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  1. #141
    Vaughn's Avatar
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    I do not know exactly is in the B&S gelatin. The temp. support material is also interesting, as it does seem to have some kind of coating on it that might help it release from the gelatin -- I just don't know much about it. I have considered re-using some of the B&S temp support, but in the processing, the slick stuff on its surface seems to come off so I haven't tried to coat it.

    Clearing -- way back when several of us were communicating via a list sort of thing (pre-internet forum style), we batted around the need for clearing and at one point decided that it was not needed. At the time I was clearing in Potassium alum...a 5% solution for 10 to 15 minutes right after developing. The solution would be slightly yellow at the end of the session.

    Further research into old prints by Dick Sullivan and others seemed to show that with single transfers, there is some dichromate trapped between the gelatin and the final support. And if the dichromate was not cleared, the dichromate continues to react with the gelatin. Over time (a long time) the gelatin can become brittle and more prone to cracking if the print is bent.

    Double transfers allow the dichromate to wash off easier during the process.

    Even with very long wash times and clean looking whites, I have found that clearing with Sodium bisulfite reduced the warmth of the print. It is the whites where there is very little gelatin -- and thus less gelatin to hold the residual dichromate (and easier to wash out). It will be the darker tones where the gelatin is thicker that will have the most dichromate and have the greater yellowing of the image.

    Streaking -- I believe Sandy is referring more to an oil-slick looking type of streaking, rather than the more regular pattern on your print.
    At least with LF landscape, a bad day of photography can still be a good day of exercise.

  2. #142
    Jim Fitzgerald's Avatar
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    Clearing white in carbon prints can be problematic. Your work flow has to be very good. I am now having much better success with this. It is a combination of factors that each of us has to adjust to their work flow. I do think that the stress pattern does come from something in the pigment along with the dichromate, exposure and even the pigment load. There are many factors. As my good friend Vaughn told me early on make adjustments one at a time and keep good notes and you will figure it out. The attached image is from Yosemite in March just after the huge snow storm. The whites are nice and clean with just a tad of pigment particles but not so much as to be distracting. The actual print shows less pigment in the highlights than the scan.
    Attached Thumbnails Attached Thumbnails El-Capitan-Oak,-Sentinel-Do.jpg  

  3. #143
    ghostcount's Avatar
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    Wow Jim! Nice clean skies! I suppose more printing experience will yield better results. Good thing making tissues is cheap.
    “I drank what?” - Socrates

  4. #144
    Vlad Soare's Avatar
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    Vaughn, you were right. They were indeed stress marks. I reimmersed the print in hot water and left it face down for half an hour, then let it dry overnight. All streaks are gone.

    I'll try a clearing bath later today, to see if it gets rid of the warmth, at least partially.
    Clearing the skies might be a problem when you use normal paper for your final support, which can absorb some dichromate. So far I've always got perfectly white highlights, probably because my final support was a fixed out RC photo paper, whose plastic base didn't absorb chemicals. When I have the process under control I'll try to use drawing or watercolor paper, and I'll probably start having clearing problems, too.

  5. #145
    artonpaper's Avatar
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    All photo sensitive compounds, the way I understand it it, produce less contrast as they become more sensitive to light. No dichromate, no sensitivity. A little and only the deepest shadows where the negative is clear will begin to expose. As the exposure gets longer, the less dense areas continue to expose and the dense areas are still without tone. This is the typical high contrast look. More dichromate will make the tissue (or gum mixture) faster, producing middle tone and highlight exposure sooner after the shadows have darkened.
    Last edited by artonpaper; 04-22-2011 at 12:47 AM. Click to view previous post history.

  6. #146
    Vlad Soare's Avatar
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    I tried to clear the print in a 3% potassium metabisulfite for ten minutes. There's no visual indication of any clearing having taken place. The print looks exactly the same (at least as far as I can tell without having another print to compare it with), and the clearing bath has remained totally colorless.

  7. #147
    Vaughn's Avatar
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    Great! One problem solved, and one possible cause of another problem eliminated! I'd call that a good day!

    Time for bed for me!

    Vaughn
    At least with LF landscape, a bad day of photography can still be a good day of exercise.

  8. #148
    Jim Fitzgerald's Avatar
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    Experience is key to carbon printing. You need to print a lot! Then things become clear!

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