HIPPOLYTE BAYARD direct positive process
Has anybody tired this ?
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 (Sodium thiosulfate) hyposulfite of soda and dried.
The resulting image was a unique photograph that could not be reproduced.
Due to the paper's poor light sensitivity, an exposure of approximately twelve minutes was required. Using this method of photography, still subject matter, such as buildings, were favored. When used for photographing people, sitters were told to close their eyes so as to eliminate the eerie, "dead" quality produced due to blinking and moving one's eyes during such a long exposure.
is the paper still wet (from the iodide) during exposure?
Kodak manufactured a direct copying film that worked in a similar way, and I think EFKE still make a direct positive paper which is sold by Freesyle. They still need developing though.
sorry I dont have have that info
Originally Posted by phritz phantom
do you think it should be wet ?
i have no idea... this is the first time, i've heard about that process.
Originally Posted by brucej
if you'd soak it in iodine, it gets wet, which would be rather impractical to have inside the camera. but i don't know if the process allows a intermediate drying.
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Originally Posted by Ian Grant
"professional duplicating film" was a single step ( negative to negative or positive to positive ) film that kodak sold but stopped making.
photowarehouse sells the same thing .. it is very slow, like azo paper,
and requires a floodlight to expose (i have used a 300W bulb) it would be between 7 and 10 stops slower than conventional photo paper, rated somewhere
between asa 6 and 25 ... and it is processed in paper developer ...
some folks have had very good results shooting the efke paper.
on the large format forum there are a handful of recent posts that look very nice.
I tried this with standard photo paper and got ... intresting results but nothing useable for
I may have to experiment with the time of preexposure and the type of
Developer. Maybe a ...surface -developer?(<-don´t know the word for it) would work better than RODINAL.
TALBOT described the Iodide-method in combination with his calotype
I hope you can understand my english
Last edited by GCyberfish; 02-21-2009 at 02:05 PM. Click to view previous post history.
An advantage of the process was that the papers could be prepared before use and stored up to one month. So I guess they were dry.
Originally Posted by phritz phantom
Still I am very interested to get this information confirmed (or infirmed) as I would like to try the process if the paper is indeed dry when I put it into the sheet holders.
Did any one of you tried the process in practice? (Bayards one, please no further references to what more or less similar can be obtained on the market. I am interested in this as a method to prepare my own photosensitive material.)
I think it could be very usefull for static models (arhitecture, maybe nature too). Bayard reached 12 minutes for an exposure, that is not too bad.
The paper has to be exposed wet. The process only works in the presence of light, oxygen and water.
Originally Posted by Eugen Mezei
Like most halogen based processes they work faster when wet, but will still work when dry, but at a slower rate.
Originally Posted by c6h6o3
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