Amount of chemistry needed?

Discussion in 'B&W: Film, Paper, Chemistry' started by stradibarrius, Feb 4, 2009.

  1. stradibarrius

    stradibarrius Member

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    I have a plastic 2 reel tank. On the bottom it say for one 35mm rolls 325cc/11oz. are needed and for 2 rolls 570cc/20oz. are needed.
    I am doing test runs with water blah blah blah and noticed that this amount of chemistry just barely reached to the top edge of the reel.

    My question is do the reels need to be completely covered with chemistry?
    When you are processing only one reel do you put the second blank reel in the tank?
     
  2. Ian Grant

    Ian Grant Subscriber

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    It's best to round up and cover the spirals, so for the 570ml/2 spirals use 600ml.

    Usually just use one reel on its own, there's no need to use the second empty. Some tanks have a collar to stop the reel sliding up the column.

    Ian
     
  3. bobwysiwyg

    bobwysiwyg Subscriber

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    Just don't overfill to the point where there is no air pocket at all above the reel(s). You need some for proper agitation during inversions, etc.
     
  4. trexx

    trexx Member

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    Plastic tanks have a funnel. You could not over fill, as when the cap is on there is air space in the mouth of the funnel. I also recommend placing the second empty reel when doing only one real. By doing so you are sure the first real is at the bottom of the tank.

    TR
     
  5. Bob F.

    Bob F. Member

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    I would be happy rounding up to 400cc and 600cc respectively to give extra comfort - just covering is fine if you are placing the tank on a level surface between agitations, but if it's not close to horizontal you may have issues with some of the film not being covered ('tho I expect it would have to be very off-horizontal to do that). If you do not have a collar to stop the single tank moving up the column during agitation, put an empty reel on top as a precaution.

    Have fun!
     
  6. MattKing

    MattKing Subscriber

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    I'm assuming that your reels don't have any film loaded when you do your dry (wet?) runs.

    Don't forget that when the reels have film in them, the film displaces some of the liquid, so the level will be a bit higher in the tank.

    Matt
     
  7. Ian Grant

    Ian Grant Subscriber

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    Of course the other reason for rounding up is it makes calculating dilutions far easier, and this is why I've done it since the late 60's with my Paterson tanks.

    Ian
     
  8. OP
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    stradibarrius

    stradibarrius Member

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    Matt I think you are right but Ian's point about mixing dilutions makes sense.
     
  9. analogsnob

    analogsnob Member

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    If you do inversion agitation fill the tank as if it were at capacity (2 rolls in a 2 roll tank) otherwise the agitation will not be consistant when running different numbers of rolls. Even if the real does not slip around violently the chemistry will and to a much greater extent when half full.

    You also run the risk of foaming and oxidation inverting a less than full tank.
     
  10. Martin Aislabie

    Martin Aislabie Subscriber

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    My question is do the reels need to be completely covered with chemistry?

    Yes completely covered - with a bit more for just in case.

    Ians’ suggestion is a very good one - add more to give you nice round numbers - makes the maths easier - however you do need to retain some "slosh" room in the tank - it allows the chemistry some room to turbulate and mix the stale developer from the film surface with new fresh developer.

    When you are processing only one reel do you put the second blank reel in the tank?

    Yes - When using only 1 film I load up my tank in exactly the same was as I would if there were two films, not forgetting the retaining collar (if your tank has one) - the 2nd reel and retaining collar keeps the roll of film in the bottom of the tank at all times - and hence in the developer.
    If you are doing just one film in your tank - do the same test of finding out how much liquid it takes to safely cover only one roll of film and then applying the above rule - round it up to a nice easy number to simplify the maths.

    You are in theory wasting a little developer needlessly - but the little extra is good insurance against the inevitable mistakes we all make.

    Have fun

    Martin
     
  11. bobwysiwyg

    bobwysiwyg Subscriber

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    Sorry, but I have to respectfully disagree, at least with Paterson tanks. You can overfill to the extent that the funnel is completely full of chemistry leaving very little, if any room for air and agitation. Using either 10 oz. for single reel tank, or 20 oz. for two reel tanks brings the chemistry just to the bottom of the funnel throat.
     
  12. Steve Smith

    Steve Smith Member

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    That's what I do too. It also makes the maths easier so you can work out how much water and how much developer in your head without having to resort to a pencil and paper or one of Mr Babbage's calculating engines.


    Steve.
     
  13. Mahler_one

    Mahler_one Member

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    With Jobo expert tanks, I use:

    In 3010, up to 4 sheets of 4x5, 25cc DDX and 225 cc of Distilled H2O.

    In 3005, 1 sheet of 8x10, 40cc DDX and 360 cc Distilled H2O...2 sheets of 8x10, 50cc DDX and 450 cc Distilled H2O.

    One roll of 35mm/36mm and one roll of 120-use the same volumes as 4x5 above ( need the minimum the tank calls for ).

    Not yet a problem with even development. Of course, fixer is mixed so as to yield the same volumes.

    I tend to be conservative in the volumes so as not to unduly tax the motor of the CPP.

    Hope the information is useful.

    Ed
     
  14. dancqu

    dancqu Member

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    I like to draw a distinction twixt the volume
    of solution and the volume of chemistry. The
    two together determine the dilution; eg, 5 ml
    of Rodinal and 495 ml of water make a 1:100
    dilution. That is 1 part of 100 parts. Dan
     
  15. snowblind

    snowblind Member

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    I had the same conundrum about a year ago. My tank also listed figures that would barely reach the top of the reels and, confusing me even more, the leaflet with the developer stated different amounts per roll too. So I ended up worrying about the amount of solution as well as the concentration of it and I thought "it just can't be this complicated."

    Finally the penny dropped: once there's enough (i.e., the film is covered), the same surface area of film, over the same amount of time, will come in contact with the same amount of solution. So, I rounded the figures up, keeping the dilution as it should be, and made sure the reels were thoroughly covered. It worked and has done so consistently ever since (not that that's been tested with densitometer readings or anything).

    In fact, with my tank, even when both reels are on the spindle, they move up and down a bit during inversion so, even if the capacity stated on the tank is theoretically enough to cover the film, the reels could (and would) float a little. It occurred to me that I'd need some sloshing space but I found that the light-proof funnel area in the lid gave plenty.