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  1. #31
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    Here are dye bleach catalysts from PS and E journal Vol 18, #5 in an article by Dr. Armin Meyer, Ciba Geigy Photochemie Ltd, Research Division.

    From figure 6, he lists pyrazine, quinoxaline, 2,3 dimethyl-quinoxaline, phenazine and napthazine.

    I can get more from other publications if you wish, but it appears that the notes that I took on the exact formulas have vanished and all I have is sketchy information.

    If Ilfochrome uses a yellow silver filter layer, it can interact with the dyes in adjacent layers during the bleach process and lower their density. A yellow silver layer would have to be inactivated or somehow isolated from the adjacent layers to prevent crosstalk. If it uses a yellow dye layer, then this layer could interact with the silver in the adjacent layers and end up raising their density as it uses up silver being bleached itself. So, any yellow filter layer would have to be inactive or removed before the dye bleach process began. I suspect that the layer, if present, may be somehow compensated for in the design of the product.

    You might do a search on Armin Meyer in the patent literature.

    PE

  2. #32
    Dug
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    SkipA:

    My source for P30 kits is www.rainierphoto.com.

    They are a Seattle supplier with good prices and are super helpful - they ship.

    The photo stores in Seattle appear to be "renovating" their analog photo areas, and you can probably guess that the floor space devoted to them is not increasing. *Sigh*

  3. #33

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    Quote Originally Posted by Donald Qualls
    Given what the process is, I'm not sure I understand the need to remove a masking layer in developing. Won't that layer (presumably a colloidal silver yellow filter layer like the ones found in C-41 and E-6 materials) be removed in the bleaching and fixing steps, just like the developed silver image?
    Hi Donald,

    As PE suggests Ilfochrome has a yellow filter/silver masking layer between the yellow dye (blue sensitive) and magenta dye (green sensitive) layers to help reduce crosstalk. The yellow dye layer is nearest the top, followed by the magenta layer, followed by the cyan dye layer (red sensitive). Ilford made the change many years ago in order to improve the blue (magenta+cyan) reproduction and it needs to be removed before bleaching or you end up with a strong dark blue cast to your image. Testing continues...

    Roger.

  4. #34
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    Okay, so you have a developer with a mild bleach in it -- thiocyanate -- to remove the mask by converting it to a form that doesn't interact with the dye destruction bleach.

    Did the original Ciba folks who developed this process have two heads, by chance?
    Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.

  5. #35

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    Thanks god, I still got quite a few P30 kit.

    I got this from the ilford forum.

    Here's the word from management:
    "The reorganization of Ilford LTD. did cause interruption to production in the factories. Chemical production has been re-established and inventory levels of chemistry and media are returning to normal. We intend to support the Ilfochrome Classic product line for as long as market demand is sufficient to support it."

  6. #36

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    That's good news, but no idea when the chemicals will begin shipping to the US, I suppose?

  7. #37
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    What you might want to do is post your question at Cafe ILFOPRO. It's dedicated forum to Ilford products and has an Ilford rep, I think, posting regularly.

    Art.
    Visit my website at www.ArtLiem.com
    or my online portfolios at APUG and ModelMayhem

  8. #38

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    Thanks, Art. I notice a few APUGers on that forum, too.

    Skip.

  9. #39
    Dug
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    Cafe Ilfopro never really got off the ground in the Ilfochrome area. These discussion boards need a certain amount of people to get going. The best information I have about Ilfochrome is actually an out-of-print Cibachrome book from the 70's. Ctein's book "Post Exposure" and Bruce Barnham's book have a bit of discussion of filtering.

    I'll keep y'all posted when Rainier Photo gets a shipment of P-30.

  10. #40
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    Quote Originally Posted by Dug
    Cafe Ilfopro never really got off the ground in the Ilfochrome area. These discussion boards need a certain amount of people to get going.
    I don't know. It has several thousand posts and most topics and threads appear to have posts with the past day or two. Seems like it has achieved some critical mass. Maybe a slow start. To be honest, I hardly check there myself, but when I did this past weekend, I was pleasantly surprised to the content.

    Art.
    Visit my website at www.ArtLiem.com
    or my online portfolios at APUG and ModelMayhem

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