in a Jobo processor all the time between 27 to 29 degrees C myself with D23. (Recently did some 120 sized TMX with XTOL and hated it - too little grain??)

To counter the short development times, use a more dilute developer - try 1:3, Kodak does list times for XTOL at 1:3 for temps up to 27 degrees C. You can extrapolate from there, something like 45 secs for one degree change might work - test. Goto the site and download the Xtol spec sheet.

-- K H Tan (, August 17, 2000.

I agree with Pete and K.H., a bit warmer developing won't hurt, especially with T-Max. Are you sure your processer's thermostat is shutting off the heater at the proper temp? The large volume of water in the Jobo should not rise enough during developing to seriously affect the development. Try turning off the temperature control, get the water to the proper temp and see if it will stay within that temperature for the length of the development, with only a degree or two of temp rise. T-Max was designed for higher temperature developing...the recommended temp is 75 degrees F for most developers. I have read where photographers use up to 100 degrees F for T-Max. I have developed a few rolls of 35mm at 90 degrees F when it couldn't be avoided. The time for development needs to be reduced 10 to 15 percent with constant agitation in the Jobo, so your time should be close to five minutes. If the heater is shutting off at the proper temperature, the water bath shouldn't rise but very little in five minutes. If it rises a couple of degrees, and it is that critical to you, try starting a degree or so colder and then the temp will average out. If the Jobo's tank is full, it should take a while for the water temp to rise even one degree at room temperature. Does the temperature stabalize at room temp or continue to rise? I used a Jobo for years at work here in sunny Alabama and never had problems with color or black and white.

-- Doug Paramore (, August 17, 2000.

If I let the processor sit as I should for an hour or so with the drum rolling, it settles right down at the set long as the set temp is above room temp.

When I tried to get 68F (20C), I put water in the bath that is 55-60F, set the thermostat to 20C, and let the drum roll. The thermostat clicks on and off. Very quickly, my thermometer passes 20C. This may be do to the fact that the water in the CPE-2 doesn't circulate well, and I may be reading a warm spot which may stabilize with time, but I panic and cut the thing off.

Anyway, if y'all (I'm from Alabama, too) say it's OK to process TMAX/XTOL at higher temps, I'll ignore Saint Ansel and I will try it a few degrees C above room temp and go 1:3 to lengthen processing time so my times are relatively more accurate.

I need 150ml of full-strength XTOL to develop 6 sheets of 4x5. I have the 2521 drum with 6-sheet reel. 1:3 gives me a total of 600ml, which is the max volume that the CPE-2 is supposed to handle, so it looks doable.

Thanks for the help.

-- John H. Henderson (, August 17, 2000.

There is _no need_ to try to maintain 68F for b&w processing, especially with modern hardened films; actually with some films (Verichrome Pan in particular) you might cause reticulation or other emulsion damage by going from such a low process temperature to a high wash temperature.

The only person I know of who has run systematic, repeatable tests of the effects of development temperature is Dr. Richard Henry, and he tested only Pan-X, Plus-X and Tri-X. The result was that he found that _for those films_ the temperature that gave the lowest granularity (there were no other significant differences) was 72F; lower and higher temperatures gave more granularity.

While the changes in granularity were measurable, _they may not have been visible_ and they can be assumed to be applicable for _only the developer and films tested_.

Ansel was correct _at the time_. Old films weren't prehardened and suffered all sorts of defects if the process temperature was too high or temperatures varied too widely; the important thing to note is that none of us, other than those using VP, are using those films and haven't for at least a decade or more. The names of some films such as TX have stayed the same but the emulsions have changed dramatically over the decades.

Here in Florida trying to get 68F water without a chiller can be a royal pain and can be extremely difficult to maintain.

I routinely process HP5+, Delta 100, TMX and Tech Pan at up to 80F without any problems or differences I can see, even with 30X magnification. The only occasional problem is ending up with a development time that's way too short for good evenness; this is usually solved by using a higher dilution.

-- John Hicks (, August 17, 2000.

John, you mentioned the water didn't circulate well. The Jobo I used had pretty good circulation. Since you said you bought the Jobo used, it could be stopped up partially. I would check the inlet to the pump and also the hoses. If you disconnect the hose to the pump you ought to be able to back-flush the inlet section. You could have a bit of paper or other blockage. That would certainly make the heater act up. You might hook up a hose to the outlet from the pump and flush it out. It's worth checking.

