what causes bronzing degradation of a silver print?

Hey all,

I have a couple of prints on my wall that have started to degrade, I only noticed it when looking closely (cleaning the frames). They've started getting a reflective (the metamerism is what I noticed first) bronze appearance in the shadows/lower-midtones. It's uniform across the print (not just the edges) but definitely correlates with the denser parts. A couple of Zone-III regions have it speckled across them, and it forms dense lines of reflectivity where light & dark parts of the print meet. The darkest regions don't seem to have it and the higher zones are clear. It has a bronze appearance in diffuse light and a silvery appearance from straight-on - see attached.

The paper is Arista.EDU RC VC gloss, aka Foma Variant, developed in Ilford Multigrade 1+7, fixed for 1:00 in Hypam 1+4, washed for 4:00 (continuous agitation) with 6 changes of water. The change has occurred only (and equally) in two framed prints and other prints made in the same timeframe and stored in paper boxes have mostly not degraded; one (of maybe 20 in boxes) has bronzing over about 1/3 of its area, seemingly where it was more exposed to atmosphere. The prints are only about 20 months old. The framed prints are sandwiched between acid-free mat boards and behind glass. Not hermetically sealed. They're hung in a bedroom out of direct sunlight and the humidity is often very high due to drying clothes in front of a heater (we can get condensation on the windows) but there has never been condensation in the frames.

Being in Adelaide, I have a fair bit of iron in my process water, could that be a cause? Perhaps I have humidity-induced silver-mirroring and colouring of that due to iron?

What is the degradation and how do I avoid it? Is my portfolio of stuff printed so far mostly screwed?

</panicing>

Incomplete fixing and washing is at the top of the list.

I think I fix for longer using bath A and B (I use plain hypo 3-4 minutes in each) and use hypo clear per Kodaks instructions.

The hypo clear is cheap... and RC is more expensive than hypo.

If your locality is very industrial that can be a problem my mum 'lost' her silver plated cutlery over several decades.

If you need archival consider toning...

I would agree with markbarendt. Are you using a single fixing bath? Two is more reliable.

This print was single-bath fixed. Note that this is RC paper not FB and I'm using fixer at film-strength not paper-strength. I am therefore fixing for twice as long, or at twice the concentration as recommended by Ilford in their Hypam datasheet. I also process at 25C not 20C, so that should also dramatically increase the fixer reaction rate.

Likewise the wash, Ilford recommends 2 minutes at 5C or higher, I do 4 minutes at 25C. Again, twice the recommendation ought to be safe!

As to excess silver in solution, I use the fixer to about 1/2 its rated capacity (40 of 8x10 per L of working solution), so the silver concentration should be under 2g/L. Maybe the Foma paper is more silver-heavy than Ilford's RC offerings, but I doubt that it should be dramatically so. And if it were, then I would expect highlight yellowing due to the creation of sulfides in non-image areas, but that's not happening.

I had a read of this guide, which has this to say about underfixing/underwashing (emphasis mine):

Faulty processing results in silver-fixer compounds remaining in the print after processing. This can be the result of not enough time in the fixing bath, exhausted fixer, or not enough washing. The results are not immediately visible, but over time the fixer (sodium thiosulfate) breaks down and reacts with the silver to form small particles of yellow silver sulfide across the entire print. This weak yellow staining is generally only visible in the non-image areas and highlights, while in the midtones and shadows it is masked by the silver image. The residual fixer will decompose and react with the silver image, causing yellow/brown discoloration of the image in the highlights and midtones. If faulty processing is the cause of discoloration, silver-mirroring will likely not be seen, since the sulfur in the print reacts quickly with the silver ions, preventing their passage to the print surface

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I have the opposite problem: silvering, and totally clear non-image/highlight areas. I would go with silver-mirroring, except that the mirroring doesn't extend to the deepest shadows, it seems confined to the lower midtones. I have been abusing the prints with high and variable humidity, which can cause mirroring.

