Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,965   Posts: 1,558,398   Online: 800
      
Page 1 of 2 12 LastLast
Results 1 to 10 of 20
  1. #1
    Marco B's Avatar
    Join Date
    Jan 2005
    Location
    The Netherlands
    Shooter
    Multi Format
    Posts
    2,983
    Images
    169

    Hippolyte Bayard direct positive process chemistry?

    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
    My website

    "The nineteenth century began by believing that what was reasonable was true, and it wound up by believing that what it saw a photograph of, was true." - William M. Ivins Jr.

    "I don't know, maybe we should disinvent color, and we could just shoot Black & White." - David Burnett in 1978

    "Analog is chemistry + physics, digital is physics + math, which ones did you like most?"

  2. #2

    Join Date
    Jun 2003
    Shooter
    Multi Format
    Posts
    16,564
    Blog Entries
    3
    Images
    8
    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. #3
    Marco B's Avatar
    Join Date
    Jan 2005
    Location
    The Netherlands
    Shooter
    Multi Format
    Posts
    2,983
    Images
    169
    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-pho...g-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?
    My website

    "The nineteenth century began by believing that what was reasonable was true, and it wound up by believing that what it saw a photograph of, was true." - William M. Ivins Jr.

    "I don't know, maybe we should disinvent color, and we could just shoot Black & White." - David Burnett in 1978

    "Analog is chemistry + physics, digital is physics + math, which ones did you like most?"

  4. #4
    Marco B's Avatar
    Join Date
    Jan 2005
    Location
    The Netherlands
    Shooter
    Multi Format
    Posts
    2,983
    Images
    169
    Quote Originally Posted by jnanian View Post
    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 ...
    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?
    My website

    "The nineteenth century began by believing that what was reasonable was true, and it wound up by believing that what it saw a photograph of, was true." - William M. Ivins Jr.

    "I don't know, maybe we should disinvent color, and we could just shoot Black & White." - David Burnett in 1978

    "Analog is chemistry + physics, digital is physics + math, which ones did you like most?"

  5. #5
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,214
    Images
    65
    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. #6

    Join Date
    Jun 2003
    Shooter
    Multi Format
    Posts
    16,564
    Blog Entries
    3
    Images
    8
    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. #7

    Join Date
    Dec 2006
    Location
    Belarus
    Shooter
    Multi Format
    Posts
    36
    From another source http://www.christopherjames-studio.c.../PinholeSm.pdf : “Bayard coated his paper with silver chloride and inserted the moist paper in his camera for a lengthy exposure. Following that, he immersed the darkened print in a bath of potassium iodide to yield a positive image that he fixed in potassium bromide.”

  8. #8
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,214
    Images
    65
    Ahhhhh, wet! That can make a big difference!

    Thanks.

    PE

  9. #9

    Join Date
    Jun 2007
    Location
    Winnipeg, MB, Canada
    Shooter
    35mm
    Posts
    830
    Quote Originally Posted by jnanian View Post
    well ...

    there was nothing more to it than polymax single weight fiber paper that is long expired ..
    a box camera and the sun....
    I find this interesting - can you elaborate a bit on your process? Are you rinsing/wetting the paper before putting it in fixer?
    i can't wait to take a picture of my thumb with this beautiful camera.

    - phirehouse, after buying a camera in the classifieds

  10. #10
    Curt's Avatar
    Join Date
    Sep 2005
    Location
    Pacific Northwest
    Shooter
    Multi Format
    Posts
    4,553
    Images
    15
    The French government gave too much attention to that other guy, Mr. Daguerre, so the picture on the other side of this paper is that of Mr. Bayard who drowned himself.

    He once made a self portrait showing him having drown with the caption on the back.

    http://en.wikipedia.org/wiki/Hippolyte_Bayard


    Which bring to mind this poem

    http://www.artofeurope.com/smith/smi1.htm
    Everytime I find a film or paper that I like, they discontinue it. - Paul Strand - Aperture monograph on Strand

Page 1 of 2 12 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin