sodium carbonate in Pyrocat-HD

Discussion in 'B&W: Film, Paper, Chemistry' started by lee, Aug 15, 2004.

  1. lee

    lee Member

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    Sandy or any other expert,
    I have been developing in Pyrocat-HD and using sodium carbonate per Don Miller's instructions. I am mixing it 1:5:100 for silver and 2:10:100 for alt and Azo. What I am seeing is a drop in temp from when I start the development and I am wondering if the carbonate is causing this and if that is the case how can I account for it in my timing?

    thanks,
    lee\c
     
  2. sanking

    sanking Member

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    I have not used sodium carbonate in the Pyrocat-HD formula for several years but when I was using it I never noticed any drop in temperature, and don't know of any reason why that should happen.

    But it sure seems very odd to me that the temperature of the solution would drop in Forth Worth during the summer.

    What kind of temperature drop are you experiencing?

    Sandy
     
  3. Jorge

    Jorge Inactive

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    Lee, dissolving sodium carbonate in water is an exothermic reaction. It generates heat and heats up the carbonate solution. Since you are using 5 parts per 100, this might be enough to raise the temperature of the entire developer a few degrees. As you start developing you will experience a drop in temperature if you just mixed the carbonate and used it immediately.

    Hope this helped.
     
  4. lee

    lee Member

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    Jorge,
    thanks I seem to remember that from some other site I think. I mixed the part a and part b several days ago. When I am ready to develop film I am aiming for Azo so according to directions I mix in the 2:10:100. Tray developing. I measure out 20 ml of Part A and 100 ml of Part B and 1000 ml of h2o This is at 78f or so (I have a zone 6 compensating timer) This gets poured into one tray and off we go. I measured the temp after the first run of film and the temp was about 74f. So, is that what is going on?

    lee\c
     
  5. Jorge

    Jorge Inactive

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    Nope, the solution is being cooled down to your normal room temp. 78 ºF is somewhat hot to start, I am not surprised your final temp is 74º, you are probably running your house AC at about 68 to 70 ºF. I dont see the problem. Besides what do you care? that is what the Zone VI compensating timer is for. I have one and dont worry about the temp.

    OTOH if you are really getting annoyed by this, a water jacket should do the trick.
     
  6. lee

    lee Member

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    the room is about 75f so that may be it. I just was shocked to see the temp be that far low after 12 minutes or so.

    thanks and see ya next week in Mexico

    lee\c
     
  7. Donald Miller

    Donald Miller Member

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    My summer temp developer temp is about 74 degrees...winter temp is 70 degrees in the tempered water bath...with the Zone VI comp timer that is close enough for what I do.
     
  8. lee

    lee Member

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    thanks don I am gonna call JandC tomorrow and order a box of Efke 100 I just don't have any faith in the TMY

    lee\c
     
  9. photomc

    photomc Member

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    Lee, Jorge, Donald et al,,,,so how does a comp. timer work? Do you input the values you would use at say 68 F, and it will adjust to the acutal temp? That would make life a little easier if that is how it works.

    Thanks,
    Mike
     
  10. Jorge

    Jorge Inactive

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    It has a probe you put in the developer or water jacket and the timer speeds up or slows down depending at which temp it was calibrated. Zone VI or Calumet sends them calibrated at 68 ºF, but I modified mine to read as "normal" time at 74 ºF.
     
  11. photomc

    photomc Member

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    Thanks Jorge...this technology stuff is great! Ok, so I'm a few years off the mark....
     
  12. Jorge

    Jorge Inactive

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    If you are interested in one, I think those from RH designs are better. A bit more expensive but better made IMO.
     
  13. lee

    lee Member

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    you can calibrate for real time at whatever temp you want. I chose 68f and then I took the thing apart and turned it on and adjusted the pot until it was right with real time. Then it is calibrated.

    lee\c
     
  14. Jorge

    Jorge Inactive

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    Yeah, that is what I did too......