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Heroique
20-Apr-2011, 10:05
The chart below might surprise you if you’re tray developer.

From a related thread, Steve Gledhill’s chart shows a significant increase in temperature of the developer solution (800 ml) during tray development – more specifically, a 2.5 C jump after 7 minutes, and a 4 C jump after 15 minutes. These changes are typically due, I suspect, to a combination of using the hands; the air temperature (if warm enough); and the heat-producing chemical reaction itself.

Put more simply – it shows the developer solution’s average temperature is significantly higher at the end of the development step, than it was at the beginning.

So that leads me to a few questions…

1) Do you account for such changes when you “choose” a development temperature? Or, do you simply repeat the process that gives satisfactory results, and worry less than others about possible temperature changes?

2) If you use a technique to keep temperatures constant (such as rubber gloves, slosher trays, water baths, etc.), have you actually tested the effectiveness?

3) And, if your darkroom’s air temperature is different from session to session (say, winter vs. summer), might this influence the “slope” of the developer’s temperature line (for example, steepen it), causing inconsistent results & splitting headaches?

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What’s your personal experience? Can you share tips or insights about this?

Scott Walker
20-Apr-2011, 10:33
I use a water bath, my sink has a fairly large basin and is ribbed so that there is 1 inch of water in the sink before it can even touch the trays and the bottom of the trays are also ribbed giving a bit more surface area. I normaly have about 2 inches of water in the sink and have tested the developer temp after developing once the film is in the fix and found no variation

Pic of my sink
http://i246.photobucket.com/albums/gg90/Beecool/IMG_4739copy.jpg

Nathan Potter
20-Apr-2011, 10:43
Any tray development I do is at the darkroom air temperature and with forceps to handle the film, unless the tray is water jacketed. But by choosing special developer techniques for B&W it is possible to reduce or even eliminate the effect of temperature variations. Color processing is another matter altogether where it is essential to keep the temperature within +/- 1 degree or better.

In the south, at high ambient temperature, the temperature rise can be even more dramatic than on the graph shown. For color work when the bath water comes in at 85 degrees F, or higher, I use a peltier 600 watt cooler run by a 15 amp DC supply to cool the bath water for a rotating drum.

Nate Potter, Austin TX.

Mark Sampson
20-Apr-2011, 13:33
Anecdotal experience here. I process 4x5 b/w using 2 liters of developer in an 8x10 tray, agitating 6-12 sheets by shuffling them. Not long ago, while setting up a processing run, I decided to see how much the presence of my (gloved) hands in the tray affected the temperature. So as soon as the film went into the fixer, I went white-light and put the thermometer back in the tray. After 10 minutes of developing, the developer in the tray had gone from 68F to 68.5F. The room temperature was probably around 66F. So... for me, the variation is not enough to worry about. Of course, when I tested for my process time, the same conditions were in effect; so the minor dev-temp variation was accounted for right there.

paulr
20-Apr-2011, 13:44
For film I anal-retentively control temperatures with water baths. All the way through from presoak to wash.

With paper I let the chemicals do what they will, but I watch the temperature and adjust the time in each developer accordingly. Different developer agents respond differently (metol is more temperature sensitive than hydroquinone, for example), so I graphed the responses of the developers I use and consult them for final times. The difference is often unnoticeable in the freshly developed print, but makes a big difference in how the print tones in the toners I use.

The only caveat is that I can't develop when things get really cold ... metol becomes more or less inactive below 65. And that's warm for my place in the winter.

Harold_4074
20-Apr-2011, 13:45
In my case, the opposite occurs, although I haven't taken the data for a graph. The humidity is normally low enough that that any solution in an open tray will drop several degrees in fifteen minutes. (I agitate by tilting the tray, so my hands aren't in the solution that much.)

At 35% relative humidity and 25 C in the room, the equilibrium water temperature would be something like 15 C, although the air circulation rate isn't high enough to get it that far down.

paulr
20-Apr-2011, 15:04
In my case, the opposite occurs, although I haven't taken the data for a graph. The humidity is normally low enough that that any solution in an open tray will drop several degrees in fifteen minutes.

