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what causes bronzing degradation of a silver print?


Mine were also framed. For what it's worth, I had some prints displayed in the same office which showed similar degredation that was some kind of Mitsubishi paper I got used. I don't think I've seen any deterioration on any RC print that was not framed. I also tend to "overwash", leaving my prints in a soak tank until the end of the session, and I use film-strength rapid fixer. I do not routinely use 2-bath fixing, though, and also no toning.

Why do framed prints deteriorate more? Should we be venting our frames better?
 
Ok then, ignore my post. All of the answers are in the Ctein article, which is downloadable.

PE
 

Yes Bob, I have prints from the same session that are fine - which leads me to believe that it's most probably caused by the cheap frame imports, as Simon described above.

I actually bought Sistan when I first noticed it, and used it regularly; unfortunately I no longer have any left so I'll need to investigate the other products mentioned up-thread. In the meantime, I've been toning in 1:20 Selenium for a few minutes, which.
 
Ctein wrote the book post exposure. I have the printed version. It may be downloaded as pdf:
http://ctein.com/PostExposure2ndIllustrated.pdf
Please read the section starting at p. 158.

Short version: Baryta papers have a baryt layer between paper and the photographic layer. This impractical for RC papers. Instead the resin layer is brightened with titan dioxide, TIO2. This reacts with the silver and gives the reaction you got: "Silvering out".

If we believe the manufacturers modern papers overcome this problem by a modified resin layer. RC papers of one manufacturer (foma) had the problem at least until two years ago. I lost some exhibition prints and switched to another manufacturer.

Silvering of RC papers cannot be avoided by prober fixing. It may be avoided or at least decelerated by toning or using Sistan. I fo myself make exhibition print on baryta now. Slightly more expansive, remarkably more elaborate but long time stable.
 
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ozphoto said:
I'll check out the article - could make for interesting reading as you said, PE.

Edit: I'm having a hard time finding the article; anyone have a link for it???
Click to expand...

I believe everyone is talking about Ctein - Post Exposure.

pdeeh: I agree, it is somewhat beautiful, I'm just concerned that I'm going to end up with no picture shortly and in any case, not the one I thought I printed! If it were a proportional effect wrt silver density and archivally stable, I'd be chuffed.

Simon: thanks for replying. I'll note that none of my Ilford or Kentmere prints have suffered this fate!
 

OK, that's now three or four of us in just this thread, with this problem with Foma RC. A pity, as I have quite a stash of it!
 
I had this bronzing show up just a few years after printing my Stepmother's bridal pic from 2001--the first time I ever saw it. I had printed it 20x24 on Ilford Multigrade RC. Had never seen this effect before. BTW I had selenium toned this print, inasmuch as this paper was not toner-friendly.. It bronzed in the dark areas anyway
 
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Thanks to all of you who provided the link - it made for *extremely* interesting reading, and as I now use Selenium toner in all my prints, I'm hopeful this problem will now be behind me.

Interesting the dates that Ctein mentioned - mid 90s as that is around the time the Agfa paper I was using would have been manufactured, and it was also their Multicontrast RC.

Obviously the damaged prints are now beyond saving, however if I were to use selenium toner on the prints that are currently in storage, would I be correct in thinking they would then be perfectly ok for presentation and display?

Edit: Does anyone in AU know who the wholesaler is for (New) Sistan?
 
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ozphoto said:
Edit: Does anyone in AU know who the wholesaler is for (New) Sistan?
Click to expand...

The successor for Sistan is obviously Adolux Adostab . It is sold by ADOX/Fotoimpex .
I have also noted an interesting thing in my own contact sheet archive. From the late seventies and early eighties I have a mixture of contact sheets on both RC-paper and baryta paper. several of them show signs of bronzing, but it only occurs on the RC-papers. None of the baryta papers are affected. I have a feeling that the instructions for washing RC-papers were a bit optimistic when they were new on the market. Nowadays I don't use any RC-papers and about two years ago I celebrated when I finished the last RC-paper carton.

Karl-Gustaf
 
I know that modern EK RC papers and some others contain antibronzing agents which appear to work. Quite a lot of R&D went into making it work AAMOF.

PE
 
I've always loved the way certain antique poorly-fixed silver prints have differentially (though unintentionally) bronzed or otherwise discolored
over the decades. Nowadays we can have our cake and eat it too, doing that kind of thing split-toning, while improving permanence at the
same time.
 
(I probably did misuse that term. "bronzing" ... was obviously referring to a hue rather than sheen effect)
 
This all piqued my interest and I did a few searches for other APUG threads on the subject, and there are quite a few. A couple mentioned a test IPI developed that involved exposing a print to Hydrogen peroxide fumes, and being of the "I wonder what would happen if ..." persuasion, found a (very) scrap print on RC and taped it over a tray in which I had laid a sheet of paper moistened with 6% peroxide. I left it, wrapped in a plastic bag, for a few days, and this is what came out of the bag today.

Please note that this is not intended as any sort of controlled test, plus the print was probably neither fixed not washed properly, so no conclusions are being drawn! But I thought it might interest one or two of the contributors.
 

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Without knowing the original image, that effect does look quite similar. And that's as you would expect: it seems that this effect is due to oxidation of silver freeing up Ag+ ions to migrate through the emulsion. Once freed, they either get reduced by some sulfide in the air (producing the bronze look) or they make it to the surface of the emulsion and reduce to metallic silver (producing the mirror look).

Any oxidising agent should be capable of liberating Ag+ ions, and peroxide certainly is a good oxidiser! I suspect that H2O2 fumes might also cause rapid damage to FB prints - any unprotected (no toning, no sistan) silver print in an oxidising environment like that is going to suffer badly. You can see plenty of degraded FB prints that have silvered out, the conservators believe due to exposure to oxisiders including high moisture content in the air.

The supposition behind what I've been reading (and have heard back from the conservators that I emailed) is that RC prints are unusually vulnerable because the TiO2 brightener can act as an oxidiser when exposed to light, as can (perhaps) fumes released from the coatings on the paper. So while a framed FB print will be in a nice clean environment, an RC print itself produces one or two different oxidisers that can liberate silver ions for migration, and that can start occurring within a few months if the print is behind glass, trapping the fumes. I suspect that manufacturers like Ilford have perhaps solved this problem with their papers, as the recent (2005+) reports seem to concern only Foma RC papers and, anecdotally, all my Ilford & Kentmere prints are fine.
 

i love how old polaroid b/w images do / did this. i looked forward to watching them change
 
The whole RC question is interesting, and firm answers seem hard to come by. I never use RC papers myself except for short-term commercial
work. Some examples of these have been put in portfolios and still seem fine. But all my personal work, and anything intended for display, has
always been done on fiber-based paper. I should probably donate some prints to people on the "bad side of the tracks", namely, upwind from
the oil refinery, where sulfur dioxide leaks are still frequent. Maybe that would replicate some of the effects I've seen on 19th C prints, at least if I failed to tone mine. Certain otherwise boring old prints have become magnificent due to random color and sheen changes, including "bronzing". Whether they've tarnished to completion, or will deteriorate even more, is something I'll probably never know. Copper-toned prints
certainly discolor quickly, just like a penny.
 
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