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  1. #31
    Photo Engineer's Avatar
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    Guys, X-Ray film is placed in contact with a screen the fluoresces when struck by X-Rays. Nuclear emulsions, sensitive to radiation, contain a substance to enhance their sensitivity to specific radiation. See Mees or Mees and James for this.

    Chlorophyll is used by Mark Osterman at GEH. He uses Ivy, and extracts the dye getting a greenish solution. It does not keep its properties long.

    Chris' list should serve us well, as should his suggestion.

    I have not been able to get any information from my contacts, but some of the chemicals Chris suggests are available commercially.

    There, that should answer most questions.

    PE

  2. #32
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    Pinacyanol has been discussed at great length over the past few years. AFAIK, the variability in aggregation, and a tendency to floculate can make it a bit tricky for controllable and repeatable results within the "home lab".
    - Ian

  3. #33

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    Quote Originally Posted by Photo Engineer View Post
    Guys, X-Ray film is placed in contact with a screen the fluoresces when struck by X-Rays. Nuclear emulsions, sensitive to radiation, contain a substance to enhance their sensitivity to specific radiation. See Mees or Mees and James for this.

    Chlorophyll is used by Mark Osterman at GEH. He uses Ivy, and extracts the dye getting a greenish solution. It does not keep its properties long.

    Chris' list should serve us well, as should his suggestion.

    I have not been able to get any information from my contacts, but some of the chemicals Chris suggests are available commercially.

    There, that should answer most questions.

    PE
    Did it answer MY question too, because if it did, I'm sure I'm not versed enough to notice.

  4. #34
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    IDK. Restate the question!

    PE

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    Post 26 and 28:
    08-22-13 04:47 PM #26
    Tom1956

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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.

  6. #36
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    Quote Originally Posted by Hexavalent View Post
    Pinacyanol has been discussed at great length over the past few years. AFAIK, the variability in aggregation, and a tendency to floculate can make it a bit tricky for controllable and repeatable results within the "home lab".
    I think I see the crux of the problem for this forum. (At least I see it as a problem.) "...has been discussed at great length..." Yes, much discussion of everything under the sun. Much less doing. And, far too many conclusions drawn from the discussions -- with little empirical evidence to back up said conclusions. I'm a retired scientist. I'm not much given by nature or training to act that way. I've got a number of lovely handmade panchromatic film negatives and glass dry plates on my light table.

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

  7. #37
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    Quote Originally Posted by Tom1956 View Post
    Post 26 and 28:
    08-22-13 04:47 PM #26
    Tom1956

    Join DateMay 2013LocationUSShooterLarge FormatPosts626

    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.
    Thanks.

    Yes, it can probably be done but most sensitizing dyes are also desensitizers and so getting the correct amount is difficult. And proving it works is another matter.

    PE

  8. #38
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    Quote Originally Posted by dwross View Post
    I think I see the crux of the problem for this forum. (At least I see it as a problem.) "...has been discussed at great length..." Yes, much discussion of everything under the sun. Much less doing. And, far too many conclusions drawn from the discussions -- with little empirical evidence to back up said conclusions. I'm a retired scientist. I'm not much given by nature or training to act that way. I've got a number of lovely handmade panchromatic film negatives and glass dry plates on my light table.

    d
    Denise, I agree. However, I must ask if you have wedge spectrograms of your pan emulsions showing good red sensitivity? This would be hard scientific evidence that it works. If you don't, I would be happy to expose a few of your plates for you and return them to you for processing, as I have a Spectro Sensitometer. That is the ultimate proof.

    PE

  9. #39
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    Thank you. That's a generous offer. I know how valuable your time is.

    Actually, I disagree with that approach for us at this time and place in the history of our craft. I think it is a fundamental mistake to consider our efforts a de facto competition with standards based on the latest modern materials that come from a Kodak factory. That's the exact rabbit hole the discussions here so often travel down.

    Today, my hat says 'artist'. I believe good art more often comes from good practices more than from dumb luck, but it is still art. An artist makes the materials his or her own according to personal vision. In other words, the "proof" is in the product (i.e. the art), not a number on a machine. Arbitrary, spurious precision may be seductive, but mostly it's an excuse to procrastinate making good art.

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

  10. #40
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    Denise, I was going by your previous post suggesting that we all get more evidence of our conclusions. This test would compare nothing to nothing in the sense that your plates would be for you alone (even I would not see the results!) and thus you would have that concrete evidence of pan sensitization rather than a guesstimate.

    Any time, I am available for helping you just as I spend time with others here either designing processing solutions or making emulsions.

    Ron



 

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