Hippolyte Bayard direct positive process chemistry?

Discussion in 'Alternative Processes' started by Marco B, Aug 26, 2010.

  1. Marco B

    Marco B Member

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    There have been a few small APUG discussions about Hippolyte Bayard's direct positive process as described in the excerpt from Wikipedi below, but none of them actually explain how it works. Why does the addition of Iodide lead to bleaching of already formed printed out silver under influence of light, so as to reveal the positive image? Is there someone who can explain the chemistry behind this? And also how he managed to get relatively good contrast images without development, while modern day direct positive papers all need development?


    From wikipedia:

    Hippolyte Bayard (20 January 1807 – 14 May 1887) was one of the earliest photographers in the history of photography, inventing his own photography process known as direct positive printing and presenting the world's first public exhibition of photographs on 24 June 1839.
    The direct positive process involved exposing silver chloride paper to light, which turned the paper completely black. It was then soaked in potassium iodide before being exposed in a camera. After the exposure, it was washed in a bath of hyposulfite of soda and dried.

    Marco
     
  2. jnanian

    jnanian Advertiser Advertiser

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    hi marco

    i have a feeling i am not going to be any help for you,
    but with a very long exposure ( i mean hours )
    will a modern direct positive paper yield a positive image ?

    depending on the kind of day and the light, i have gotten very good
    in-camera negative images on regular photo paper ( not direct positive )
    i have exposed 30 minutes to 3 hours and depending on my subject i get
    more blue light, more exposure, less time ...

    perhaps his direct positive was the same way, a very long exposure , and a fix bath.

    my last 2 images in my gallery are from negatives made this way.
    no-chemistry, just sunlight and photo paper.
     
  3. Marco B

    Marco B Member

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    By the way, I also saw a reference in Naomi Rosenblum's "A World History of Photography" to a direct postive "cyanotype" process. Now I have read before about the difference between blueprints (negative/positive process) and bluelines (direct positive needing development in ammonia fumes). See this Photo.Net thread: http://photo.net/black-and-white-photo-printing-finishing-forum/00WhAQ and especially the remark by Kelly Flanigan.

    Is there someone who has more info or links on Hippolyte's direct positive cyanotype process, and especially the chemistry behind it?
     
  4. Marco B

    Marco B Member

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    Interesting results John, I would never have expected such blue prints. I have seen paper out of the box go purplish in my darkroom after hours, but not so blue... Maybe it is because the strong sun light helps getting rid of the halides as gas once they have exchanged their electrons with the silver cations to form silver?
     
  5. Photo Engineer

    Photo Engineer Subscriber

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    You know that I make a lot of silver chloride emulsions, but the best I can do with strong exposure is a medium to dark purple on prolonged exposure. I wonder if there is more to it than that. There usually is, unfortunately, as many early workers kept their formulas secret.

    PE
     
  6. jnanian

    jnanian Advertiser Advertiser

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    well ...

    there was nothing more to it than polymax single weight fiber paper that is long expired ..
    a box camera and the sun. i can't speak about gases being emitted and silver cations ...
    all i can say is that there is something interesting about just plain old photo paper and
    how it can be exposed for a short burst of light and yield a beautiful image, or
    a long period of time, and yield an image ..

    maybe the secret is there is no secret at all it is just a long exposure
    that monsieur bayard did, and everyone just figures that it was a short exposure because,
    many other emulsions were short exposures ....
     
  7. Igor Savchenko

    Igor Savchenko Member

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  8. Photo Engineer

    Photo Engineer Subscriber

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    Ahhhhh, wet! That can make a big difference!

    Thanks.

    PE
     
  9. mabman

    mabman Member

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    I find this interesting - can you elaborate a bit on your process? Are you rinsing/wetting the paper before putting it in fixer?
     
