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  1. #11
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    Domaz is not correct. Sorry Domaz.

    If you go through with the entire C41 process after a B&W process with color film, you will get a blank piece of film. Since development is complete, as is fixation, nothing takes place except for silver removal across the board, in the C41 process.

    I'm afraid that color films in B&W processes are not a good match usually giving low contrast orange red images. You might try other D-19 or D-8 which are high contrast developers, but you are reaching here.

    The color reversal film in a B&W process will give a negative image, but with a yellow cast that is lighter than the red-orange cast of color negative films.

    PE

  2. #12

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    I interpreted Domaz's suggestion as developing in Rodinal without fixing, then doing the regular C-41 process. Since there's no fixing until after the C-41 development and bleaching, I'd imagine this would leave some image, but I don't know how much or how good it would be.

  3. #13
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    Quote Originally Posted by srs5694 View Post
    I interpreted Domaz's suggestion as developing in Rodinal without fixing, then doing the regular C-41 process. Since there's no fixing until after the C-41 development and bleaching, I'd imagine this would leave some image, but I don't know how much or how good it would be.
    Without fixing what's in the emulsion after b&w dev is silver negative image and some unexposed halide positive image. There is not much for a color dev to develop and all that's there would be removed by bleach and fix.

    What makes sense its either fogging the halides to get reversal process or fixing - bleach - reexpose to get what some call acceleration.

  4. #14
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    Quote Originally Posted by srs5694 View Post
    I interpreted Domaz's suggestion as developing in Rodinal without fixing, then doing the regular C-41 process. Since there's no fixing until after the C-41 development and bleaching, I'd imagine this would leave some image, but I don't know how much or how good it would be.
    You would probably get a weak color positive image with this proposal.

    PE

  5. #15

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    A process I learned in school involved underexposing color slide or negative film by one to two stops, processing it in straight Acufine, fixing it, bleaching it, re-exposing it to light, and running either film through C-41 chemistry. The process was called "film acceleration," and it was a blast to play with.

    Films started to change about the time I finished school, and C-41 films no longer worked well. I most enjoyed using higher-speed films like Ektachrome 200, Agfachrome 1000, and the old Scotch 100 chrome and continued to use them for some time. The results were contrasty but printable negatives with enormous, sharp grain. It was a process given to experimentation, which allowed you to control the resulting negatives through exposure and the first development. Finer-grained films work well but tend to be contrastier, and by gosh, Kodak and Fuji both improved their high-speed chrome films to the point where it became tough to produce a lot of grain.

    If anyone is interested, I can post the basic process here, or maybe better yet in the articles section because it would be a pretty long post. It's a lot of fun, especially for analog color printing. I haven't done it for several years because I no longer print color in a darkroom and my scanner isn't good enough to resolve 35mm very well.

    Peter Gomena

  6. #16
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    First of all, what is it that you want to achieve and why?

    Have you considered trying a black and white film in a black and white developer or a C-41 black and white film in C-41 in order to get what you want? What is it that you want?
    Last edited by 2F/2F; 05-19-2009 at 11:14 AM. Click to view previous post history.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  7. #17

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    Yes the film acceleration is what I was thinking of. Here's the link. Looks interesting.

  8. #18
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    The film acceleration is a well known process and requires a rehal bleach. For this reason it is calle in the trade, a rehal or rehalogenation process sequence. You can go through this process a number of times if you omit the final bleach and fix and by this means you can jack the contrast up sky high. However, negative films have a definite limit to dmax as they are what we call "coupler limited" for good sharpness and grain.

    Sequence:

    B&W or color develop
    wash or stop or best, acid clear
    if stop or clear, then wash
    fix
    wash

    Reenter here from point marked below, but first use clear bath and wash.

    rehal bleach (50 g/l Potassium Ferricyanide and 50 g/l Sodium Bromide at pH 5.5)
    wash
    clear (50 g/l Sodium Sulfite)
    wash very well. If you carry over sulfte, color development will suffer.
    Color develop
    wash
    ----------> repeat above after white light exposure to get desired contrast OR....
    bleach
    wash
    fix
    wash
    final rinse

    Do the final 5 steps only if you wish to terminate the process entirely.

    You do not increase speed so much as you increase contrast and therefore the mid range curve that represents the ISO speed value. If the clear is insufficient, you will get high dmin, and if it is not enough or the wash after the clear is insufficient, you will get weak color images.

    PE

  9. #19
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    Astronomers used this technique and called it "Looping".

    You might look up Michael Maunders site in the UK, search for Speedibrews. He made a special C41 colour developer for Astrony but it gives seped & contrast.

    Ian

  10. #20
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    Mr. PE,

    Sounds like a neat technique. Would you mind naming times and temps as well? Is the standard C-41 100F ok for all these steps?

    If a "push" is desired, is this a "superior" method to simply using an extended developer time? If so, how?

    Thanks.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

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