Precision cookers and C-41 chemicals....

Discussion in 'Color: Film, Paper, and Chemistry' started by sperera, Jan 3, 2018.

  1. sperera

    sperera Subscriber

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    Happy New Year to everyone....

    In my wisdom (or lack of) I thought I'd purchase a liquid temperature regulator in the form of the following item.....to use in a water bath situation as depicted (image shows water inside the graduates for purposes of this thread)

    I bought this:
    https://anovaculinary.com/anova-pre...MIlPXE64e82AIVRrobCh0SogeIEAAYASAAEgK0U_D_BwE

    Now the problem I have is it heats up the water temperature in the 'water bath' to the required 38 degrees centigrade easily and fast but the liquids inside the Paterson plastic graduates (as they call them) are way lower temperature.....

    What should I do:
    1. Find what outside water temp makes liquids inside 38 degrees OR
    2. Just wait cos the temp inside the graduates will come up to the temperature of the outside water in xx amount of time????

    This is a thermodynamics question of course......
    Any advice more than welcome......
     
    Last edited: Jan 3, 2018
  2. OP
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    sperera

    sperera Subscriber

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    c41_temp.jpg here's the set up....as I said....just water for test purposes.....
     
  3. Wallendo

    Wallendo Subscriber

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    The problem I see with this set-up is that your cylinders show half of your chemicals in the water bath, and the other half above water level and therefore exposed to room temperature. You will need either a deeper pot, or wider shorter cannisters.

    The other option is to set to tremperature to a higher setting and stir the chemical well.
     
  4. OP
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    sperera

    sperera Subscriber

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    thanks for the reply.....so the answer is total immersion?
     
  5. darkroommike

    darkroommike Subscriber

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    You just wait, but you can start with slightly warmer water in a tub to prewarm the bottles while the sous vide is coming up to temp.
     
  6. Chan Tran

    Chan Tran Member

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    I would use something heavier and conduct heat better like stainless steel container. That way the chemical can be fully underwater yet the container doesn't float. Use a second thermometer like you do to make sure the chemicals up to temp before use. I still have problem that the chemicals cools during processing though.
     
  7. trendland

    trendland Member

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    The best should be to overtemperate the baths.
    Then messurement with thermomether will give you the starting point for developement if your (lower) temperature is reached.
    with regards
     
  8. OP
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    sperera

    sperera Subscriber

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    thanks for your replies......
     
  9. bernard_L

    bernard_L Member

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    Not ! If you do that you lose the benefit of a regulated water bath. There is no fixed offset between the bath and the liquid inside the Paterson graduates.
    Yes! BTW, stainless steel is maybe a better conductor than plastic, but a poor conductor amongst metals. Pure metals (copper, aluminum) are better heat conductors (which is why SS pans have a copper layer sandwiched at the bottom) but may have corrosion issues.

    My suggestion would be a thin-walled glass container; Check with lab supplies, Bechers or Erlenmeyers.
    http://www.laboandco.com/verrerie-consommable/becher.html
    http://www.laboandco.com/verrerie-consommable/fiole-erlenmeyer-1.html
    https://www.lelaborantin.com/produits/verrerie-usuelle/bechers.html
    https://www.lelaborantin.com/produits/verrerie-usuelle/erlenmeyers.html
    These link to suppliers in France... only because my search engine is aware of my location. But since lab suppliers might be scarce in Gibraltar, you may have to resort to international shipping anyway.
     
  10. OP
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    sperera

    sperera Subscriber

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    fantastic responses thanks!!!!!!!!! and yes im in the wilderness here
     
  11. Chan Tran

    Chan Tran Member

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    I used glass before but they are not very good heat conductor. Copper is no good as it would react to the chemicals.
     
  12. trendland

    trendland Member

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  13. WilmarcoImaging

    WilmarcoImaging Member

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    A regulated bath is not strictly necessary. A bath that does not lose its temperature quickly is necessary, or at minimum very helpful.

    Preheating the film and processing hardware (tank) helps with temperature control. I do this with a plain water pre-wet bath at 100 deg F.

    The time required to hold accurate temperature is short - 3 minutes and 15 seconds to be exact. The tempering bath doesn’t need to be any more sophisticated than needed for this short time period. The subsequent steps have a larger window of acceptable temperature.

    Large thermal mass = a good thing. I see a small thermal mass in the photo above. Larger water volume = larger thermal mass. Near total immersion is helpful to achieve initial temperature. Not strictly required during processing.

    Slight tempering bath overtemperature of 5-10 degrees is useful. A non regulated bath loses temperature from the moment the hot water supply is turned off. This is no problem if the bath is large enough (mass, volume) and insulated.

