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  1. #11
    Photo Engineer's Avatar
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    Use C41 Starter at the level recommended in the mixing instructions. It differs with each type of kit.

    Edge effects are built into color films and should not be tampered with. Any use of supplementary developers usually messes up the color.

    You can use Cobalt Hexammine Chloride in place of peroxide. It is very hard to get now.

    PE

  2. #12
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    Photo Engineer: I thought H2O2 was able to increase colour separation by increasing the most dense areas of the layers faster than adjacent thin areas? IE; something mildy green would have thinner yellow and cyan dye, so the magenta dye would increase in density more than the same areas on the other layers? Where as rehal re-developing would be more uniform increase?

  3. #13
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    I've seen the H2O2 treatment and rehal processing give similar results, but the H2O2 treatment can differ based on different couplers. I have also seen the H2O2 work well at low levels of Silver.

    But, basically, these two processes are intended to increase dye density proportionally to the Silver present, and all things being equal, they can give equal results.

    PE

  4. #14
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    Ah that is interesting, so H2O2 can help initially accelerate an underexposed image more so than rehal processing?

  5. #15
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    Yes. I have seen catalytic amplification (using the technical term) form complete images from just the latent image. See the patent by V. Bissonette.

    PE

  6. #16

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    how much 3% H2O2 can be added?

    I usually develop at 25 C temperature.


    btw does anybody knows how photographers like Pierre Gonord
    get such colors? http://storage.canalblog.com/24/21/577050/53594178.jpg

  7. #17
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    Quote Originally Posted by Photo Engineer View Post
    Use C41 Starter at the level recommended in the mixing instructions. It differs with each type of kit.

    Edge effects are built into color films and should not be tampered with. Any use of supplementary developers usually messes up the color.

    You can use Cobalt Hexammine Chloride in place of peroxide. It is very hard to get now.

    PE
    Peroxide is easy to get here? In any case I see the patents mention using both a cobalt hexamine complex and hydrogen peroxide as successive treatments. With the cobalt hexamine complex in a b&w dev, and the H2O2 in a follow up colour developer.

    Seems a bit over my head atm to understand it, or why.


    There seems to be something similar (at least to me) in this patent http://www.patentgenius.com/patent/4057427.html

  8. #18
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    At the time of that patent, color paper consumed about 200 mg of Silver per square foot, and the Hunt brothers were driving the price upwards. We came up with a color paper with only about 40 mg of silver per square foot when the Silver price plunged.

    We were also working on a film version but it gave bad grain and sharpness as you can imagine. We worked on several methods to improve this and have corresponding patents.

    PE

  9. #19

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    So it is the best to add some H2O2 in the developer at the beginning of the development?

    Somme negatives have a magenta (the scanned images) cast.
    Somewhere I had read the magenta has to do with the ph of the developer.

    I tried to add some alcohol too, but the result was very dark dense negatives.
    Maybe this destroyed the developer and the film was underdeveloped.

  10. #20
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    I havent fiddled with it much since I do not like wasting both film and C-41 developer.

    You won't be able to keep the developer if you add H2O2.. or other things really.

    Dial your colour balance towards green if your colour is too magenta.


    Did you alter the pH of the developer?

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