Temperature change in development tank

tkamiya · Oct 31, 2009

I have been having issue with establishing correct development time. Obviously, one of the factors (other than the time itself and agitation) is the temperature.

I was curious about what would happen to the developer's temperature once the liquid is poured into the tank, so I did a simple experiment. For this experiment, I used no film and used water instead of my usual XTOL 1:1 solution.

Room temp is 81F
Liquid (water) temp is 70F
Tank and reel (stainless steel) is stabilized at room temp

Pour the liquid and agitate 5 times 30 second and agitate 2 times
At this time, the liquid temp is 72F

Repeat 30 minutes and agitate 2 times for the remainder

At 7 minutes mark, the temp is now 73F

According to the Kodak's chart, every degree (F) change results in 15 seconds of development time. Since the temp increased almost immediately, at the end of 7 minutes mark, the film is about 40 seconds over-developed, should I have used 70F development time from the chart.

Also, according to Kodak, 10% increase in development time will result in 10% more contrast. Therefore, I would have 7 minutes = 420 seconds, 40/420 = 9.5% increase in contrast.

I would think, due to chemical reactions, should the film in place and liquid be real developer, the temp raise will be more than my experiment.

I *think* I know the reason for my too-high-contrast problem.

The purpose of this post is to share this finding with other folks living in relatively hot climate. Hope this is useful to some.

polyglot · Oct 31, 2009

Yes, this is why people often rest their developing tanks in water-baths of the correct temperature between agitations.

ic-racer · Oct 31, 2009

Or just let everything equilibrate to 'room temp.'

tkamiya · Oct 31, 2009

ic-racer said:
Or just let everything equilibrate to 'room temp.'

Can I really do this?

Room temp for me is 82F. Extrapolating numbers in Kodak's chart, I get 315 seconds. Compensating 20% for condenser enlarger, I get 252 seconds.

That's only 4 minutes and 12 seconds....

Does anyone do this at such a high temp?

MattKing · Oct 31, 2009

This is a good reason to use a short pre-wash - it helps stabilize the temperature of the tank and reel.

In addition, you can place the tank and reel in a shallow bath of tempered water for a while before you do the pre-wash.

Finally, I would consider using a warmer temperature as your standard. 81F is probably too high, but something like 72F or even 75F is certainly workable (with something like XTOL 1:1).

Matt

tkamiya · Oct 31, 2009

This is just insane... A lot of the articles and notes I read says TMAX films are sensitive to precise development process. I now see why. In my previous attempts at 75F, and NOT taking temp rise during processing into considerations, 6 minutes resulted in too bit too contrasty negative and 5:36 resulted in too thin negative. Now, I'm down to adjusting process in 15 seconds increments and trying to stablize temp in 1 degree increments...

tkamiya · Oct 31, 2009

I see that until I get a good handle on temperature stablization, any time test I do would be meaningless...

MattKing · Nov 1, 2009

tkamiya said:
This is just insane... A lot of the articles and notes I read says TMAX films are sensitive to precise development process. I now see why. In my previous attempts at 75F, and NOT taking temp rise during processing into considerations, 6 minutes resulted in too bit too contrasty negative and 5:36 resulted in too thin negative. Now, I'm down to adjusting process in 15 seconds increments and trying to stablize temp in 1 degree increments...

Try using 72F for a tempering water bath and a pre-wash and a processing temperature, and see how much drift you get then.

If you can get the drift down to about 3F, you can just use the mid point, and you should be fine.

Also, the difference between 5:36 and 6 should not result in thin negatives, just negatives slightly low in contrast.

Within that type of range, thin negatives can arise only from lack of exposure.

Matt

thebdt · Nov 1, 2009

tkamiya said:
Can I really do this?

Room temp for me is 82F. Extrapolating numbers in Kodak's chart, I get 315 seconds. Compensating 20% for condenser enlarger, I get 252 seconds.

That's only 4 minutes and 12 seconds....

Does anyone do this at such a high temp?

With the strength/durability of modern emulsions, 82 F is not really too warm at all. I would go for any room temp below 90 F...

BetterSense · Nov 1, 2009

I used to use room temperature, but room temperature changes around here, and I got tired of doing math every time to extrapolate times and of taking unnecessarily difficult notes. Now I do everything at 20C. I use a cut-off $1 foam cooler to hold my water bath, and cool both it and the developer with reusable ice cubes. It stays stable for 15 minutes +- 1C.

tkamiya · Nov 1, 2009

With my current process, there is simply too many variables and uncertainties. Based on my calculations, the uncertainties can easily account for as much as 10% difference in contrast. Since there may be variables within variables, the actual difference can be more. This fact alone makes all testing I've done prior to this unusable as a source of reference, unfortunately. I can guess what may have happened based on immediate 2 degree temp raise and gradual 1 degree raise, but I'd be hard pressed to call this a repeatable result.

I'm going to retest this using 75 degree reference temp, pre-wash, and temp-holding-bath, 6 minutes dev time and see what happens. My goal is to achieve anywhere from 15 to 20% reduction in contrast from Kodak's standard. These parameter should result in 15% reduction exactly.