  10. Curt

    Curt Subscriber

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  11. Marco B

    Marco B Member

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    We now have a serious conflict. One description suggests the potassium iodide bath was done before, and the other after the exposure. A significant difference... :unsure:

    In addition, the first description suggests the paper was darkened completely before the exposure and bleached during the exposure to reveal the image..., while the second suggests the darkening took place while exposing and the image revealed afterwards?!...

    Anyone else who can elaborate on the direct positive processes Hippolyte applied (both the silver version and/or the cyanotype version) and especially the chemistry going on during the processes?

    Interesting book by the way you referenced Igor (http://www.christopherjames-studio.com/build/thebook.html). I am surprised Christopher's book is not listed on the Alternative Photography website as well... might be a nice addition.

    Ah... well, it is listed, but not on the "Books" main page, but under "Amazone books":
    http://www.alternativephotography.com/wp/book/amazon-books
     
    Last edited by a moderator: Aug 27, 2010
  12. Marco B

    Marco B Member

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    Well, as usual, even though I was not even searching for this specific Hippolyte Bayard process at all, browsing the internet I hit on the work of Tania Passafiume for the George Eastman House back in 2001...

    Seems she dug into the direct positive process and Bayard quite deeply. Haven't had the time to really go through this 64 page PDF document, but it sure seems interesting enough:

    http://notesonphotographs.eastmanhouse.org/images/0/08/Tania_Passifiume_Bayard_for_web.pdf

    Reading some comments though, it seems quite clear that the potassium iodide was applied before exposure, see the "What is the chemical reaction?" section on page 7.

    Tannia also shows some detailed instructions for re-creating the process.

    I think some of you that seem to be following my posts here on APUG are going to love this document! :wink:

    Marco
     
    Last edited by a moderator: Sep 9, 2010
  13. michaelbsc

    michaelbsc Member

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    How did you know I was following this?
     
  14. jnanian

    jnanian Advertiser Advertiser

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    hi mabman

    what i did was just take a long exposure through a camera ..
    my box camera has a time-setting, so i opened the shutter
    and left it for about 1/2 hour-40 mins ..
    the negatives ( or positives if i contact print a negative this way )
    are kind of delicate. the ones i fixed were in a water bath first
    then partially exhausted speed fixer and the images bleached quite badly.
    i have a recipe for a weak hypo bath for sun prints someone gave me
    that i will use next. i haven't had time to make more exposures to test
    the hypo ...
     
  15. jnanian

    jnanian Advertiser Advertiser

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    hi marco,

    thanks for this nugget !
    it was a great thing to read about :smile:
    (and maybe do? ) :smile:
    john
     
  16. Gerald C Koch

    Gerald C Koch Member

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    IIRC, the H&D curve for certain emulsions eventually flattens out and then reverses direction with increased exposure. In this latter region density actually decreases with increased exposure.
     
  17. jnanian

    jnanian Advertiser Advertiser

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    hi jerry

    if the paper was not pre-exposed black prior to exposure ..
    but still coated with the iodide, do you think it would it be a faint negative image,
    ... like an ambrotype?

    i'm relatively clueless
    but ... it seems that what bayard did was make a reversed+fixed version of nicéphore niépce's
    unfixable - lumen / retina prints.
     
  18. Photo Engineer

    Photo Engineer Subscriber

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    Jerry;

    You are correct. All emulsions today are treated in some way to emphasize or repress one of those images, neg or pos.

    PE
     
  19. cliveh

    cliveh Subscriber

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    Hippolyte Bayard was not the only one to experiment with a direct positive process, particularly after the advent of the Daguerreotype. Fox Talbot thought that this may be the way to go, thus not realising at the time the full advantage of his own replication process. I would suggest from my own research in this area, that fogging with the first halogen was followed by expose with a second. This is a very interesting area for practical research and one which promises many possibilities for new forms of chemical imagery.
     
  20. Gerald C Koch

    Gerald C Koch Member

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    As am I. It has been decades since I have read anything on the subject. The illustration of the H&D curve sticks out in my memory but little else.