-- Doug Paramore (, August 17, 2000.


I live in S. Florida and always had the same problem as you. I eventually stopped worrying and started deveoping in Pyro. With pyro I could process at up to 80F and suffer no degredation in negative quality. For each degree F over 70F you just deduct 4% from the processing time.

Eventually I purchased a chiller and it is hooked to my sink and Jobo. Makes life a lot easier.

-- Mike Kravit (, August 17, 2000.

Thanks for all of the help. I began calibrating my processing times last night, and did all of the processing at 27C, which the machine happily maintains in my apartment all day long. I looked at the temperature of things sitting out - my dry Jobo thermometer, a bottle of water - and they were 25C, so I set the temp a few degrees higher so that the ambient and heater can "fight it out." Haven't printed the negs yet, but they look good. Went with XTOL 1:3 to increase development time, but I don't know how well it's going to work when I do more than 1 or two sheets at a time and need up to 600ml of diluted developer for 6 sheets. That's enough to pour out of the drum (2521) when on its side.

The CPE-2 does not have a pump. I didn't realize that the CPA-2 and CPP-2 DID until hearing that from Jobo a month or so ago. They tell you to keep a drum running on the machine to stir the water. I've heard of people putting aquarium pumps in their CPE-2. I'm probably going to run over to Petsmart and get one some day soon. That sounds better to me that "using up" my rotation motor heating up the bath.

-- John H. Henderson (, August 18, 2000.


My tap water is 28-30C, so I keep a couple gallons of tap water in the fridge. When I'm ready to process, I pour a chilled gallon in the CPE-2 and finish filling directly from the faucet. I set the temp to 27C and the temperature gets there fairly quickly, and the machine holds it fine indefinitely.

I have the 2521 tank with the 6-sheet reel. Since I need 100 ml of undiluted XTOL for each 80 in^2 of film, I'd need 150 ml for 6 sheets, and at 1:3, would require 600 ml of diluted solution. This is max capacity for the CPE-2 (based on the ability of the rotation motor to turn it), but 600 ml seems way too much for the tank - without the lid firmly on, it will pour out. 400 ml seems a more reasonable max, but I'd still feel better with more like 300ml. I can go 1:1, but that decreases my N developing time to about 6 minutes. I've settled on 10 minutes for 1:3 27C, and don't think I want to go much lower.

Can anyone suggest an easily-available, non-exotic commercial developer that can process 120 in^2 of film at 27C in 270-300 ml of solution for 10 minutes or so?

-- John H. Henderson (, August 21, 2000.

I'd say Xtol ;-) (seriously)

-- K H Tan (, August 21, 2000.

A Jobo can only cool to the temperature of your tap water, and it is a trmendous waste of water to let it try to cool then. Some suggested that the heating element might be working too much but that isn't likely. Since I don't use all the chemical bottles in my Jobo ATL-2 (a CPP-2 with brains and auto lift) I freeze water in a Jobo 1 liter bottle and insert it in an unused chemistry bottle slot. When it melts I insert another, etc. This makes the water in the water bath of the processor tend to be too cold even in very warm temperatures, and the heating element kicks in to bring it down to my set temp. Of course, TMX and TMY are great at higher temps. so this is not necessary if all you do is process these films.

-- Rob Tucher (, August 29, 2000.

> I freeze water in a Jobo 1 liter > bottle and insert it in an unused chemistry bottle slot.

That's a wonderful idea!

-- John Hicks (, August 29, 2000.

The "Processor Tips and Maintenance" section of Jobo's CPE-2+ manual details that procedure (ice in a bottle) for processing below ambient temperature.

-- Sal Santamaura (, August 29, 2000.

Convergent evolution! Never seen a CPE-2+ manual. Calling Jobo with such problems usually ends in some great ideas and help because, while they are very busy and usually have to call you back, they are helpful and knowledgeable and always ready to listen and help, from my experience.

-- Rob Tucher (, August 30, 2000.

No need to bother calling. Go to and peruse the manual for any of their products.

-- Sal Santamaura (, August 30, 2000.

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