Developer-incorporated emulsions

Discussion in 'Silver Gelatin Based Emulsion Making & Coating' started by joshverd, Jan 29, 2007.

  1. joshverd

    joshverd Member

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    What effect does adding developer to a film emulsion have? I've heard it can increase speed/contrast. Is this correct? Anyone know the chemistry behind it?
     
  2. Photo Engineer

    Photo Engineer Subscriber

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    AFAIK, you are correct. To have it work properly, a blocked developer is used otherwise the emulsion would be fogged by the developer rather rapidly. Most common developers are blocked hydroquinones.

    It increases contrast.

    PE
     
  3. PhotoJim

    PhotoJim Member

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    And increases capacity in your print developer, since you are working it less hard.

    I prefer non-incorporated emulsions, but they do develop more slowly.
     
  4. Photo Engineer

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    So far, the non-incorporated developer emulsions are bromide or high bromide Cl/Br and the incorporated seem to be higher Chloride. This would seem to be counterintuitive to me as the higher chloride emulsions tend to be higher contrast and develop more rapidly. But I am just guessing as to content. I have no way to measure halide currently in an existing coating.

    PE
     
  5. joshverd

    joshverd Member

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    I have heard others speak of their preference for one or the other.

    Are we talking about film or just paper emulsions? Are both available commercially?

    If so, what are some examples of incorporated/ non-incorporated.
     
  6. Photo Engineer

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    At present, only paper emulsions contain chloride, chloro-bromide or pure bromide emulsions. Film emulsions are bromo-iodide. (there may be 1 or 2 exceptions for film which are bromide, as there may be a bromo-iodide paper, but I'm not sure of current products)

    All of these are commercially avaialble.

    IDK which have developer and which do not. I've posted a test that you can run yourself on your own paper. Ilford says that their MG paper is not developer incorporated, but it gives a positive test. Kentmere says that theirs is, but gave a negative test, so the test may be unreliable. I have no chemical means, other than the test, to verify this, and cannot test all papers.

    PE