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  1. #1
    glbeas's Avatar
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    Difference between RA4 formula and C41 formula

    Just out of curiosity I was wondering what the functional difference between C41 and RA4 chemistry is, besides the obvious fact one is for film and one is for prints. I have a very old box of Ektacolor paper and no RA4 but do have some c41 mixed from a Flexicolor kit and was thinking of playing around with it and seeing how bad it looked. The paper is too old to be worth buying an RA4 kit just to play.
    Gary Beasley

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    The C41 developer uses CD-4 color developer and contains 'buffer' halides suited to films. The RA chemistry has buffer halides suitable for papers and uses CD-3.

    The RA chemistry uses a fairly weak blix, the C-41 uses a very strong bleach and fix. The C-41 uses a stabilzer.

    PE

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    glbeas's Avatar
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    So would CD-4 develop an image on the Ektacolor? I assume I could just dilute the bleach and fix and ignore the stabilizer. What are the buffers for each in general? Would the C41 buffer inhibit the development of the print paper to any degree if I were to add some of the proper buffer?
    Gary Beasley

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    CD-4 will produce dyes with inferior hue and dye stability with color paper. The paper will develop poorly due to the halide content of the C41 developer. The reverse is also true. The buffers are NaBr, KI and NaCl. They are not interchangable between films and papers.

    RA bleach fix cannot be used with film, but film bleach and fix can be used with paper with proper dilution.

    But, you are on your own.

    PE

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    glbeas's Avatar
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    Thanks. My main thrust on trying this is getting practice with using the equipment. My darkroom is color capable but to date I've never done more than soup c41 and E6 film. It will be interesting to find out how I need to set up the workflow and how well I can handle the color analyzer, even if it is with inferior materials. When I do get to buy some decent print paper and chemicals at least I will know where some of the problem areas will be.
    Gary Beasley

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    RA-4 color print chemistry is probably the most inexpensive of the color chemistries..partly because you only need 2 things...developer and blix, and also the easiest to use. I have found the concentrates (before mixing into working solution) last a very long time. Since everything is liquid concentrates you can sub-divide the chemistry and only make a small amount of working solutions if you wish, and store the bulk of your chemistry in the concentrate form.

  7. #7
    glbeas's Avatar
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    Thats good to know. My printing sessions will probably be infrequent due to lack of time. After I do the shakedown of my system I may find I like this!
    Gary Beasley

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    Gary. I am not at all sure that C41 will give you a useful trial run for RA4 although it might be an interesting experiment. It's worth setting up an analyser properly and to do so I think you need the proper chemistry but I'd love to see the results of the experiment just out of curiosity.

    pentaxuser

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    Just a heads-up: Given all the variables (different paper, different developer, possibly other differences), you'll need to recalibrate your analyzer when you move on to current paper and conventional RA-4 developer. Your proposed experiment may be worthwhile for figuring out a workflow, though. OTOH, it might actually cost more to use your C-41 chemistry than to buy RA-4 for experimentation. (I don't know this for a fact, though, since I've not looked at the costs.) You might want to compare the costs and, if fresh RA-4 is cheaper than the C-41 you've got on hand, add an RA-4 kit to your next order from your photo supplier.

  10. #10
    glbeas's Avatar
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    Oh, I'm sure I'll need to recalibrate everything, no doubt. I just want something to play with and this chemistry is mixed and bottled already. Figure I need to use it before it spoils. This is a different direction for me and I want to get a feel for the processes.
    Gary Beasley

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