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  1. #21

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    Falotico, thank you for the info. I´m having methyl violet in powder form, but i believe i can dilute it some into distilled water with correct 1:20 000 ratio, and mix this into 50 % alcohol solution. I am waiting for a set of glass plates that are being custom cut for appropriate size, should be ready by tomorrow. After this I can start coating them with gelatin / emulsion layer and start experimenting with Red sensitizing.

    The Ice bath probablty was used as to reduce the vaporization of the alcohol. This gets interesting. I will post some results but this will take some time.

    -Vesa

  2. #22

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    I have had some correspondence with eBay member scuddl_lu6725tbtc@members.ebay.co.uk aka Alan Meredith-Jones of magancol Ltd in the uk who supplies many dyes. May be worth a try.

    russ

  3. #23
    Hexavalent's Avatar
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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 k / ounce is not an unreal price for many fine chemicals, e.g. Aflatoxin = a several $100,000 per ounce.

    The 'high prices' quoted by Sand's Corp. etc., are usually for small amount - the wholesale price for large purchasers is likely a small fraction of the the price given to the average Joe.
    - Ian

  4. #24

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    I just googled this about the methyl violet and WW Grainger popped up as a supplier, as per link. This could be interesting to continue reading this thread,
    http://www.grainger.com/Grainger/wwg...130822161322:s

  5. #25

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    Methyl violet will probably sensitize close to the same manner as ethyl violet. From the absorbence spectrum which I have seen published, ethyl violet sensitizes an emulsion to orange/red light rays as long as 6500 nm and methyl violet sensitizes to about 6400 nm. Both dyes improve red sensitizing when combined with a silver nitrate wash. I don't know why Yoshida lowered the temperature of his dye bath with ice, though I suspect that the lower temperature suppressed the index of absorbence of the dye and allowed a longer time in the dye bath which would cause smaller grains to be dyed.

    Autochromes used ethyl violet as a sensitizing dye for orange/red light. If you notice that Autochromes do not record rich reds very well; most of the red tones lean to the pink/magenta. I suspect that this will be even more of a problem with methyl violet.

  6. #26

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    The reason I'm following this thread is a hairbrain idea of wondering if you could simply soak sheets of green X-Ray film in a solution of this violet stuff and raise the sensitivity closer into the red end of the spectrum. If anybody wants to comment on this knucklehead idea, I'll read it gratefully.

  7. #27

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    Wow, X-ray film! My recollection is that X-ray film contains chemicals which will fluoresce when irradiated with x-rays. The x-ray exposure causes fluorescence and the silver halide grains are sensitive to the visible light which is produced in this manner. I hazard a guess that the visible light is green/blue in color, so the x-ray film is probably sensitized to green/blue. Sensitizing dyes tend to be ionically attached to the silver halide grains so they should be removed in order to make room for the red sensitizing dye. You might mix the red dye sensitizing solution with ammonia which might dissolve some of the built-in dyes; it will certainly dissolve the small percentage of silver chloride grains since silver chloride is soluble in ammonia. Also ammonia might soften the gelatin which has probably been hardened--a softer gelatin will encourage the up take of the red sensitizing dye. Hydrogen peroxide will also soften hardened gelatin. All this is fairly convenient chemistry.

  8. #28

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    Well I figured it couldn't be that easy. It PE even saw read that hairbrained post of mine, he's probably rolling his eyes and possibly rolling on the floor laughing. I'll exit the thread and let all it to return to the better minds like the OP had sought.

  9. #29
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    Did anyone see and note holmburger's suggestion? Post #12. It was very sound. Pinacyanol chloride, together with erythrosin b, makes a perfect (and I mean that pretty much literally) panchromatic emulsion.

    d
    www.thelightfarm.com
    Dedicated to Handmade Silver Gelatin Paper, Film, and Dry Plates.

  10. #30
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    My recollection is that X-ray film contains chemicals which will fluoresce when irradiated with x-rays.
    Not exactly. The film is either just blue sensitive or orthochromatic. When used it is sandwiched in a cassette (flat film holder that opens like a book) between two phosphor coated plastic sheets, called screens, that fluoresce when struck by x-rays. In many ways it is a fairly conventional film although the spectral response is tuned to the spectral emission of the screens for maximum sensitivity. It is also coated on both sides, no anti halation and often on a blue colored base. Whether the dye trick would work or not I do not know but there is nothing really different about the film. Large format photographers use it sometimes because it is cheaper as it is still made in considerable quantity - compared to sheet films.
    All this has happened before, and all this will happen again.



 

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