Homogeneous Powdered Cemistry

Discussion in 'B&W: Film, Paper, Chemistry' started by Martin Aislabie, Sep 25, 2009.

  1. Martin Aislabie

    Martin Aislabie Subscriber

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    We have been informed many, many times on APUG not to try and make up partial batches of powdered chemistry, as the various components can separate during storage.

    So I am curiously wondering, how to Kodak/Ilford/..….. keep their large batches of powdered chemistry homogeneous in the manufacturing and packaging processes?

    Martin
     
  2. Bob-D659

    Bob-D659 Member

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    Special hardware, Kodak mix and package powdered chems in an inert atmosphere.
     
  3. Photo Engineer

    Photo Engineer Subscriber

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    Kodak makes the several encapsulated parts in individual reactors and these individual parts are each dispensed into the bag or packet before sealing it. If three parts are needed, then 3 different types of encapsulated matrials are dispensed into a bag and therefore, at the beginning, the bag is not uniform as Kodak expects that the entire bag is to be used at once. It also keeps the particles separate before they need to be mixed together and limits contact beforehand. This prevents cracking of the capsules because that premix would have to be continually stirred and this mechanical action would / could wear away the protection layers.

    Some chemicals are not encapsulated and some are and this method also serves to isolate them before packing in the bag under inert gas.

    If you refer to comments on APUG about this warning, you must be aware that at least one of them from time-to-time referres back to the Kodak web site where this warning appears quite clearly in a section on dry chemistry.

    PE
     
  4. AgX

    AgX Member

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    PE,

    Are you able to gvive more informations on this encapsulting of photographic chemicals?
     
  5. Photo Engineer

    Photo Engineer Subscriber

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    I've posted as much as I can elsewhere.

    PE
     
  6. Keith Tapscott.

    Keith Tapscott. Member

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    Depending on which developer(s) you are using Martin, it might be worth considering making your own developers from raw components from Silverprint. That way, you can make up as little stock solution as required.
    I often make just 500ml of stock D-76/ID-11 for films and D-72 for B&W papers at a time.
     
  7. AgX

    AgX Member

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  8. Photo Engineer

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  9. Martin Aislabie

    Martin Aislabie Subscriber

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    PE - thanks

    Where would APUG be without you

    Martin
     
  10. Martin Aislabie

    Martin Aislabie Subscriber

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    Keith, your right and I have considered it.

    I bought "The Darkroom Cookbook" with half a mind to try making some for myself; however, I have yet to succumb to that particular sirens call :wink:

    Martin
     
  11. Photo Engineer

    Photo Engineer Subscriber

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    Martin;

    I try to help. I have given only a generic picture of a very complex process, but it gives you the idea of how things are done on huge scales.

    I'm glad it answered your question.

    Thanks for your comment.

    PE