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Thread: CD-4

  1. #11
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    Nick, I have never heard of HAS (hydroxyl amine sulfate) going boom.

    As for the patents, they must contain a working example of the formula, but it does not have to be the preferred formula. It must be within the spec though. And you can patent a formula or a process.

    So, a patent may say that they use 1 - 5 g/l of NaBr or alkali metal such as this, or mixtures, and they may end up using 2.74 g/l of LiBr and 0.10 g/l of KI in the actual formula. That is a wild example, but you get the idea.

    The same problem crops up in these published formulas. They are not exactly right and I have no idea what they do to your film or paper. I have seen variations that I did in halide content that caused huge swings in interimage or sharpness with the picture looking superficially correct.

    I know that using CD4 with color paper can look right but lead to very bad dye stability and this is published.

    PE

  2. #12

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    http://ptcl.chem.ox.ac.uk/MSDS/HY/hy...e_sulfate.html

    Explosion hazard. The part that worried me was "May decompose explosively in the presence of alkalies."

    Of course the MSDS for water is scary to-)

  3. #13

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    I have formulas for making C41 developer and bleach from Phototechniques Magizine. I am more interested in compounding RA 4 developer which will take some R&D. I was mostly trying to find the most economical supp;ier.

  4. #14

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    The link I posted includes full RA-4 formulas. Uses CD-3. I've also got a second set out of BJP I could scan.

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    Nick, Claire, what can I say but that the developer formulas are not correct for a number of reasons. If you get good results, then more power to you. Knowing what the formulas lack, and the potential for bad results, I will not use them myself.

    The old Darkroom Techniques magazine, precursor to Phototechniques if I remember that correctly published not only formulas but sensitometric curves from several different C41 developers. Those curves showed the variations that you might expect from the different published formulas. Given that, then the color reproduction and image structure also varied, but no one ever reports on those, and they are what make some of these films truly stand out.

    I wish that test equipment for granularity and sharpness was available to us. Then there would be fewer people looking for the magic bullet out there, or using guesstimated formulas.

    I have personally run several different color developers which work with one film, but fail with another color film and the same goes for papers. A given formula may only work 'right' for one product. This is for 2 reasons. 1, the manufacturer tests all of his products and most competitor products in his developer and tailors the film to meet release specs in that developer and 2, the home experimenter who publishes formulas cannot test all films and cannot run the exhaustive tests that the film manufacturers run. These tests include sensitometry, color reproduction, granularity and sharpness and also may include hardness and development sentitivity (to time, temperature and agitation).

    The only formula published out there that seems satisfactory is the RA blix, but even that can be mixed up incorrectly if the pH falls too low. Below about 6.3, the blix can begin to cause dye stability and hue problems among other things. You see, the final pH of color products is critical to those two factors in most all cases.

    PE

  6. #16

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    So far I've used the Laut formulas with Kodak,Fuji,Agfa and Konica film. Pro,consumer and even cross processed E-6 film. My only complaint is the cross processed is too neutral. But that may be something I'm doing. Others have used the formulas for I guess 7+ years. Considering how few films have managed to last that long I figure they've tried more then one film with the formula.

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