The PDF also talks of sulfide stains (from post-wash contamination), but they don't seem image-related: the examples are a fingerprint and a liquid mark. The effects in my prints correlate with the image structure, not fingerprints or blobs spilled thereon.

not sure if bronzing is the same as silvering out but
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polyglot said:

What is the degradation and how do I avoid it? Is my portfolio of stuff printed so far mostly screwed?

Click to expand...

Does it look anything like the images in this report: http://iaq.dk/image/rc_photos.htm

jnanian said:

not sure if bronzing is the same as silvering out but
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Very interesting, thankyou. Does anyone have an example of what this "silvering out" looks like? And what constitutes "gross overwashing"?

paul_c5x4 said:

Does it look anything like the images in this report: http://iaq.dk/image/rc_photos.htm

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No, the highlights are all completely clear. No yellowing except where it looks like image-silver has been ion-migrating and then both sulfiding and plating out in a mirror.

hi polyglot

hard to explain what silvering out looks like
kind of like the print has metal on the surface of it that
has tarnished. when tilted to the side it has a metallic-sheen to it.

and with regards to grossly over washing ...
according to pe you need to do a residual hypo test to see when it
"passes" and when it does, stop washing ...

if you have ag stab, you can use that to stabilize the rc prints
it is the same as sistan ( i think it is the same as sistan )
or use selenium toner to tone your rc prints ...


were your prints in frames ? i have heard that rc prints out-gas which also
causes problems ...

Well toning the next batch is an option...

But trying Farmers reducer on qtips may help a bit.

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

For what it's worth I have had silvering-out-type degradation on EDU.Ultra paper processed about 4-5 years ago. I'm not positive it's the paper at fault, but it's something to think about.

Silver, unlike gold, is subject to deterioration. It is said that 'over washing' can be bad for a print and, ironically, a tiny bit of hypo should be left in the print in order to 'shield' the silver from atmospheric effects. - David Lyga

I too have had this effect, but only in prints that I have had framed in some timber frames from discount stores. Most are on Agfa RC paper, but one is actually on Agfa Portriga. (Agfa is/was my paper of choice.) I always washed well, even my contact sheets get the "royal" treatment.

I have often wondered if perhaps a gas was given off by the varnish (?) used on the frames and this in turn was having a detrimental affect on the paper.

"hard to explain what silvering out looks like kind of like the print has metal on the surface of it that has tarnished. when tilted to the side it has a metallic-sheen to it." jnanian - describes the effect perfectly!

It has not happened to *any* of my contact prints or other prints that I have framed in more expensive, custom made frames; I've since dispensed with the offending frame - it now resides in the garage minus the prints.

jnanian said:

hi polyglot

hard to explain what silvering out looks like
kind of like the print has metal on the surface of it that
has tarnished. when tilted to the side it has a metallic-sheen to it.

Click to expand...

Thanks, that's exactly what it looks like.

jnanian said:

and with regards to grossly over washing ...
according to pe you need to do a residual hypo test to see when it
"passes" and when it does, stop washing ...

if you have ag stab, you can use that to stabilize the rc prints
it is the same as sistan ( i think it is the same as sistan )
or use selenium toner to tone your rc prints ...

were your prints in frames ? i have heard that rc prints out-gas which also
causes problems ...

Click to expand...

Two (the ones I noticed) are in frames and they have this effect all over; the frames are wooden but very old and recycled so I would have expected any gaseous nastiness to have come out of them by now. The mats are new, but they're proper 4-ply acid-free framing mats, nothing crazy. The frames previously contained 20-year-old FB prints that I removed in fine condition; the pictures just sucked I dug through a couple of paper-boxes of prints and found only one more (of maybe 20 made around the same time) print with the effect, and it was partial. All the other ones just have the slight metamerism that Foma RC Gloss has when processed, with no further visible changes.

I'm still puzzled though as to why this effect is strongest at sites where there is plenty of image silver, but only when adjacent to unsilvered areas.

Sounds like I need to invest in some Sistan, Selenium, Sepia and storage desiccant. I've always wanted to see what Selenium looked like but have avoided it due to toxicity so far.

