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  1. #1
    holmburgers's Avatar
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    "Cross-Processing", but not really... alternative processing techniques for E6 & C41

    Something I've wondered about is the ability to create a negative from an E6 film and a positive from a C-41 film.

    However, without using the wrong process to achieve it, which is what the traditional x-process is.

    As I understand it, the 1st developer in E6 is basically a black & white developer with some additional silver solvent in it; basically identical to the 1st developer in black & white reversal processing. Then, there is a bleach & re-exposure and the 2nd color coupling development.

    So, it seems an easy enough thing to just skip the 1st developer, go straight to the 2nd developer, yielding a negative.

    Alternatively, a C-41 film could be processed in a 1st developer that is nothing more than a b&w+AgX solvent dev'r, and then bleached, re-exposed and color coupling developed to yield a positive.

    Although, the positive wouldn't be suitable for direct viewing due to the integral masking, it would be finer grained by virtue of being reversal processed and have better color reproduction from the CC-masking. This might make for a superior scanning medium.... *cough *cough

    So, has anyone done this? How different are the color coupling developers for E6 and C41? If there is no difference, then I guess that basically this is exactly what normal cross-processing is and shame on me for not doing my homework. But assuming they're a bit different and optimized for the particular film, then superior "cross-processed" results might be achieved by this method.
    If you are the big tree, we are the small axe

  2. #2
    Mike Wilde's Avatar
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    The colour couplers in E-6 and C-41 are different. Hnece CD-3 and CD-4 as the normal developing agents. For c-41 the orange mask is used to shift the yellow, cyan and magenta layers to prevent them from crossing one another, and thus allow them to be separately filtered.

    There is a Kodak book called Copying and Duplicating that taught me a lot about this in the process of me working out the speed and filtration needed to use some out of date dupe films.

    Processing E-6 as a reversal will not have this mask present, and even superimposing a c-41 mask will not bring the colours into line to prevent crossed curves. Early colour neg films without masking (agfa I think) had this challenge. The mask also corrects for imperfect dye denities ie some of the red sensitive layer interacting with blue etc.

    The density of the different colour curves in C-41 must be matched to the sensitivity of the different colur layers of the paper in process RA-4.

    The density of the e-6 may not be offset; in fact I don't think it is at all, but I'm not up on the uniformity of vision sensitivity of human's optical channel relative to different light frequencies.

    Hope this gives you some thoughts to futher chew on.
    my real name, imagine that.

  3. #3
    holmburgers's Avatar
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    Thanks Mike,

    You're right that E6 dev'd as a neg will have no masking. The mask in C41 is a function of the coupler's themselves being coloured reddish and yellow for the magenta & cyan layers. These offset the fact that these mag/cyan dyes are not "theoretically" ideal in their transmissions. Since the goal is a neg that's suitable for printing, it's appearance is of no importance, unlike a slide.

    So E6 as a negative would be more or less just interesting.. probably of little value.

    C41 as a positive though, could be great for the above stated reasons, and useful for making direct separation negatives onto panchro film. Or for making negative prints on RA-4... if you're into that sorta thing

    It's mainly just a thought experiment I guess.
    If you are the big tree, we are the small axe

  4. #4
    Photo Engineer's Avatar
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    Chris;

    There is NO bleach before the E6 color developer. That is a BIG mistake.

    Second, the E6 color developer, intended to go to completion, is a fogging developer and cant work properly as a straight negative color developer. That is your second mistaken assumption.

    PE

  5. #5
    Athiril's Avatar
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    I've xpro'ed Reala using a first dev I made myself, and rest were E-6 steps, results were excellent. I would say many of them could even be projected, many of my C-41 positive xpro's appear colour balanced with a ~6500K backlight as opposed to 3200K. Ascorbic acid fiddles with the mask somehow - even after processing, I watched the mask change in colour before my eyes in an ascorbic acid solution.

