Extreme long exposure with Paper

[Tim Gray]

I live in a small studio apartment - not the hip kind. Anyway, my enlarger normally lives on the floor next to the window. I usually have a couple of sheets of photo paper (Ilford RC) in the baseboard. These sheets were messed up exposures (forgot to stop down the lens, etc.) and so I use them for focussing and other purposes.

I've noticed that these sheets turn dark tan and depending on what parts are covered, sometimes yellowish, greenish, or pinkish (all with a tan cast to them). I'm talking about exposures of days-weeks. My questions is this: Is there anyway to preserve this exposed paper and stop further changes? I would imagine if I developed them, they'd turn pitch black. Should I fix them?

Also, what causes the black and white paper to color?

I guess I should try this next time I print, but figured someone might know. I'm curious because I'm interested in sticking some paper in some pinhole cameras and letting them expose for extremely long periods of time.

 

[Jadedoto]

Tim,
From what I understand, the discoloration is occurring because modern papers usually include some sort of developer in the emulsion. This is the reason papers don't keep for too awful long (with some exception); the purpose of this is to aid in the actual development of the paper, making the image pull through the RC paper faster than it would otherwise.

Personally, I'm not one to like the whole incorporated developer thing, although I'm sure there's a real reason it was included... Perhaps to increase sales of paper and prevent long term storage? Me not burning through paper, I find it more of an annoyance than anything.

Fixing the paper would probably be a more cosmetic thing than anything- and developing them to black as well. The discoloration shouldn't hurt anything.

Did one of them have the image of Jesus in it by any chance? Might catch a good deal on the auction site!

Vince

 

[Tim Gray]

Certainly no images of Jesus at this point. More of photograms depending on what was left on the paper (by accident).

The colored aspect of it makes me want to try taking some images with a pinhole. It's an interesting palette, but it would be shame if I couldn't somehow make the image semi-permanent after a 3 week exposure by fixing... Or some other process.

 

[Ole]

It's the same phenomenon that is used in Printing-out-papers: The halides darken directly as a result of exposure, even without developer. It's got absolutely nothing to do with any developer in the emulsion.

Enlarging papers are not really good for this, so you might think of getting some real POP?

 

[Tim Gray]

Is POP still made? Would have ridiculously long exposure times like normal paper? I kind of like the idea of taking weeks-long or months-long exposures...

 

[Shawn Dougherty]

Is POP still made?

It sure is, check the following link.

albumenworks.com

 

[Jadedoto]

It's the same phenomenon that is used in Printing-out-papers: The halides darken directly as a result of exposure, even without developer. It's got absolutely nothing to do with any developer in the emulsion.

Enlarging papers are not really good for this, so you might think of getting some real POP?

Interesting, for some reason I recall always hearing about the developer being incorporated making the storage life shorter. I guess you'd be right then, short term exposure like that wouldn't affect it. Should've thought about that- it's my senior project studying this stuff. D'oh!

 

[fschifano]

Vince's explanation about why the paper darkens on its own is right on the money. Unfortunately, there is nothing you can do to preserve that look. The paper will reach an equilibrium where it won't darken any more, but the whole thing will darken eventually. If you fix them out, they'll revert to the base white color and be stable. You can still use them for focusing. If you develop one or two sheets out to black, they can be cut into handy dodging tools. Use the black side down.

 

[Michel Hardy-Vallée]

Funny thing, I had noticed the same thing with the pieces of paper I use to put under my grain focuser:

(there was a url link here which no longer exists)

When I fixed the papers, I noticed that most, if not all of the colour disappeared, which suggests to me that it's a printing-out process happening very slowly.

Next time I'll try to tone in selenium before fixing to see if it preserves the colour more.

 

[Ole]

Note: I haven't actually tried this, but I've used a fair bit of POP:

Selenium toner contains ammonium thiosulfate, and will bleach away the colour you wanted to preserve.

Gold toner is very expensive, but was (and is) the preferred toner for POP. Follow (or preceed) with fixing in dilute sodium thiosulfate. Do NOT use rapid fixer. I sometimes use a rapid fixer diluted 1:10 from working strength it I want to clear the highlights of POP...

 

[Roger Hicks]

Gold toner is very expensive, but was (and is) the preferred toner for POP. Follow (or preceed) with fixing in dilute sodium thiosulfate.

Platinum toning is even nicer in my view (and of course even more expensive): the top three pics in the posted link are platinum toned POP. To return to your advice, I immediately thought of the same thing, but with any toner, there will still be colour shifts in both toning and fixing the printed-out non-POP paper, so you will need a LOT of experiment. I've seen this done apparently successfully, with (for example) pale violet images, I think in Ed Buziak's old Darkroom User magazine, but it's a lot of work.

Link to platinum-toned POP: http://www.rogerandfrances.com/sgallery/g sl m 1.html

 

[Steve Smith]

I'm not an expert so I may be wrong (probably!) but based on what I have read, it is my understanding that the purpose of developer is to intensify the weak latent image to the point where it has an effect on the emulsion.

If you supply enough light then the development stage is not needed and the paper can go straight into fixer after exposure. Isn't this what POP does?

As for exposure with a pinhole though, you may be looking at exposures measured in months or years!

Steve.

 

[Tim Gray]

Thanks for all the info!

 

[rwyoung]

Vince's explanation about why the paper darkens on its own is right on the money. Unfortunately, there is nothing you can do to preserve that look. The paper will reach an equilibrium where it won't darken any more, but the whole thing will darken eventually. If you fix them out, they'll revert to the base white color and be stable. You can still use them for focusing. If you develop one or two sheets out to black, they can be cut into handy dodging tools. Use the black side down.

Not quite true on the fixing. If you use plain HYPO, it will bleach back a little bit but mostly it will retain the image. RAPID FIXER has a much stronger bleaching action.

I have several examples where I placed a 4x5 negative and some photo paper (Ilford, Foma, Forte and Kodak were played with) in a contact printing frame and gave it either 30 minutes in the noon-day sun or about 1 hour on my UV box. You get some neat colors, peachy browns, purples, green-gray. They all bleached back a touch in the fixer but otherwise held the contact print just fine.

I should note, these were all RC papers except for some old Kodabrome postcard paper which was fiber.

 

[rwyoung]

As for exposure with a pinhole though, you may be looking at exposures measured in months or years!

I can't find the link, and I may never find the link but I did read about an "artist" who had built himself several small pinhole cameras from brass tube. Inside he placed black construction paper and then fixed the small cameras to the sides of buildings. The intention was for months to years of exposure onto the black construction paper.

The UV should bleach out the paper to form an image.

 

[Steve Smith]

I can't find the link, and I may never find the link but I did read about an "artist" who had built himself several small pinhole cameras from brass tube. Inside he placed black construction paper and then fixed the small cameras to the sides of buildings. The intention was for months to years of exposure onto the black construction paper.

I read an article on this a few years ago. Some of his images showing the multiple passes of the sun, each one offset a bit from the previous one, were quite interesting.

I seem to remember he used some fairly strong ND filters too to increase the exposure time even further.


Steve.