That's been my experience, too. Solutions get cooler than the air in the room. I've never figured out what caused it. I've lived in pretty humid places so it doesn't seem like that would be the only factor.

Heroique
20-Apr-2011, 15:17
...The humidity is normally low enough that that any solution in an open tray will drop several degrees in fifteen minutes...


That's been my experience, too...

Harold’s remark about low humidity is quite interesting. Could low-enough humidity be causing a quick enough evaporation of the solution to reduce its temperature? Maybe the low humidity sloughs off the hottest molecules from the solution’s surface – like blowing on your porridge...

Drew Wiley
20-Apr-2011, 15:21
I use thin dimple-bottomed stainless steel trays for film development. Around this is a
substantial water jacket. For critical work this is hooked to a thermoregulator which
keeps the bath within 1/10 degree F! For more ordinary work or simple black and white
print development, I just use the Zone VI compensating development timer. My sink room has R23 insulation around it, so stays very stable in terms of room temperature.
This only changes significantly when the air exchanger is turned on. On especially cold
days I will use a small Intertherm style heater to bring up the ambient air temp in advance of my work session. Usually I try not to keep my fingers in the developer for
longer than necessary. I don't know exactly how to factor this in, but the water bath
seems to do its thing, and densitometer measurements with step tablet tests etc show
that my temp controls are extremely effective when a high level of precision is called for. For just ordinary Zone system work and general photography I simply use the
drift by system with the water Jacket and Zone VI timer, and this is plenty good. The
key is to have sensible ambient room temperature and a lot of water volume in the
jacket or surrounding larger tray.

Leonard Peterson
20-Apr-2011, 15:43
Or use Fred Pickers Zone VI film developer timer which adjusts for temp change. This has been out since the 1980s and works well. Problem solved and you don't have to worry or think about this issue anymore. Usually available on ebay.

John Bowen
20-Apr-2011, 16:43
Or use Fred Pickers Zone VI film developer timer which adjusts for temp change. This has been out since the 1980s and works well. Problem solved and you don't have to worry or think about this issue anymore. Usually available on ebay.

+1. To quote my god friend Bruce Barlow, "you will have to pry mine from my cold, dead hand."

Andrew O'Neill
20-Apr-2011, 17:03
When I tray develop, I do one sheet at a time. My fingers don't go in the developer, so no worries about temperature change.

Michael Kadillak
20-Apr-2011, 17:15
If your darkroom is in the basement (like mine) where the temperature is cool but consistent and one follows the same procedure in their tray development, any increases in temps would be consistent and easily accommodated in the results. I do not see any problems at all.

BetterSense
20-Apr-2011, 17:36
I don't care. I don't do anything special to compensate, no water baths or anything, and my negatives come out fine, so I'm not worried. I'm not trying to reproduce a contrast chart or anything. In the summer I do have to cool the developer with ice. I was going to use a peltier element to make a temperature regulating water bath, but the project died.

Heroique
20-Apr-2011, 18:06
To quote my good friend Bruce Barlow, “you will have to pry mine from my cold, dead hand.”

Here’s the “cold, dead hand” Thread (http://www.largeformatphotography.info/forum/showthread.php?t=31455) covering the fundamentals of the Zone VI timer – whose Einstein-like “distortion” of time seems to reduce the guess work about solution temperatures & development times.

Its best critics explain that its “benchmark” is (old) Tri-x + HC-110 (sol. B) at 68 F (or if paper, w/ Brilliant + Dektol) which may be reason for concern, esp. if you’re working w/ uncommonly warm or cool temperatures where film curves can differ a lot. Its eloquent advocates reply that it’s close enough for most film/developer combos at normal temperatures – including the ever-fickle T-Max.