By the way, the test I've done with 6 minutes and 5:36 dev time were done with two rolls of films taken on the same shooting session using exactly the same location and equipment. Exposure difference contributing to thin negative is unlikely, although not impossible. I'm more inclined to attribute this to uncontrolled variables during the development session. Either way, I'm going to do fresh testing with more tightly controlled environment.

Steve Smith · Nov 1, 2009

I remember Roger Hicks posting here a couple of years ago about the way he dealt with this. He would measure the developer temperature in the middle and near the end of the time, work out how much it had changed then reduce or extend the time to compensate.

Steve.

Anon Ymous · Nov 1, 2009

You can also compensate for the temperature difference by starting development at a lower temperature. In any case, I do a presoak to help get the film and tank as close as possible to the desired temperature. A water bath where you keep the tank when not agitating will also help.

Michael W · Nov 1, 2009

With daylight tanks (e.g. Paterson that I mostly use) it's easy to put the thermometer in during processing to check if the temp is stable. If it's changing it's reasonably easy to adjust to a different time.

Edwardv · Nov 2, 2009

Try a two bath developer such as Stoeckler, Vestal D-76, Barry Thornton to name a few. You can do a search on two bath developers on Apug.

Good luck.

Rick A · Nov 3, 2009

I'm a follower of the "KISS" method. Water bath to stabilize temps for all my chems, run everything at (or as close to) 20c , let everything stabilize for a few minutes, check temp, then start, keeping my thermometer in the bath tray to monitor. I toyed with the idea of a stick-on thermometer(aquarium)for my stainless tanks for awhile, might still try it just for grunts-n-grins. Anyway, throw all that crazy extrapolating out, simplify by using a standard temp and a water bath.

Rick

alexmacphee · Nov 3, 2009

Alessandro's recommendation is good, and it's how I work. Eliminates all the variables. Takes a little effort, but once you get used to the routine, it's easy. I equilibrate all the solutions in glass bottles (glass allows solutions to get to temperature easily), in a water bath in the kitchen sink, and have a bottle of water in there for a pre-soak to get the tank contents to temperature too, though that may be over-cautious.

timk · Nov 3, 2009

I usually just get everything at room temperature. So if you're mixing the developer, make sure the water you mix with is also at room temperature (you can draw a large container from the tap and leave it sit for a few hours before you start).

the stainless steel tanks are much better for heat transfer than the plastic tanks are so if you plan to have a water bath, this is preferred. Especially if doing E6 or C41 this is essential.

Usagi · Nov 3, 2009

The water bath is way to go. I need to use it during summers to cool chems down to 24°C (75°F). During winters that's about the room temperature so it's easier.
Although I would like more to go lower temps like 20°C or 22°C to get longer developing times for negatives with low contrast but I have stuck in 24°C to keep things simple.

My setup is simple. Just make sure that there's enough water so that it's temperature does not change within one hour or two...

jolefler · Nov 3, 2009

Paper trays work well....

enough for a water bath for my purposes. I rarely encounter temp drift even in a challenging environment.

Maybe it's my color processing backround, but I never do temperature/time adjustments - B&W always goes off at 68; color depends on which process, though always at manufacturer recommendation.

thebdt · Nov 3, 2009

All these water baths seem kind of wasteful. There's a reason the time-temperature charts are published by the film manufactureres like Ilford; if it weren't safe to develop film at various different temperatures, they wouldn't facilitate doing just that.

Don Wallace · Nov 3, 2009

Room temperature is a problem for me. In the summer months, it is pretty good - around 68F/20C - but in winter, it can get very cold and I have to keep a little heater going. The heater makes it liveable, but liquids tend to lose temperature quickly. For larger formats, I use a Jobo but I have not done any tests yet for roll film (pure laziness) so I still develop it an inversion tank.

I fill up a large bucket with water at 68F/20C and hold the tank in the water between inversions. The only truly critical part is development, of course, and I have found that with this method, I can keep the developer in the tank pretty much spot on the whole time.

I keep a thermometer in the bucket so that if the temperature starts to drop, I can add a bit of warm water. Experience shows just how much one needs to add. The same is true for keeping the temperature down. I mix the bucket up to the right temperature and keep a pitcher of ice water nearby. Again, knowing how much to add comes with experience.

The perfect solution is to have a darkroom built with year-round temperature control. As soon as I win the lottery, I will do that. Maybe I will even hire a cook and a few servants to wait on me while I develop.

Usagi · Nov 8, 2009

thebdt said:
All these water baths seem kind of wasteful. There's a reason the time-temperature charts are published by the film manufactureres like Ilford; if it weren't safe to develop film at various different temperatures, they wouldn't facilitate doing just that.

The time-temperature charts has one problem: They are approximations with wide error factor. The real time-temperature relation depends on developing agent and is different with varying developers.

The published general charts will give you somewhere near proper time, but they don't give precise time. If you have standardized development on 24 degree celsius and use chart (ilford for example) for developing on 20 or 26 degree celsius, you won't get indentical results.

Does it really matter, is up to everyones personal taste.

alexmacphee · Nov 8, 2009

I don't think water baths are wasteful in the slightest. Temperature charts are useful, but the issue isn't which temperature you choose, but that the chosen temperature should be constant. You have considerably more control over the temperature of a mass of water than you do of a mass of air.

Temperature change in development tank

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