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  1. #21

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    I use Joe's sandwich bag method for adjusting the temperature of print chemistry. A bag of very hot water or ice cubes dragged back and forth through the chems in a tray will raise or lower the temperature very quickly. A temperature probe placed in the tray and hooked to a digital thermometer makes the process even easier. I use a different approach with negative processing. The key to my method to temperature control is a plastic tub for a water bath, multiple 32oz stainless steel tanks for the developer, stop and fix and a 1 gallon pitcher. Depending on whether I want to raise or lower temps I fill the pitcher with ice water or the hottest tap water I can manage. Each SS tank is filled with dev, stop and fix. One by one I submerge them about half way into the pitcher while stirring the chems with a thermometer until the desired temp is reached. Again this process is very fast because the SS is such a god temp conductor. The process is made even faster because while I'm very concerned with dev temp I'm much more carefree with my stop and fix temps. Again, I agree with Joe that there is nothing magic about 68 degrees. I believe 65 to 78 should be fine with appropriate time adjustments. One last trick for monitoring print developer especially in the Winter when my DR temp can hover around 60. I'm fortunate to have a Zone VI Compensating Dev Timer. A $1.00 quartz metronome bought at a yard sale set at 60 beats per minute runs constantly in my DR. When the timer is in synch with the metronome I know I'm at 68 degrees. When the timer starts to run considerably slower than the metronome I pull out my sandwich bag of hot water and drag it through the dev tray until the two are back in synch. While this does seem to defeat the design purpose of the timer I tend to get impatient when print developing times get much longer than 2 min.

  2. #22

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    For me it is very easy to heat up chemicals. and there are many gadgets for that (tray heaters comes first on my mind). I on the other end have troubles to cool down chemicals
    Bosnia... You don't have to be crazy to live here, but it helps...
    No things in life should be left unfinis

  3. #23
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    Quote Originally Posted by bessa_L_R3a View Post
    I tried leaving my solutions at room temperature but when stuck the thermometer in, I got readings of 55 degrees, pretty chilly ...

    So now I'm trying the water bath thing. I fill up a plastic tub with warm water and stick my developer and fixer in it.

    Is this what I'm supposed to do? Then what? Wait until the chems even out with the ambient liquid temp until it cools down to 68? This could take hours.

    The other problem I'm having is that when I stick the containers with the chems into the water bath, they all start to float around chaotically. SO FRUSTRATING. I know there is some law of liquid dynamics here at play but how do I submerge everything and avoid them floating away or tipping over?
    I have a water temperature gauge that attaches to my kitchen sink (I got it a Adorama for $60) that helps me get the tap water to 68 degrees very quickly by adjusting the hot and cold. I have plastic tubing from it to the tub. However I have standardized all my process temperatures with a Weston thermometer and I found that when the gauge is at 70 degrees then my Weston reads 68. As long as you are consistent it does not matter. I run this water into the tub at a low flow rate during my processing of the film.

    I have drilled holes at the same level all the way around the tub so that the water drains at the highest level without floating the tanks. I have water that is 68 degrees in the tub at all times, it works like a charm.

  4. #24
    bessa_L_R3a's Avatar
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    thanks all for the myriad suggestions. i will certainly figure out a way that keeps me sane

  5. #25

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    Infrared and Digital Thermometers

    My grandfather used to develop his stuff in Rio with a double tray setup and ice in the outer tray. When there's a will.....

    Anyway, I bought a cheap $10 digital infrared thermometer from Harbor Freight a year or two ago. Wow! Useful for so many things, I discover new ones almost daily. I use it in auto repair, setting refrigerators and freezers, and now, the darkroom. Aim, press the button, and there's the temperature. No need for inaccurate cheapo or misadjusted thermometers, or dealing with a long stem, or just waiting for the thing to stabilize.

    And you can point it into the sky and see readings like -20 degrees. Wow, ain't the universe something?

    Also from Harbor Freight is a large digital thermometer that I can't find in their catalog anymore. It has an external (and internal) sensor at the end of a long wire. Plop it into whatever and there you are. It takes a short while to stabilize, but is good for keeping tabs on critical processes. You can probably find similar as an "inside-outside" unit for cars.

    I have a mercury filled glass lab thermometer; I have no recollection of it's stated accuracy but I take it as gospel. The above thermometer, at least the one I have reads about 1.5 degrees low. Thermometers are notoriously inaccurate as a generality. Look at any bunch in a store and they will be all over despite sitting next to one another for weeks.

    Well, dontcha know, I just checked Harbor Freight's website and my little infrared one isn't listed, but here's a $20 one, much better: http://www.harborfreight.com/cpi/cta...emnumber=93984

  6. #26
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    I also have the Harbor Freight IR unit, $19.95 as I recall and have determined it is accurate to within 1 degree at least. Couldn't you just point it at the liquid surface to determine temp?
    WYSIWYG - At least that's my goal.

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  7. #27

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    Quote Originally Posted by bobwysiwyg View Post
    I also have the Harbor Freight IR unit, $19.95 as I recall and have determined it is accurate to within 1 degree at least. Couldn't you just point it at the liquid surface to determine temp?
    That's what I do. My little cheapo unit has a wide 45 degree read pattern, so for some things you need to put it up real close or even right on the subject to be metered.

    I do just what you suggest to confirm the water temperature for mixing chemicals, for instance. I was doing some fixer formula testing the other night and was using only 100ml. A typical darkroom thermometer would not have been usable. After mixing the hypo in, I put the beaker in the freezer to get it down to room temperature. The IR thermometer was easy and quick to check the diminshing temperature.

    How did you confirm the accuracy of your unit?

  8. #28
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    Quote Originally Posted by Paul Verizzo View Post

    How did you confirm the accuracy of your unit?
    I did it a couple of ways. One was against the house thermosat, the second using a therm. used to check temps of cooking items (electronic fork thing) which has a plug in probe and finally against a Davis weather station with a +/- one degree accuracy. Matched all three and figured that was good enough for me.
    WYSIWYG - At least that's my goal.

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  9. #29

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    Quote Originally Posted by bobwysiwyg View Post
    I did it a couple of ways. One was against the house thermosat, the second using a therm. used to check temps of cooking items (electronic fork thing) which has a plug in probe and finally against a Davis weather station with a +/- one degree accuracy. Matched all three and figured that was good enough for me.
    Great. Yeah, ultimately it's only critical on development and one should work the developing time to the thermometer, not the other way around.

    I'm sure you realize that anything +/- 1 degree could be off as much as two degrees when you are dealing with two units. But, hey, we aren't doing qualitative analysis of biochems here.....

  10. #30
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    You raised a couple of good points. First being my poor choice of words. Actually the Davis instrument claims accuracy 'within one degree.' All three displayed accuracy well within my humble needs.
    WYSIWYG - At least that's my goal.

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