I’m still a little curious how the tool might interpret a changing temperature…

Drew Wiley
20-Apr-2011, 20:00
The Zone VI gadget does in fact work as claimed, even though I was often personally annoyed by Fred Picker's snake-oil salesmanship style. I used this device
for many years for both film and black-and-white paper development. No, it's not
really good enough for extremely fussy tasks like color separation negs from T-Max
or critical color mask densities. It's based on 20C and can't be recalibrated for significantly elevated standard temperatures. Won't work for color chemistry. But it makes just about everything else a lot easier and predictable.

ic-racer
20-Apr-2011, 20:35
Someone has got warm hands :)
Has anyone been able to reproduce these results?

Bill Burk
20-Apr-2011, 20:55
I hope you take the opportunity to notice how much slower time passes as you pry the CompnTemp probe from my cold, dead hand.

Heroique
20-Apr-2011, 21:10
Someone has got warm hands :)
Has anyone been able to reproduce these results?

When I’m using hands, I get similar results, though not quite as dramatic as Steve’s. However, I do cool my fingers w/ ice water per AA’s The Negative & use a water jacket. Even with slosher trays, my results are heated. I think what may be a key cause of rising heat is the heat-producing, silver-halide into metallic-silver chemical reaction. Its influence on temperature probably varies according to one’s emulsion/developer combo, the total volume of solution, and all the other variables. BTW, one advantage of my rainy part of the world – no worries about low humidity & the way it apparently cools the developer!


I hope you take the opportunity to notice how much slower time passes as you pry the CompnTemp probe from my cold, dead hand.

In this case, the Zone VI timer would indicate “Eternity.”

Bill Burk
20-Apr-2011, 23:08
Heroique,

To get back to your original question, the legacy Zone VI compensating developing timer and the currently available CompnTemp timers adjust the time continuously with the change in temperature.

They cancel out the effect of fluctuating temperature in real-time.

Doremus Scudder
21-Apr-2011, 00:59
Repeatability, repeatability, repeatability. If you do everything the same way every time, you will include all the variations in temperature, evaporation, etc. If you test to the method, you will have predictable results (within working parameters, of course).

It is quite possible that the temperature of the developer solution rises a bit due to heat from my hands, but if that is a constant, then I don't have to worry about it, just repeat it. It is also possible that evaporation cools the solution somewhat. Unless the relative humidity where I work changes significantly, however, the effect should also be similar each time and, therefore, negligible.

The trick is to try to keep the conditions the same from day to day. So, hot summer darkrooms vs. cold winter ones are a problem for some, I imagine. I'm lucky enough that I can keep my ambient air temps between 20 and 24C most of the time. (A climate-controlled darkroom would be a great thing to have, though.)

In my U.S. darkroom, I use a Zone VI compensating developing timer. It works well, changing the time as temperature varies. However, I notice this most when printing in the summer, when the print developer temperature rises considerably over a session.

When developing film, even in the summer, the temperature rise is much less, since the developer gets mixed right before use, sits in a tray inside a larger tray with the same temperature water in it, and only gets used once. 18 minutes tops (and that's for N+3, which I don't need that much). In Vienna, I just use a simple timer and make sure to try to develop when my ambient temperature is as close to the processing temperature as possible. Again, a water-bath tray is used.

The difference in temperature rise for a liter of solution over 15 minutes in ambient temperatures of 20 and 24C is negligible. Let's say, for a 15-minute development time at an ambient temperature of 21C, that the rise in the developer temperature due to hand-heat is indeed 4C as Steve Gledhill states (and I might question that result... and, a water-bath must attenuate this effect by quite a bit). Now repeat this at an ambient temperature of 24C. How much more will the temperature rise?