Using something like agfa sistan (or current equivalent), or Fuji Ag Guard usually helps with RC.

BTW, there is a long read about RC troubleshooting in the –now free download– Ctein's book, Post exposure. Some is about this subject.

Here's a case that I would consider extreme. I acquired this and another a number of years ago, both exhibiting the same degree of deterioration. It appears to have migrated in from the borders which are the densest part of the print. I suspect that atmospheric conditions played a leading role here.

View attachment 90436

I expect I'm swimming against the tide here, but I think it is rather a beautiful effect ...

pdeeh said:

I expect I'm swimming against the tide here, but I think it is rather a beautiful effect ...

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me too!

rockland colloid sells a toner that offers a similar( but different) effect
(there was a url link here which no longer exists)
valerie, here on apug, has uploaded a few images that use this toner ( its called halochrome toner ) ...

David Lyga said:

tiny bit of hypo should be left in the print in order to 'shield' the silver from atmospheric effects. - David Lyga

Click to expand...

This is what heard from couple of guys (outside of APUG) for RC prints.

Bronzing is a term used to describe a migration or change in the emulsion chemical composition post processing, mirroring is also a term used, but that is more likely in relation to old prints ( 50 years + )
a 'surface' bronzing' is actually called Bloom.

Bronzing should not occur on any correctly fixed and washed print, certainly not within 5 years.

The simple reason why this occurs is contamination ( by gases ) of the emulsion surface that is accelerated by exposure to light ( and no I do not mean direct sunlight ) it can happen on FB as well as RC. It seems more prevelant in high temperature, high humidity areas than in low temperature, low humidity areas.

When it was common to have B&W photographs in hairdressing salons ( 'yes I would like my hair to look like that !!...but it never did' ) they were very prone to bronzing, lots of airborne polutants present and frequently no glass ).

Cleaning products can also be very aggressive and easily become airborne, ask anyone who has used 'shake and vac' frankly I would rather smell what was there in the air before than that...

Finally, Frame varnish, coatings and backings including the 'cardboard back piece', many of these now come from China, and like many things that do some are very good products, some average and some poor, this reflects in the quality of the materials used.

Regardless of that, it is actually pretty rare, mis fixed or mis washed prints tend to stain rather than bronze, in saying that they can, and in answer to one reply yes toning will also help insure against bronzing on RC or on FB.

Simon ILFORD Photo / HARMAN technology Limited :

BetterSense said:

For what it's worth I have had silvering-out-type degradation on EDU.Ultra paper processed about 4-5 years ago. I'm not positive it's the paper at fault, but it's something to think about.

Click to expand...

+1. Same here, EDU.Ultra had some deterioration after 1 year stored in office environment. Proper processing, two bath fixing 1+4, slightly overwashed (I tend to leave my RC prints in washer for much longer than recommended), but no toning. I suspect this paper is rather susceptible to environmental pollutants - it must be toned to completion to be fully archival. Another print done on Ilford paper at the same time with same chemicals and stored right next to Arista print kept just fine.

I actually had a few classes to create this effect with the chromoskedasic sabatier process. I brought and used the freestyle Activator and stabilizer 2 part set. It was pretty fun to use, just dilute and paint on in full light after initial exposure and pulling from dev. We did it with fine paint brushes as well as making a mix of developer+a+b and pouring it over the print in a tray. When I looked into it, the literature pointed out that the sim wrong effect has to do with the silver in the emulsion clumping up into larger groups that once become large enough to reflect light in different wavelengths so you can see colors reflected back from different angles. It was a lot of fun and created really beautiful prints that you really need to see in person to get the full effect.

Do you have any prints that were not framed from the same session, my money is on there being no issue with the prints that were not framed.

RC prints in frames were an issue when I first started my business. I have never made RC prints for clients for this reason.My first business partner preferred RC over Fibre printing and when he left the company I had a bunch to redo because of this problem.

Ctein has written a long and definitive article on this subject. You may want to read it over as he shows that it can be due to over washing.

Take a look. Good reading.

PE