    Try using a picnic cooler as the tempering bath. 30 liters of water at 105-110 deg will do nicely. After coming up to temp drain the excess water until the tank can be settled in the bath without submerging it. This system brings the chems to temp in 5 minutes and holds accurate temp for prescribed time.

    Glass or steel vessels are not necessary. Nice to have, but not necessary.
     
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  15. dabsond

    dabsond Subscriber

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    Santa Claus brought me one of these for Christmas as well. I use the 1 quart brown bottles for my C41 chemicals. I purchased a large tub where the water level comes up to just below the neck of the bottles. I set it for 104F and let it get up to temperature. It takes about an additional 35-40 minutes for the chemicals to get up to and hold at 102F. Nice to set it and forget it while loading spools etc.
     
  16. trendland

    trendland Member

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    A bath that does not lose its temperature quickly is necessary, or at minimum very helpful.

    Preheating the film and processing hardware (tank) helps with temperature control. I do this with a plain water pre-wet bath at 100 deg F.

    The time required to hold accurate temperature is short - 3 minutes and 15 seconds to be exact. The tempering bath doesn’t need to be any more sophisticated than needed for this short time period. The subsequent steps have a larger window of acceptable temperature.

    Large thermal mass = a good thing. I see a small thermal mass in the photo above. Larger e from the moment the hot water supply is turned off. This is no problem if the bath is large enough (mass, volume) and insulated.

    So you just remember the function from
    chem lessions ?

    Temperatur cooled down a couple degrees within a special time.
    To reach the next step the temperature goes with the half down as before (within the same time) so you have to double and double the time again and again.
    Theoratecally the temperature of stuff (concerning on the volume also) will never reach its ambient temperature.

    with regards
     
  17. trendland

    trendland Member

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    Sorry reply function failed!
     
  18. trendland

    trendland Member

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    I refered to you Wilmarco Imaging - don't intend to copy your text sorry.

    with regards
     
  19. Old-N-Feeble

    Old-N-Feeble Subscriber

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    +1
     
    Last edited: Jan 3, 2018
  20. Old-N-Feeble

    Old-N-Feeble Subscriber

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    +1
     
  21. Old-N-Feeble

    Old-N-Feeble Subscriber

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    +1

    Also, float a piece of flat styrofoam atop the water bath with holes cut for the containers to poke through. This nearly eliminates cooling via evaporation. Make sure to avoid little bits of styrofoam from breaking off in the bath... lightly melt the cut areas to prevent the remaining material from flaking off... but don't start a fire doing so... flameless heat.
     
    Last edited: Jan 3, 2018
  22. bernard_L

    bernard_L Member

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    Agreed.
    I proposed glass because, being faced with the same issue (poor thermal contact through a Paterson graduate), I found more easily containers of the desired size in glass than in stainless steel.And indeed the situation improved.
    Thermal conductivities are (units W/°C/m):
    So Pyrex is 7x better than polystyrene, and stainless steel 16x again better. Beyond a certain (TBD?) point, the vessel's conductivity ceases to be a major factor.
     
  23. WilmarcoImaging

    WilmarcoImaging Member

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    Trendland yes I agree that temperature drop follows a decay (diffusion) law, which is also related to mass. Mass includes the tempering water and any vessels used to hold the chemicals.

    sperera one suggestion to your system is to use an insulated box to hold the tempering water. This would make the job easier for the temperature controller.
     
  24. bvy

    bvy Subscriber

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    Agree. This is overkill. You need to maintain the tank temperature of one bath for three minutes. The other baths can drift. A hot water bath in a small cooler is sufficient to accomplish this. Do some "dry runs" -- tank with empty reels, water as developer, and otherwise proceed as if you were developing film. Probe the temperature of the developer (water) going in and coming out of the tank. For my purposes, I want 101F going in and 99F coming out (allowing for a one degree drop with each pour). Note the water bath temperature and volume that accomplishes this. Also note the room temperature if your workspace is prone to wild fluctuations. Re-test periodically.

    As far as the water bath to heat the chemicals, I couldn't care less. I dump hot water in the cooler with all my bottles and monitor the developer temperature. The other solutions will be close enough, and, as I mentioned, they'll drift down gradually at a rate that won't harm your film (i.e. don't pull bleach right out of a fridge and dump it in).
     
  25. OP
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    sperera

    sperera Subscriber

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    excellent help thanks so much
     
  26. WilmarcoImaging

    WilmarcoImaging Member

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    Agree with this.
     
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