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  1. #11
    Mustafa Umut Sarac's Avatar
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    So we need to create the colors of ilfochrome and we need to mix silver halide plus dye and plus catalyst and finally the color is ready.
    It would be a very strong againts all conditions. Do this final color chemical soluble in water or alcohol ?

    What is that catalyst ?

    Thank you AgX.

    Umut

  2. #12
    AgX
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    It would be proprietory. Though there have been postings here about synthezing a apt catalyst.

  3. #13
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    I found Rudefous post at articles , here it is .

    The MSDS and many other descriptions I found online claim that 2,3,6-trimethyl-quinoxaline are used by Ilford. This substance, however, seems to be difficult to get, at least Sigma Aldrich doesn't seem to carry it. The Ciba patent mentions that very good results are obtained if a mix of two catalysts are used which have different redox potential, and based on that patent a combo of 2,3-dimethyl-quinoxaline and 2-hydroxy-3,6,7-trimethylquinoxaline could be very promising. I have, unfortunately not delved into this deeply enough, but the Ciba patent does mention patents which could provide useful recipes.
    Last edited by Mustafa Umut Sarac; 06-07-2013 at 04:48 PM. Click to view previous post history.

  4. #14
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    What else needed ?

  5. #15
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    You need 3 coatable emulsions sensitive to R/G/B light. You need 3 Azo dyes such as Solantine Yellow, Solantine Pink and Chicago Blue. You need a developer such as Dektol, an acid dye bleach which is basically Sulfuric Acid mixed with a catalyst. One such is Phenazine. You need a fix that is a B&W fix.

    There you go. Simple as can be. I've hand coated this mix and made some quite nice demonstrations of dye bleach.

    But that was at EK. At home here, I did a single color Magenta, and posted the results elsewhere.

    PE

  6. #16
    Mustafa Umut Sarac's Avatar
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    Thank you , I remember now , I saw the red picture and it was an elegant color and strong , I dont know how to describe it technically .

  7. #17
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    Good hue and saturation!

    PE

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    J.S. Friedman dedicates a whole chapter of "History of Color Photography" to Dr. Gaspar and his dye destruction process. The book is in English and is available for free online at http://archive.org/stream/historyofc...ge/n5/mode/2up and it is a wonderful source for information on many color photographic processes.

    Dr. Bela Gaspar was one of the group of brilliant Hungarians who began remarkable careers in Hungary before WWII and then had to flee because of Nazi persecution. Gaspar himself wound up living in Beverly Hills, California and eventually his patents were licensed to several color film companies. He donated his papers to UCLA. Some of these patents were used to develop Cibachrome and Ilfochrome, which were both color processes depending on the destruction of dyes or dye precursors.

    Gasparcolor was developed during the 1930's and some said that it produced better color than Technicolor. It had several advantages, but principally it allowed a laboratory which had only developed black and white films to develop full color films using ordinary black and white equipment and chemicals. This was unlike other color film processes and several Gasparcolor films were produced. Some of these movies are available on Youtube.

    All of the color dyes were already incorporated in the Gasparcolor raw stock and the lab merely bleached out the color where it was not wanted. However the raw stock had to be exposed three times, one for each primary--red, green, blue--and Technicolor would not license their camera to Gaspar, so he did not have access to separation negs. An ingenious modification of a European movie camera was built which could produce alternating frames which recorded the scene in red, green and blue light successively; by filming at 72 frames per second and step-printing the three frames to a single full-color composite frame the camera could produce a full color movie that looked normal except for some fringing. I don't know of any examples of Gasparcolor films produced by this camera but I have seen a documentary of the current owners who showed the camera--it still exists--and described the rotating tri-color filter wheel in front of the lens.

    Gasparcolor used commercially available dyes so the dye chemistry was reliable and stable. Without separation negs most examples of Gasparcolor films on Youtube are abstract films or animation, however there is one example of a Gasparcolor print of a Kodachrome(?) movie of a trip down the Thames River in London which has very good color tones. Dr. Gaspar licensed his process to a maker of stop-motion animated cartoons called "Puppetoons". Each frame had to be exposed three times, once through a red filter, once through a green filter and once through a blue filter. Moreover, the red exposure had to be for something like thirty seconds, the green for five and blue for one, (I'm guessing at the numbers).

    I talked to a person who works for UCLA Film and Television Archives. He said that the Special Collections division of the UCLA libraries is difficult to work with, so it will be a problem to gain access to Dr. Gaspar's papers in their collection. If I do I will make a report to anyone who is interested online. I think Dr. Gaspar was a great chemist and he made an important contribution to color photography.

  9. #19
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    While Gaspar may have used 3 exposures, it was not necessary to do so. The 3 exposures with different times were used to balance the film to the light.

    And, one thing that is missed is that since the dyes are in the film from the start, the film is totally black and thus is very very slow, even with coarse grained emulsions.

    Thus, from the very start, DB materials were slow, sharp but very very grainy.

    PE

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