    I've cross-processed Astia to a colour negative, using diafine as a first developer, then fix, bleach, colour developer, bleach, fix, stabiliser, with wash steps. The colour is exceptionally strong, I have one that has such strong colour on a portrait, that I can't completely colour balance it digitally, it is ridiculous.
    Last edited by Athiril; 04-26-2011 at 05:09 AM. Click to view previous post history.

  6. #6
    holmburgers's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    There is NO bleach before the E6 color developer. That is a BIG mistake.

    Second, the E6 color developer, intended to go to completion, is a fogging developer and cant work properly as a straight negative color developer. That is your second mistaken assumption.
    Forgive my ignorance of color processing steps! I'm looking at the big picture, and missing the details.

    So, I guess the color coupling fogging developer only works because the negative image is undevelopable at this point, ergo, basically it would fog the whole thing if there was no silver neg image. That certainly doesn't sound useful...

    Ok, well how about C-41 making a masked positive. This is probably the more intriguing route. What would a b&w reversal-type 1st dev do to a C-41 emulsion? Would it harm the couplers, the masking dyes, etc.? I guess the "bleaching" sequence would be tricky... how to remove the negative silver image? Hmm... I'm thinking myself into a corner...

    Now Athiril, I'm curious about your process for X-pro'ing Astia. Why did you have to have a 1st dev? I thought the color developer took care of both silver and dye.

    As is probably evident, I've never processed color and until now haven't tried to understand the processing sequences. However, a lightbulb was lit and I had to propose the idea.
    If you are the big tree, we are the small axe

  7. #7
    Photo Engineer's Avatar
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    Well, Kodak actually made a masked color reversal film for duplicating purposes. It was not on the market very long due to low demand IIRC. C41 developed in E6 yields a low contrast positive image with an orange mask. Treatment in strong acid messes with the dyes and can remove parts of the orange color, but will also affect the other dyes as well also IIRC.

    PE

  8. #8
    holmburgers's Avatar
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    PE,

    I'm just going off the wikipedia entry for E-6, but I don't understand why the color developer in E6 is fogging if the reversal-bath/light-exposure achieves this. Nor do I understand how the existing negative image doesn't become more developed at this stage.

    As for removing the silver image in E6, it appears that this is achieved in a fundamentally different way than in b&w r.p. (a strong acid & dichromate), which would presumably harm the dyes..?

    Furthermore, why does E6 call for a pre-bleach and a bleach, followed by fixing. C-41 only requires a bleach and fix, and that takes care of both types of silver (halide/metallic), so I'm confused.. basically.

    These color systems are marvels of complexity!

    There's got to be a better way to cross-process film, by taking select steps from each process and combining them to make a unique process that is more suitable and less brute force.
    If you are the big tree, we are the small axe

  9. #9
    Photo Engineer's Avatar
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    Chris;

    It would take pages to go into the theory behind these two processes, but here is the gist of things. NO developer develops all of the Silver regardless of time and temperature, unless drastic formulation changes are undertaken to do this. When you do, the developer will then fog the emulsion, and so these developers are generally reserved for color reversal. Second, the first developer must develop all of the silver as well, and therefore it is foggy by comparison to regular B&W developers. If the first developer does not develop all of the silver, the color developer will and thus you will have a high dye dmin.

    So, strong first developer to leave no Silver Halide in what will become the whites of the slide. Strong color developer to insure that every bit of Silver is developed.

    Since all Silver is developed and no Silver remains, the dye clouds are surrounded by 100% Silver metal which puts a load on the bleach by having to act on a lot of Silver, and also because the Silver may be surrounded by dye. So, the bleach is designed to act accordingly. Using Dichromate affects hardness, image quality and dye hue and stability. Dichromate bleaches are actually "Blixes" in the sense that they both bleach Silver and remove it at the same time. But, they are not good for color.

    A reversal color developer has about 2x the ingredients of a B&W or negative color developer.

    How is this?

    PE

  10. #10

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    Hi Holmburgers,

    How about trying Rollei CN 200 Digibase film? It's an unmasked C-41 film, so you could cross-process it without having the orange mask to deal with. I've never tried it myself, but there's a thread about it here. It might give you the results you are looking for.

    Cheers,
    kevs.
    testing...

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