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  1. #1
    Photo Engineer's Avatar
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    Divided developers

    Seeing posts on APUG regarding divided developers for B&W and even for color, I feel moved to make one very important point for you who favor this method.

    A divided developer works by imbibing, or soaking up, part A and then carrying it over into part B where development takes place. It relies on imbibing the right amount of developer, and then it relies on exhausing it either by use or diffusion in the two step operation.

    Now, here are the problems.

    Divided developers are dependant on swell and thickness of the film. If either or both of these vary, then the results will vary regardless of the ability of the film emulsion itself to respond.

    If a manufacturer makes a film "X" and then improves its sharpness by coating less gelatin, then the emulsion is thinner and swells less. Regardless of the fact that may be the same emulsion, it will respond to a regular developer as desired, but will respond to a divided developer in a different, and less effective manner.

    If a manufacturer were to change from formaldehyde hardening to glutaraldehyde hardening, the coating would be as hard, but would swell slightly more in the latter case, giving more reactivity to a divided developer, but the normal reactivity to a normal developer.

    Therefore, you should very carefully examine each film for your divided developer before going ahead with a given project, or you may not get what you expect. Coating formulas change all the time.

    If Kodak or Ilford were to change the speed of the coating machine, for example, they would re-formulate the film to give identical results in a given developer. They cannot test all possible developers, so they have a standard release test. If the film works, it is sold, but this change, whatever it was, would impact more heavily on the divided developer.

    I suspect that is why modern films seem to work less well in divided developers. Among other things, they are much harder than older films by virtue of using a different hardener than the old formalin hardener. They are thinner, because t-grains are only 'two dimensional' rather than 3 dimensional 'rocks' or klunkers as we called them. Therefore, less gelatin has to be coated. The 3 D grains would stick up out of the gelatin if there was not enough gelatin to cover them. (that is a simplistic picture but you get the idea).

    PE

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    Not only do I get the picture I am better for being given the opportunity to have seen it. Thank you.
    Claire (Ms Anne Thrope is in the darkroom)

  3. #3
    kwmullet's Avatar
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    PE,

    Very informative and helpful post. Thanks very much!

    I've advocated a divided developer (Diafine) for newbies when first trying to get them started because of ease of use. It's good to know that routine testing and retesting is called for when using it (at least until graduating to something like Pyrocat, that is).

    Once I get my darkroom back up, though, I'd been planning on using a divided Ansco 130 as referenced in this thread and this one as a paper developer. Assuming that paper emulsions are much thicker than film, is it safe to assume that paper is more likely to perform consistenly over time with divided developers than than is film?

    -KwM-

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    Photo Engineer's Avatar
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    KwM.

    NO!

    Paper formulas can vary in gelatin levels just as films can, but the limits of variation are lower than film. Even so, you would probably see it with a divided developer.

    PE

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    kwmullet's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    KwM.

    NO!

    Paper formulas can vary in gelatin levels just as films can, but the limits of variation are lower than film. Even so, you would probably see it with a divided developer.

    PE
    ...so the only way to compensate would be to adjust the formula for part A of Ansco 130 to make it more or less strong, right? Any guidance about how to approach that, should one find it necessary? Or am I getting away from a possible subtext of your message which might be "divided developers -- not such a good idea with contemporary materials"?


    -KwM-

  6. #6
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    Divided developers are just fine AFAIK.

    I personally avoid them due to the potential for problem as noted above.

    I think that with appropriate testing, they are just fine for a given product. For example, with a 100 sheet box of 8x10, you could use 2 sheets cut into 4x5 and have 8 test sheets for the developer. Once the base line is established, the rest of that box, and every box with the same emulsion # should perform exactly the same.

    I see no real problem then if that is what you prefer.

    With all that I have to do in my DR, I have little time for this type of additional problem, you see. So, it is not that they are bad developers.

    PE

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    I think that there is provided here, not said but extractible from it, the idea to, if you consider divided devlopment very important to you to buy large, relative to your useage, of those films that you use this method on and to make sure they are kept frozen and are of the same emulsion batch. When changing to a new batch test at least one sheet.

    Hey, life already has more uncertanties than I prefer.
    Claire (Ms Anne Thrope is in the darkroom)

  8. #8
    Maine-iac's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    KwM.

    NO!

    Paper formulas can vary in gelatin levels just as films can, but the limits of variation are lower than film. Even so, you would probably see it with a divided developer.

    PE
    I agree about the film, but not about paper. I never met a divided paper developer I didn't like. Have used my old standby variant of divided Ansco 125 for years with a wide variety of papers, ancient and modern, graded and VC, and have never noticed any difference in the results that I could attribute to the developer.

    With graded papers, I frequently ran two Bath A trays--one with Ansco 120 (essentially Selectol Soft) and one with Ansco 125-- (minus the carbonate, of course) and was able to easily get intermediate grades by choosing one or the other for the first bath. Especially in darkrooms with hard-to-maintain temperatures, divided developers can be lifesavers. As you say, film is a bit more tricky, but in my experience, paper is a breeze.

    Larry

  9. #9
    Photo Engineer's Avatar
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    Quote Originally Posted by Maine-iac View Post
    I agree about the film, but not about paper. I never met a divided paper developer I didn't like. Have used my old standby variant of divided Ansco 125 for years with a wide variety of papers, ancient and modern, graded and VC, and have never noticed any difference in the results that I could attribute to the developer.

    With graded papers, I frequently ran two Bath A trays--one with Ansco 120 (essentially Selectol Soft) and one with Ansco 125-- (minus the carbonate, of course) and was able to easily get intermediate grades by choosing one or the other for the first bath. Especially in darkrooms with hard-to-maintain temperatures, divided developers can be lifesavers. As you say, film is a bit more tricky, but in my experience, paper is a breeze.

    Larry
    Larry, just to use an example for you, many paper types contain incorporated developing agents and many do not. Their response to divided developers will differ sharply! This is because the incorporated agent diffuses out in the first bath and the paper is designed to work with it present.

    Another example might be an RC and a baryta paper, or two baryta papers from two manufacturers with no incorporated developer. Depending on silver and gelatin levels, these 4 products could react vastly differently to divided developers, but react the same to something like Dektol.

    But, as I always say... "Use what works for you".

    PE

  10. #10
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    I have to agree with Larry on Divided Developers, a description that seems to be the fashionable way of referring to Two Bath Developers. For 25 years I have used all manner of two bath developers in in conjunction with numerous papers in my print making and have never been disappointed with the results. I think we are in danger of getting bogged down in technical and manufacturing speak when, in my opinion, we should be making prints, developing films and making judgements with the eyes and heart. Certainly I am not critical of people like Ron imparting knowledge and years of experience in the manufacturing side of photographic products, but the final judgement should come from the sensitivities of the photographer and not from techno speak. Consequently, if it works for you my advice is to disregard the techno speak.
    "Digital circuits are made from analogue parts"
    Fourtune Cookie-Brooklyn May 2006

    Website: www.lesmcleanphotography.com

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