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  1. #71
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    Thanks for the answer Ron.

    I wonder if there's something one could add to the pre-wash (that's not detrimental to the process) that would leach out more of the dye.

    Who knows... probably a hare-brained idea. But let's say you find a bunch of old panchromatic film that's way too old to use... might be worth it then.

  2. #72
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    A desensitizer will remove sensitizing dyes from the crystals.

    These include the Pynacryptols or Pinacryptols, as there are spelling differences. Today's PINA numbers for dyes derives from this earliest class.

    It will probably do bad things to speed and contrast. Experiments will have to be done.

    PE

  3. #73

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    Pardon me if this has already been posted. We used several of these for lasers and also absorption targets when we were working on optical spectroscopy for cancer detection. All of these dyes are stable and the concentrations, secondary emissions and extinction coefficients are available. The question that comes to mind is how to efficiently go about trying these as spectral sensitizers in an emulsion. It looks like it could take a long time.

    http://www.exciton.com/wavelength_chart.html

  4. #74
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    Bob;

    Just a quick look but about 25% of them look interesting but the rest are not suitable. The time is not a problem, the cost is. And, I can pretty much identify an emulsion sensitizer by structure which is how I figured out that some might work.

    How to get some samples? Can an ordinary human get some?

    PE

  5. #75

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    I don't know if they would take a credit card order, but we can order any of them for you if you want through Soundwave Research if they won't. Some are very expensive but usually not much of it is needed. Not all of the dyes are of the centrosymmetric type, and I only have experience with a few of them that we used as precise spectral markers for development of ratiometers and spectrometers. Like this one http://new55project.blogspot.com/201...sa-poster.html

    Maybe, just maybe, that company would be interested in an organized exploration of other applications addressable with their product line, if conducted by a qualified scientist. In return for sharing the information, they could supply samples to be used in a planned experiment, something like that. Depends on who asks. If it was the GEH and PE I would think they would be honored, or at least polite.

  6. #76

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    "Some are very expensive."
    Bob,
    Could you define "very expensive"? One of the dyes that I use all the time costs over $600/gm. Are we talking more or less than that? A cheaper red-sensitive dye would be great!
    Bill

  7. #77
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    Bob;

    Even a 100 mg sample with a courtesy fee of $100 or so would be good. I can do a lot of work with 100 mg.

    There are so many dyes though it is hard to pick one. They are not in the best format for review either. There must be a better way to present them such as by chemical class (best) and then spectral response (second best).

    PE

  8. #78

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    I think the way to proceed is to find out who the scientist is at that company and ask him/her about the various dyes. That person would possibly learn something too, and may be intrigued about the use of their product with silver halide sensitized materials for intellectual as well as business reasons.

    There was a detailed spec sheet for each one on their website. We used PBD and got less than a gm of it which was 100 times what we needed. I don't think it does much good to speculate on cost until you select the one(s) you want and know how much coverage it could afford. I would not even approach the cost question when calling, as that alerts them in the wrong way. It could turn out that a substitute dye the photo industry has never used is right there in the catalog, and that could be valuable to Ilford, InovisCoat and others who may also have wondered about it, and not had the time yet to explore the dye laser space fully, though I am very sure they are well aware of it.

    Let's find out about performance first because costs vary through R&D to manufacturing quantities. Let me know if I can help - I would not be as conversant as others like PE on the subject, but our lab could call and make inquiries, if we had a few good candidates picked out.

  9. #79
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    There are a few IR dyes there that look interesting. For those wanting to make IR sensitive materials that is probably the place to go. AFAIK, most of the rest of the dyes are unusable, and the usable ones, I have from my sources already.

    Also, I would not recommend perchlorate salts to anyone for use with AgX emulsions.

    PE

  10. #80

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    We thought $100 a gm was quite expensive when we bought the material for spectroscopy. I get McDonald's $1 coffee and think that Dunkin Donuts coffee is very expensive.

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