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  1. #11

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    Kirk,
    I forgot to say, you never want to be bitten by a mantid! The pain is far worse than any bee sting. And the little twerps do not wanna let go.

  2. #12
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    Howdy gents,

    Ron informed me that there was a thread about trying to find some red sensitizing dyes. Although I've not started messing around with any color sensitizing dyes myself yet, I do come across a lot of information regarding it. Attached is an excellent list of sensitizers from Hans Bjelkhagen's Silver Halide Recording Materials: For Holography and Their Processing. I'd consider this list an authoritative survey of the currently available sensitizing dyes.

    Unfortunately it doesn't say which spectral region they sensitize for, but this information has been hashed out ad nauseum in historic literature. I was recently amazed at how many articles I found in British Journals of Photography, 1900-1918, that discuss red sensitization and the like. Has anyone considered bath sensitization?

    Here's an interesting snippet from Bjelkhagen's book... "The particular sensitizing dyes mentioned above [below] and their combinations were discovered and used by H. Lehmann to produce the best correct-color sensitivity ever achieved in Lippmann photography. However, he kept secret his good formula for Lippmann plates and it was not revealed until after his death. If one wants to try this old photographic technique today, these dyes are definitely the first choice."

    Those dyes are:
    Pinacyanol ----- 1:1000 [chloride, I presume]
    Orthochrom T -- 1:1000
    Acridine orange - 1:500


    I think this would be an excellent trio to work with as an amateur emulsion maker.

    Best wishes y'all!
    Attached Thumbnails Attached Thumbnails Sensitizing Dyes - Bjelkhagen.JPG  
    If you are the big tree, we are the small axe

  3. #13

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    There's a book on IR film from the 1950s that has a similar list, by Clark, I think. It has a good discussion on the history of sensitizing dyes,with a slant towards the cyanine dyes and IR.
    Kirk

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

  4. #14

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    Hi all,
    I have the Bjelkhagen book and have tried to obtain some of the dyes with a lot of frustration. I have seen Bjelkhagen's work with super resolution printed holographs. They are amazing. Images that can be printed in a book, but 3D, high color saturation , resolution and contrast. Dare I use the word 'magical'?
    I would recommend this book to anyone interested in holography. Dye sensitization is only one early chapter.

  5. #15

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    Hello!

    Is it possible to substitute ethyl violet to Methyl violet?
    Thank you for your help.

    Regards,
    Vesa

  6. #16

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    There are recipes for methyl violet, (aka crystal violet), as a red sensitizer, cf. p. 255, Wall, "History of Three Color Photography," available online at:

    http://archive.org/details/historyofthreeco00ejwa

    Reading all of chapter VII is very informative about sensitizing emulsions. Methyl Violet has an absorbance spectrum very close to ethyl violet and chemically the two dyes only vary by substituting methyl groups for ethyl groups.

  7. #17

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    Quote Originally Posted by wildbillbugman View Post
    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,
    What in the heck kind of ANYTHING on this earth could cost $16,800 an ounce? That doesn't make sense. What good could it have possibly have been even to a company like Kodak was in film manufacture at a crazy price like that. Surely there is another reasonable alternative to making film panchro.

  8. #18
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    Quote Originally Posted by Tom1956 View Post
    What in the heck kind of ANYTHING on this earth could cost $16,800 an ounce? That doesn't make sense. What good could it have possibly have been even to a company like Kodak was in film manufacture at a crazy price like that. Surely there is another reasonable alternative to making film panchro.
    $16,800 an ounce would be cheap if a single ounce is/was enough to sensitize an entire run of a particular film.

    Probably work out to much less than a penny a roll.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  9. #19

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    Quote Originally Posted by falotico View Post
    There are recipes for methyl violet, (aka crystal violet), as a red sensitizer, cf. p. 255, Wall, "History of Three Color Photography," available online at:

    http://archive.org/details/historyofthreeco00ejwa

    Reading all of chapter VII is very informative about sensitizing emulsions. Methyl Violet has an absorbance spectrum very close to ethyl violet and chemically the two dyes only vary by substituting methyl groups for ethyl groups.


    Thank you very much for your kind help Falotico. I will try Methyl violet with suggested 50% alcohol. Now how to mix 1:20 000 is an another feat... :0)

    -Vesa

  10. #20

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    There are some drug stores which sell an alcoholic solution of crystal violet (aka methyl violet) using the name "Gentian Violet." These come in small bottles, about one half ounce, and are sometimes mixed with 10 percent alcohol. They are already measured into a concentration of one percent or two percent, that is 1 to 100 or 2 to 100. A half ml of the one percent solution in a liter of water/alcohol would reach a concentration of about 1:20,000. Simply observing the shade of that concentration would give you a reasonably accurate idea of what 1:20,000 looks like and you could try to match it using an eye dropper. The risk in these dyes is using too much. Interested to see how it works out--good luck!

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