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Thread: Temperature Control

  1. #1

    Join Date
    Sep 2006
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    Temperature Control

    I am new to Large Format but have been doing 35mm and medium format for some time. Since I now have control of individual negative development I want to closely control the temperature during development. My house water is not cold enough to use to bring the temperature down to the right temperature. I have tried ice water baths but that is too unstable.
    Has any one encountered and solved this problem?

    Thanks

  2. #2

    Join Date
    Feb 2005
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    2,955

    Re: Temperature Control

    I hand-roll a Jobo 3006 Expert drum on the $20 Jobo roller base.

    In summer I crank-up the aircon, put the Jobo in the fridge briefly, and cool the developer in an ice bath to one degree less than my desired development temperature. By the end of the development time the developer temp is one degree above (I tested this previously, depends on ambient temp.) so the average temp. is what I require.

    I could alternatively get stronge aircon that would maintain the air temp at 68, or I could use a higher temp. with a shorter development time. But I prefer not to re-test, and so I stick with the same time.

  3. #3

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    Re: Temperature Control

    "My house water is not cold enough to use to bring the temperature down to the right temperature."

    There actually is no "right temperature." While Kodak and maybe other companies specified their times at 68 degrees, it isn't necessary to process at that temperature. You can just as good results at higher temperatures. It's much more important to test and consistently process at the same temperature no matter what it is (within reason of course) than it is to process at 68 degrees. So I wouldn't worry about using ice to bring the temperature down, pick a temperature that is convenient for your situation, test on the basis of that temperature, and use it for all your processing.
    Brian Ellis
    Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
    a mile away and you'll have their shoes.

  4. #4

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    Re: Temperature Control

    Brian's answer is right on. If your cold water is higher than 68 degrees F consistent, (say, 74 degrees F) just use that temperature as your standard. You just need to find the appropriately shorter time for the higher temperature. Most modern films can be processed at up to 80 degrees F.

    Here is a link to the Ilford temperature conversion chart to help you get started.

    http://ilford.com/html/us_english/pdf/tempconv.pdf

    However, the above chart is not completely accurate for all developers. I'll take the liberty of quoting David Carper from his response in another forum regarding the Ilford Chart (David worked in the technical dept of Ilford for years and is an authority).

    "The tables are based on the combination of ID-11 and FP3 (!). They work quite well with ID-11 and any film; and also work quite well with some other developers, including I think HC110. But some modern developers such as XTol, TMax, or ILFOTEC DD-X do not show the same change in activity with a change in temperature; if you use the chart for these developers, you'll likely end up with underdeveloped negs at higher temperatures. In the last few years, an attempt was made to move away from the charts, and testing was conducted at both 68 and 75 degrees on new films, but the resources were not available to fully test all films at both temperatures. If you are using Delta 400 or 3200, use the times listed in the box; for intermediate temperatures, you can get a pretty good time by extrapolating in a straight line; the variation isn't enough to mess up anything short of scientific work.

    If you're using a modern developer and other films, do a little testing. IIRC, for these developers, the chart showed about an extra 50% change over what was really required; so if it calls for 30% less time, test at 20% (but do a test; I'm working from memory here)."

    You can find the entire thread at

    http://photo.net/bboard/q-and-a-fetc...id=00Ak5S&tag=


    Hope this helps a bit.

    Best,
    Last edited by Doremus Scudder; 15-Sep-2006 at 23:58.

  5. #5

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    Re: Temperature Control

    I live in Richmond, VA and the tap water can be 75 degrees easily during the summer months. I usually try and aviod the darkroom during the summer, but I have found the Zone VI compensating developing timer to be a god send. This timer has a probe that goes into your developer tray (I use tray development) and automatically adjusts the time (faster or slower) as the temperature of the developer changes. I use Pyrocat-HD and the time for my Tmax-400 negatives is 16.5 minutes @ 68 degrees. With my hands in the developer for 16.5 minutes, the temperature rises a few degrees during a normal developing session. The timer speeds up as development progresses and my "16.5" minutes is usually somewhere close to 13-14 minutes of actual time.

    This timer has a switch so you can adjust the time for either films or paper. The built in curves were originally programmed for Tri-X and HC-110 dil b and Zone VI brilliant developed in Dektol. I have found that the time/temperature curves for most other films and papers benefit from this compensating timer.

    These can be found used on Ebay. I think Calumet stopped manufacturing new ones about two years ago. I have one that is about 15 years old and purchased one of the last new ones Calumet sold so that I would have a back-up should the first one die. I would encourage you to call Calumet if you are interested in one of these. They may still have a few new ones lying around, and the used ones go for almost as much as Zone VI sold them for new 15 years ago.

    Good luck,

    John

  6. #6

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    Re: Temperature Control

    eBay prices for the Zone VI Compensating timer have often EXCEEDED what they sold for new 15 years ago (which, if memory serves, was around $400). I baby mine (my second, after my first got zapped when lightning hit our house), and you would have to pry it from my cold, dead hands. It is one of the great inventions of photography.

    And while Picker calibrated it for Tri-X and HC-110 for film, and Brilliant and Dektol for paper, it will get you far closer to accuracy with any other combination than nothing.
    Bruce Barlow
    author of "Finely Focused" and "Exercises in Photographic Composition"
    www.brucewbarlow.com

  7. #7
    Jim Jones's Avatar
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    Re: Temperature Control

    I tray to maintain the temperature of the darkroom between 68 and 75 degrees. Chemicals, tanks, and wash water are stored in the darkroom, and should stabilize at a practical temperature. Developing time is adjusted to accomodate the ambient temperature.

  8. #8
    Abuser of God's Sunlight
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    Re: Temperature Control

    I'm not a fan of compensating timers, because in addition to costing a lot, they assume that all developers respond the same way to temperature. Which isn't the case. Hydroquinone is much more temperature sensitive than metol, for example. It has a steeper activity/temperature curve, and actually becomes innactive below 64 degrees or so. So a developer with a higher proportion of HQ to metol will respond to temp changes differently one with a lower proportion. And very differently from a metol only developer. And this is just one example using a couple of the most popular developing agents.

    If you're going to compensate, it's best to test your individual developers at a few different temps, and write down the results.

    Since I've always had darkrooms with huge temperature swings from season to season, I find it easier to just do it all at 68. Hot water bath in the winter, ice water in the summer. It's second nature ... easy to keep everything within a half a degree, no matter lattitude it feels like in the room.

  9. #9

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    Sep 2006
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    Re: Temperature Control

    Thanks for the helpful hints.
    I'll look for the Zone VI Timer and I will use the temperature conversion chart.

    Mickey

  10. #10

    Join Date
    Sep 2006
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    15

    Re: Temperature Control

    I wonder if those of us with Zone VI compensating timers could work together to develop a set of tests for other common chemistries besides HC 110 and Zone VI Print Developer so that we could do better than just guess that the device works better than nothing with other formulations.

    Where would one start? Was Paul Horowitz involved with designing this product?

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