Why didn’t this months-long contact exposure go completely black?

Nodda Duma

Member
Joined
Jan 22, 2013
Messages
2,685
Location
Batesville, Arkansas
Format
Multi Format
I performed an interesting experiment where I contact printed a negative onto a silver gelatin emulsion coated piece of glass by placing it in the sun for many months. The experiment could have been performed with paper or film but I happened to use one of my dry plates.

This weekend I processed the plate by fixing it with no use of developer. The result was pretty cool but the question is... why was there any image at all? Even through the dense parts of the negative, the plate received plenty of sunlight. One would think the density would have leveled out to the same amount regardless of shadows or highlights.

Shown are scans of the results and the original negative, and a photo of the plate itself.





 

Kino

Subscriber
Joined
Jan 20, 2006
Messages
7,759
Location
Orange, Virginia
Format
Multi Format
Would this be a case of physical development over photographic development?

"In physical development, the metallic silver specks in the photosensitive layer also serve to catalyze the reduction of silver nitrate in the developer. In one type of physical development, the exposed photosensitive material is subjected to photographic fixing; only the specks of metallic silver then remain."

https://encyclopedia2.thefreedictionary.com/Photographic+Development

Just a guess...
 

removed account4

Subscriber
Joined
Jun 21, 2003
Messages
29,832
Format
Hybrid
Hi Jason !

Welcome to the world of sun printing
What surprises me is that you were able to fix the image with out the plate losing it. ( sometimes I develop the plates I have in carbonate rich caffenol before I fix them and it sometimes works ) I've been making sun prints like this on film and glass and metal and paper, but not for months of exposure for a day or two sometimes, or a multiple hours usually, and the plate turns white when it is fixed if it isn't treated with caffenol first. I don't know the chemistry or the reason it does what it does but I enjoy doing it because it goes back to the original days of photography. Maybe the emulsion you used had excess Silver Nitrate ( like POP emulsion ), so you were able to expose and fix it and have it look normal. When I do it, I usually have to fiddle with it a little (levels) in PS and the image has a deep blue color. ( When Joseph Nicéphore Niépce did these originally he used salted paper and Silver Nitrate, and he couldn't figure out how to fix the images ).

Have fun
John
 
OP
OP

Nodda Duma

Member
Joined
Jan 22, 2013
Messages
2,685
Location
Batesville, Arkansas
Format
Multi Format
This was my dry plate emulsion, so no excess silver nitrate. Silver nitrate is added to an excess of salt during precipitation stage. Then of course the emulsion is washed, etc. etc. So just like a very fine-grain B&W film.
 
OP
OP

Nodda Duma

Member
Joined
Jan 22, 2013
Messages
2,685
Location
Batesville, Arkansas
Format
Multi Format

I didn’t run it through a developer.
 

Kino

Subscriber
Joined
Jan 20, 2006
Messages
7,759
Location
Orange, Virginia
Format
Multi Format
I guess your plates are acting like Printing out paper...
 

nmp

Member
Joined
Jan 20, 2005
Messages
2,017
Location
Maryland USA
Format
35mm
Without development, it is just the latent image. Precisely because it is not POP (no excess silver nitrate) it didn't turn all black. In absence of excess nitrate, the conversion to silver metal is very slow. If I am not mistaken, the plates are slow to start with having an ISO 10 or so.
 

removed account4

Subscriber
Joined
Jun 21, 2003
Messages
29,832
Format
Hybrid
Jason

I am not sure if you have ever heard of solargraph, but they are long exposed photographs using a pinhole camera ( Instead of a contact print in the sun for days) , mounted someplace for 6 months to record the path of the sun. These images usually can't be developed or fixed but NedL has figured out a way to fix them.
https://www.photrio.com/forum/resources/how-to-fix-a-solargraph.72/
You are lucky your image hasn't faded or turned grey slowly ( or turned completely white when you fixed it!!) because usually that is what happens. ( I sometimes put my unfixed sun prints in a box in a drawer that is dark, and I have a whole drawer full of grey sun prints ). Have fun !

John

ps. i just uploaded this one https://www.photrio.com/forum/media/sun-print-xerox-negative-photo-paper-positive.59959/
exposed for IDK 8 hours?
 
Last edited:
OP
OP

Nodda Duma

Member
Joined
Jan 22, 2013
Messages
2,685
Location
Batesville, Arkansas
Format
Multi Format
I just checked and the image is still there.

I wonder if one of the toners like selenium toner could preserve the fading images you mention.
 

removed account4

Subscriber
Joined
Jun 21, 2003
Messages
29,832
Format
Hybrid
you mentioned you fix your image .. what sort of fixer did you use? plain old hypo? hypo spiked with sodium carbonate like a POP fixer? speed fixer? watered down fixer like people do with lumen prints? i asked because if you fixed it and it didn't lighten or fade &c you might not have to treat it with toners...

I've tried "save" ones from store bought paper and film using AG-STAB unsuccessfully ... I was in touch with Wolfgang Moersch years ago
when I started doing these prints ( began doing them in camera ) and he suggested that because they were a "stain" not an actual chemical reaction
like lumen prints it would be difficult to preserve them. I also asked PE about preserving them and he was not able to offer any help...

I have to admit that with home made emulsion ( or store bought liquid stuff ) and matte finish RC papers, I'm not sure why, but, I have had less trouble with them them fading fast, I have some rc prints that are weeks old and still purplish like they were just made. It must have to do with additives and complex chemistry put into the paper or emulsion. I think with a lot of things, simple works best...

That said, the article I linked to ( NedL's ) about preserving solar graphs is the real deal he's done it often ..

Good Luck !
 
Last edited:
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…