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  1. #1

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    Red Sensitive Dye ?

    Hello PE and Everybody else,
    I wonder if anyone out there has had any success sensitizing an emulsion to Red. Sand's SDA3057 works very well to this purpose. But at $600/gram plus a Convenience Fee it is just cost prohibitive. A while back PE wrote of one of his connections possibly producing some dyes for Emulsion Makers. I wonder, is this still possible.
    If I have no alternative, I will buy more of the SDA3057. For my work, nothing but panchromatic emulsions will do. I have been evaluating some dyes. But none do as well as "J Agrigated" SDA3057.
    Believe it or not, chlorophyll, freshly extracted from spinach, shows some red sensitivity, but nothing like SDA3057.
    Just Dreaming,

  2. #2
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    Hi Bill,

    In some very old literature, I have read about "Brilliant Green" and "Malachite Green" giving some red sensitization. I doubt it's what you are after tough. Brilliant Green is cheap, though, and I have a bit coming in to try out. It's used in Russia like Mercurochrome as an antiseptic. You can get it through eBay.

    I have just tried using chlorophyll but with no effect at all. When do you add the chlorophyll and how much? Maybe I did not do it right.

    I've also tried erythrosine for green but added just before coating which did not do much of anything. Next time I will try during precipitation like PE says to do.

    -- Jason
    All this has happened before, and all this will happen again.

  3. #3

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    Dyes used to give sensitivity to red light

    Erythrosine was used by du Hauron in 1878 to produce the first color photographic print using cyan, magenta and yellow. This dye barely sensitized the emulsion to red light--mostly it sensitized it to green. Consequently the exposure through the green filter was for twenty seconds or so, but the exposure through the red filter (actually orange) was for as long as three minutes.

    A discussion of ways to sensitize emulsions can be found in a book which is available for free online, E.J. Wall's "The History of Three Color Photography" (1925), here:

    http://archive.org/details/historyofthreeco00ejwa

    Read his chapter on "Color-sensitive Gelatin Plates". He discusses two good candidates: ethyl violet; and pinacyanol blue. Ethyl violet, IIRC, was the sensitiser used in Autochrome screen plates. It produced passable reds although not as sensitive to deep red colors as more modern emulsions. Ethyl violet is available from Sigma-Aldrich, 25 grams for $39.90.

    The other likely candidate is pinacyanol blue, aka pinacyanol chloride. This is available also from Sigma-Aldrich, a quarter of a gram for $20.20. Besides Wall, see US patent 2047022. There are other dyes, consider cyanine. I understand that Malachite Green tends to fog film, but Wall does mention it in one recipe.

  4. #4
    kb3lms's Avatar
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    There are so many mentioned by the likes of Eder, and probably many more today than were available in his time. The cyanines are the best, as we know, but they are also expensive. Some of these other cheaper dyes are interesting to try, though, as alternatives. But who would have time to try them all!
    All this has happened before, and all this will happen again.

  5. #5

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    Thanks for more response than I dared to hope for! I Think I might already have some of the dyes mentioned. I will be doing some tests soon.
    I requested a new quote for SDA3057. They keep making it more expensive.
    For chlorophyll, I always start with packages of baby spinach leaves from the suoermarket. I have been using 92% Isopropyl alcohol. I add the chlorophyll at 200-ng per mole of AgNO3
    It may be better to add befor preipitation. Also IPA may not be the best solvent
    Bill.
    Bill

  6. #6

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    Bill, we use acetone as a solvent for chlorophyll analysis at work.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  7. #7

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    Hi Kirk,
    I am glad to hear from you! There are at least 6 different "kinds" of chlorophyll, A through F. Different solvents may extract different types, or worse, alter different types. Someone suggested that Heptane would extract Chlorophyll B from a more hodge podged mixture. Yes, "hodge podged" is a recognized Scientific term.
    We are still waiting for you to make a T-grain emulsion.
    Bill

  8. #8

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    We'll need to wait a bitmore for my next emulsion. But my daughter was quite excited by all the little praying manti that hatched from the eggs we bought last week! She wanted to keep several as pets, but I talked her into letting them go into the garden. I secretly named them all "Lenny"....
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  9. #9

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    Kirk,
    You made the right choice by not keeping these mantids. Not all species are suited to be pets. Those species from arid areas are aggressive because they need to be. Those species, like Lenny, from forested areas can just let their meals come to then. These are the gentle mantids who do not mind being handled.

  10. #10

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    Thanks for that info, Bill. I had been thinking about getting one as a pet. I'll do some research in species first though!

    "The Gentle Mantids" - that would be a good name for a band!
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

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