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  1. #1

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    Plea to APUG chemists and photographic engineers

    Can someone invent some kind of thing that will dye or tone or stain negatives yellow or green in proportion to silver density.

    I'm interested in the VC paper effects since the yellow or green Pyro-like stain acts like a graduated/variable low contrast filter. Maybe there's already something out there, but I don't know of anything.

    Please don't respond recommending Pyro. This would be for 35mm negatives and I don't like Pyro developers with small/medium format film.

    Thanks

  2. #2

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    In theory you could develop the film as C-41 film with the addition of a yellow coupler to the developer. For green you would add both a yellow and a blue coupler. This is essentially what was done with Kodachrome where the film itself contained no color couplers. Each of the three layers were developed separately. You could look at the developer formulations for this process to find which couplers and their concentrations. The process names were K-12 and K-14.
    Last edited by Gerald C Koch; 08-11-2011 at 10:21 PM. Click to view previous post history.
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  3. #3
    PhotoJim's Avatar
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    Have you tried all pyro-based developers?

    PMK works well for me on 35mm.

    If you're not happy with 35mm results with pyrogallol or pyrocatechin, perhaps shooting 120 would let you get the results you want. I don't think it likely that a chemist will formulate a way to emulate pyrogallol staining when pyrogallol already does it.
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    PMK is a wonderful developer for sheet film but staining/tanning developers developers are too grainy for me in 35mm and even medium format. I'm not a medium format shooter anyway, just large format and 35mm. Sorry.

  5. #5

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    Quote Originally Posted by Gerald C Koch View Post
    In theory you could develop the film as C-41 film with the addition of a yellow coupler to the developer. For green you would add both a yellow and a blue coupler. This is essentially what was done with Kodachrome where the film itself contained no color couplers. Each of the three layers were developed separately. You could look at the developer formulations for this process to find which couplers and their concentrations. The process names were K-12 and K-14.
    Interesting. I had started to think along these lines but only vaguely given the inadequate depth of my color chemistry knowledge.

  6. #6
    Mike Wilde's Avatar
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    The colour couplers are in C-41 film layers, but not in b&w film, afaik.
    C41 film couplers, when the oxidized development by-product can link to them produce a colour.

    I am not aware of how such a colour would be producted proportionately to the silver density in b&w film.
    my real name, imagine that.

  7. #7
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    It sounds a little like the dye transfer method. Wasn't Technicolor done in a similar fashion? That is, bleach the silver and harden the gelatin, which would then be dyed and used as a printing matrix.

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    Michael, what you want to know about is dye-mordanting techniques. There are ways to do exactly what you want; stain an image in proportion to its silver desnity. You can even bleach out the silver leaving only a dye-image. A stain like malachite green should work admirably, and you can easily get this from a wide array of sources.

    It's different than dye transfer in that you won't be etching the film to make a relief matrix. I don't think this would work with commercially available b&w films. However, erikg is right in that a dichromate-bleach (like carbro) will harden the area surrounding the silver. In this way you could theoretically obtain a planographic matrix, which is not etched, but consists of tanned & untanned gelatin. The trick is, that the stain will go into the untanned areas, so that you be able to get what you're after. A relief matrix contains only tanned gelatin since you've etched/washed away all the untanned.

    This planographic matrix was used to make dye-imbibition prints (dye-transfer) in the old Pinatype Process. The dyes are different though, and you have to use positives instead of negatives. Technicolor used the relief technique, which is akin to Kodak's classic "Dye Transfer" process.

    If that sounds like what you're looking for, let me know and I'll try to dig up some resources.
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  9. #9

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    I don't know I didn't even understand most of what you wrote

  10. #10
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    . . . .


    Focus on the first paragraph. There are methods that allow you to "dye or tone or stain negatives yellow or green in proportion to silver density". This is called dye-mordanting, and it's fairly simple.
    If you are the big tree, we are the small axe

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