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  1. #1

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    Is it the case that certain ingredients of film developers, e.g. glycin, pyrocatechin, etc. can strengthen film emulsions so that they become more scratch resistant during the fixing and washing process? I have used two developers on Efke PL 100 (well known for its fragility) and have experienced scratches with one but not with the other. Respectively, Pyrocat HD and PF TFX-2.

  2. #2
    Jorge Oliveira's Avatar
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    What I know about it is that the more alkali a dev is, the more the gelatin will soften.
    But I'm not sure if if Pyrocat is more alkali than TFX-2.

    Never heard that glycin would harden emulsion, but borates (borax, metaborate) used in developers will.

    Jorge O

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    Efke, or rather fotoimpex, recommend a hardening fixer.

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    I recently came across a book of Agfa photo chemistry formulas from the thirties - one formula is called a "Chrome Alum Hardening Bath" and it is used in place of a regular stop bath (short stop as Agfa calls it). Its purpose is to give additional hardening to the film, particularly in hot weather or for tropical development.

    It's 30 grams of Potassium Chrome-Alum to one liter of water.

    Is anyone familiar with this, or have an opinion as to whether it may help with the Efke scratches?
    juan

  5. #5

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    Alum is generally considered useful for hardening emulsions. However there are debates about the archival effects.

    The subject comes up occasionally in relation to papermaking and watercolor painting. I don't know the answer to the archival question. I've used alum in homemade sizing for my homemade papers but I haven't had these papers nearly long enough to evaluate the archival effects.
    Three degrees of separation from Kevin Bacon.

  6. #6
    Ole
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    MACO recommend a hardening developer for their copy films, since most of the damage is usually done in the developer...
    -- Ole Tjugen, Luddite Elitist
    Norway

  7. #7
    Jorge Oliveira's Avatar
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    Interesting. Never heard of a hardening developer before.
    Just hardening fixers. Mybe what Francesco is looking for is a hardening fixer.

    Jorge O

  8. #8

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    Not really looking for a hardening fixer because I noticed that the scratches have appeared even before fixing. I did however observe that using TFX-2 with Efke PL100 has so far resulted in 100% scratch-free negs (about 25 sheets so far - touch wood). Is it the metol? Is it the glycin? Has anyone else had the same observation with Efke PL100 being more scratch prone with certain developers? Or is it simply coincidence (luck) that those sheets I used with TFX-2 did not inadvertently get damaged on the way in and out of the holder and on the way in and out of the BTZS tubes?

    What is the ingredients in that so -called hardening developer?
    Francesco

  9. #9

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    I suspect the scratches occur during the manufacturing of the film, not during the processing.

    However I haven't seen any scratches in my Efke R100 (120 rollfilm).
    Three degrees of separation from Kevin Bacon.

  10. #10

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    The answer to the original question is yes, absolutely. Tanning developers that contain either pyrogallol or pyrocatechin will harden the emulsion of films during processing.

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