Color process : trichromy, Ducos du Hauron, colored mica sheets

Discussion in 'Color: Film, Paper, and Chemistry' started by pak, Jun 7, 2009.

  1. pak

    pak Member

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    Hello,

    I'm looking for information on a type of color process that seems particularly rare. The object image consists of two sheets of mica (approx. 5 x 6 cm) superimposed on a thin frosted glass. The image is revealed by the juxtaposition of two colored layers (magenta and yellow). It apparently lacks the third layer of cyan to perfect the rendering of color.

    The trichromy process was revealed by Louis Ducos du Hauron in 1869. In his statement he also proposed a solution to use mica (good for its low thickness and transparency) as a picture.

    Today, I would be willing to learn if some collections around the world and especially in France has similar examples of this technique.

    Thank you very much for the help you can provide me.

    PAK
     

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  2. PHOTOTONE

    PHOTOTONE Member

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    I think the use of thin mica was because cellulose acetate, or nitrate film base was not invented yet, and he needed a thin transparent material so the superimposed images would register fairly well together. There have been a number of processes that create separation negatives and positives using 2 or 3 primaries to achieve a relatively complete color record. As early as the process you reference is, I am surprised he could come up with a panchromatic emulsion to shoot the negatives with.
     
  3. Bob Carnie

    Bob Carnie Subscriber

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    Would you be so kind to mention the processes, this is something I am currently very interested in and any reference or process, using RGB or CMY and separation negatives would be of great interest

    thanks

     
  4. pak

    pak Member

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  5. delphine

    delphine Member

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  6. AgX

    AgX Member

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    Vogel found spectral sensitization in 1873, but still it took him untill 1884 to get somewhat panchromatic. 1902 would be the birth of the panchromatic plate.

    However, when you make successive colour seperations speed is not that much an issue and Ducos du Hauron could start into the red in the mid 70's.
     
  7. amuderick

    amuderick Member

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    You could use very fine mica powders which have been coated with TiO2 to different thicknesses and are interference pigments. Try coating a glass plate and doing a 3 color gum arabic print with interference cyan, magenta, and gold micas. View against a black background.

    Sorry, that was random.