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  1. #11

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    PE,
    In view of my recent results with my panchro emulsion, Could people add some ammonium iodide to commercial blue sensitive liqid emulsions , then add a green sensitizer(picking which one would be the trick) and thereby make a red and green sensitive emulsion.
    Bill

  2. #12
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    IDK Bill, but Ammonium Iodide causes more fog (in general) than Potassium Iodide.

    PE

  3. #13

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    Quote Originally Posted by JessicaDittmer View Post
    thanks! I'll check out the link and look for that book!-j
    oh, and i forgot probably one of the best places to hang out would be thelightfarm.com
    tons of info, recipes and good folk

    john
    ask me how ..

  4. #14
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    Adding to my last post, I have checked and Ammonium Iodide is not all that stable. It decomposes into Iodine and various Iodine salts such as Iodates. So, KI is the only Iodide salt I would suggest using.

    PE

  5. #15

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    Thanks PE,
    I started using NH4I back befor I got a handle on Alcohol precipitation as a means by which to wash a PVA based emulsion. I was trying to minimize the content of materials that needed to be washed from the emulsion. So I used NH4Br as well as NH4I. Now that I have come to trust alcohol presipitation I should be able to switch back to KI. What about KBr vs. NH4Br, aside from adjusting for M.W? Bill

  6. #16
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    Bill;

    The only two salts that have low stability in that series (that I could find) are NH4I and NaI. These decompose. All others are reasonably stable.

    PE

  7. #17
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    Color negative papers such as Endura or CA must be shot with a heavy red filtration and assuming an ISO value of around 25 after filtration. The estimated process is: 1st developer (D-19 1:2 or 1:3) 2', stop 30", wash 30", re-expose, CD 2' (RA-RT color developer or equivalent), wash 30", Blix 2', wash 2' or longer and all at 68 deg F (20 deg C).

    PE

  8. #18
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    The silver image in color papers is extremely weak. Do not rely on it for imaging.

    PE

  9. #19

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    This is an older thear that has not been commented awhile. I am trying to make a commercial multicontrast liquid emulsion panchromatic. If i have correcty understood or totally misunderstood, variable contrast emulsion/paper should be somewhat sensitive to green light..?


    Using methyl violet (i currently cannot obtain ethyl variant) There is a slight possibility to extend the sensitivity little bit towards red.

  10. #20
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    VC papers are sensitive to blue and green light. The two emulsions have different contrasts and when the color of the exposing light varies, the exposure to these two emulsions varies giving variable contrast. If you try to use this as a pan emulsion, it will work, but the contrast will vary according to the exposing light.

    It would give an odd image.

    PE

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