Here's my test: Ambient temperature, 21C. I filled a room-temperature tray with 500ml of 14C tap water, set it on the kitchen counter without a water-bath and let it sit for 20 minutes exactly. I swished my hand in it once every minute just for good measure (although I was not testing the effect of hand-heat, I did think that agitation should be approximated in the test. However, by doing this, I probably introduced some hand-heat). The beginning temperature difference was 7C After 20 minutes, the temperature of the solution had risen to 15.2C; a temperature increase of 1.2. This without water-bath and using room-temperature vessels to measure and pour into. The effect of a 4 difference in ambient temperature would be significantly less over this time period, plus developing times are usually less than 20 minutes.

I would estimate that change from a 4C difference in ambient temp over a 15-minute developing time would be right around 0.5C (or less), i.e., significantly less than a 5% increase in development according to my temperature-compensation chart. The question is, is this within working parameters? I suspect so, for most of us shooting black-and-white film.

Bottom line, be repeatable, be repeatable, be repeatable...

Best,

Doremus Scudder

Heroique
21-Apr-2011, 13:26
These are splendid experimental insights – I suspect even the best darkroom scientists fail to consider them when aims or conditions warrant.

I noticed that no film was cooking in your personal test (as it was in Steve’s), eliminating the possibility of any heat-producing chemical reaction adding “kick” to your thermometer – especially w/ a volume of 500 ml. I’m curious if readings might have been different when processing, say, a 4x5 sheet? A small stack of them? What about a different emulsion/developer? I’m also curious if you think these considerations might be more significant in Vienna, where you have no Zone VI timer to compensate for them.

Thanks for being our careful, white-coated scientist!

jeroldharter
21-Apr-2011, 14:15
I don't use trays. I use a Jobo drum on a roller base. But I still have the same temperature fluctuation issues.

I calibrated my development times with solutions in a water bath at 68 degrees, pre-tempering the plastic drum in 68 degree water, and with an ambient room temp of 68 degrees. Now, I keep my solutions in a tempered water bath at 68 degrees and just pour them in the drum. In a second Jobo plastic drum base, I add a liter of the same tempered water in which is the temperature probe for the RH Designs Processmaster timer which works like the Zone VI. So any fluctuation in water temp inside the processing drum should be simulated in the second drum base and compensated by the temperature probe. It seems to work very well. No problems with inconsistency.

Thebes
21-Apr-2011, 19:05
I've never measured it, but my developer becomes noticeably warmer when I tray process, more so for 4x5 than 8x10. It stands to reason that this is reasonably repeatable so it should be controlled by your calibration... at least it should be repeatable if room temp, chem temp and volume, and your technique are the same each time... my life isn't so ordered.

I don't worry about it though, recently I've been developing in tray by inspection. I have sometimes worried about my (water) stop being colder enough to reticulate, this has never happened, but it feels considerably colder when I put films into it

Jim Fitzgerald
21-Apr-2011, 20:55
I use trays for 11x14, 8x20 and 14x17 in Pyrocat-HD. I DBI so no problem at all. I can see when it is done!

Bill Poole
21-Apr-2011, 21:27
I have an 8X10 tray that I have divided down the middle and use to do 2 5x7 sheets at once. I agitate by rocking the tray gently and pretty much continuously. Whether the temperature goes up or down depends on the ambient temperature in the bathroom -- er, darkroom. In the winter, my home temperature usually runs a few degrees lower than 20 degrees C, so I expect the temperature to drop. So I use standard electric heating pad under the developing tray, wrapped in plastic and with about ten sheets of newspaper between the plastic and the tray. I warm up the tray a little before I put in the developer. I usually turn the heater off about half way through the run. Seems to keep the temperature at 20 degrees average +/- a few tenths. Not elegant, but neither am I.

Doremus Scudder
23-Apr-2011, 03:46
Heroique,

My test was not to measure how much heat either hands or chemical reactions added or subtracted from the solution, rather to get an idea of how much a different ambient temperature affected the entire process. From my down-and-dirty test, I think any change due to ambient temperatures being +/- 5C from the temperature of the developer is negligible.

That means, if you do everything the same way every time, regardless of whether you get or lose heat from hands, chemical reactions, evaporation, etc., etc., you will have repeatable results, since whatever variations in temperature are repeated every time. In the end, that's all that interests me.

If I test for film speed and development time, and use the same technique each time for each different development, I'll be well within my working parameters.

One note on the Zone VI compensating developing timer: If you use one, and the developer temp does rise during the course of development, then the indicated developing time on the timer will really be shorter than the actual time due to the shortening of "seconds" by the timer as the temperature rises above the standard.

If you test with the compensating timer and then develop your negs at that same "time" with a regular timer or clock, you will likely be developing longer. This is why I have different developing times for Vienna, where I develop with a regular timer (or a metronome sometimes) and Oregon, where my compensating timer lives. FYI, the times are about 5-7% different. Water hardness also plays a role in that figure as well.

I'm quite confident I'm getting repeatable results developing with or without my compensating timer; even more so now that I've done the quick ambient temperature test. That is for black-and-white negs tray developed. If I were doing color, I would probably want more control.

Best,

Doremus Scudder

Bruce Barlow
23-Apr-2011, 03:57
+1. To quote my god friend Bruce Barlow, "you will have to pry mine from my cold, dead hand."

I think I like being a "god friend." Shouldn't it be capitalized?

Yup, Compensating Timer. For printing, I even put the developer tray in a warm water bath, just to speed things up. Wouldn't do that with negs for fear of reticulation, but prints seem to be just fine.

Heroique
23-Apr-2011, 06:46
...I use standard electric heating pad under the developing tray...

Now I know what “cooking the film” really means!

I’ve been surprised how many people see falling temperatures in their developer solution – the “evaporation effect” was a noteworthy surprise – and it’s interesting to learn how they keep the thermometer “up” or rely on a means of compensation.

Bob Farr
23-Apr-2011, 09:16
Hi,
Have read these posts with great interest and thanks to those of you who have gone through the testing procedures. I have been using a Zone VI compensating developing timer for years for paper and film. Have not noticed a problem using it.

Am wondering if anyone has tried the RH Designs version??

Bob

mandoman7
23-Apr-2011, 09:56
Its not just trays that have the problem of drifting temperature during development. Daylight tanks will drift, along with anything else that's not in a controlled bath. I found the answer to be a matter of checking at the end of processing, if the air temperature is different than the processing temp (or warm hands are in the solution). If there's much wander, the median temperature is a fairly reliable reference point for your development time, although I still always use larger trays for temperature restraining out of habit.

Brian Ellis
23-Apr-2011, 10:11
I used the BTZS tubes for many years to develop film. The tubes were in a water jacket and obviously my hands never touched the developer (though they did touch the tubes as I rotated them in the water jacket). I had an air conditioning system that kept the darkroom around 70 degrees and in Florida heating the darkroom was unnecessary. I started out with water in the water jacket at two degrees below the developer temperature. I put ice cubes in the water jacket to keep the water temperature from increasing. I didn't measure humidity but I'd assume it was pretty low because of the air conditioning unit. Nevertheless, despite all of these efforts in the course of about 8 minutes development time on average the temperature of the developer at the end was always about 2 degrees warmer than when I started. Fortunately this increase was consistent so it was factored into my tested times for normal, plus, and minus development.

I used the Zone VI compensating developing timer for prints but not for film except when I used to tray develop 8x10 film. Zone VI Studios said it could be used with film in tanks or tubes by using the timer to measure the temperature of the water in a water jacket. I was never sufficiently confident that the water temperature translated to the developer temperature accurately and consistently enough to try it.

Curt Palm
23-Apr-2011, 10:40
Full disclosure: I wrote and sell the CompnTemp software

CompnTemp is a software version of a compensating developing timer. It uses a USB temperature probe. It offers several improvements over the zoneVI timer.

-Displays the current temperature. (F or C)
-User can set the target temperature.
-both real time and compensated time are displayed.
-custom compensation curves can be added and used.
-countdown or count up timer modes.
-customizable interval tone