FB print deterioration: what went wrong here?

[Umberto]

The way I interpret all this is that it's less about the fixing itself but more about the washing afterwards. When the silver concentration gets too high, the fixer doesn't get washed from the paper properly anymore. Film and RC paper are much less affected as they don't absorb as much fixer as FB paper. That's where the wash aid might come to the rescue and enable sufficient washing anyway for FB paper.

I don't think an extended wash can compensate an improper fixing.
If the silver concentration in fixer is too high, the paper retains silver compounds. These can't be washed away as ammonium thiosulfate.

 

[miha]

Ilford writes in the technical information sheet of Rapid fix (page 4):
"If a high level of image permanence is required for commercial use the silver concentration in the fixer should be kept below 2 g/l when fixing FB papers. This approximates to 40, 20.3 x 25.4 cm, (8 x 10 inch) FB prints. Above this level compounds may remain in the paper base after washing and over time possibly contribute to print staining."
and at the bottom of the same page;
"The level of silver in a film fixing bath can be allowed to rise to 8–10 g/l without serious effect."
"RC papers can be processed in fixers containing higher levels of silver, 4–6 g/l as the paper base is protected on both sides by an impervious polythene coating."

The way I interpret all this is that it's less about the fixing itself but more about the washing afterwards. When the silver concentration gets too high, the fixer doesn't get washed from the paper properly anymore. Film and RC paper are much less affected as they don't absorb as much fixer as FB paper. That's where the wash aid might come to the rescue and enable sufficient washing anyway for FB paper.

Personally I use a single Ilford Rapid fix bath at 1+4 strength, 1 min fixing time and replenish it with 0.5 l fresh 1+4 fix every 10 sheets of 11x14 inch FB paper. 10 x 11x14 inch = 1 m2. I use sodium sulphite wash aid. So far that's seems to work for me.

This is how I see it as well. Makes sens to me.

 

[RauschenOderKorn]

I think both your old and new workflow should both produce archival prints. At least if executed as you describe it, there are no obvious problems which would explain this degree of intense deterioration. So maybe the print itself is not the problem.

You say you had your print hanging on the wall for about a year and a half. Have you ruled out influences caused by this hanging on the wall? This relates to humidity, fumes, the archival qualities of the frame, materials (glue?) in contact with the back side of the print, etc?

Have you taken the print out of the frame, what does the back side look like? Is there anything unusual on the back side of the print or the frame?

 

[spijker]

I don't think an extended wash can compensate an improper fixing.
If the silver concentration in fixer is too high, the paper retains silver compounds. These can't be washed away as ammonium thiosulfate.

It seems that a too high silver concentration does not cause improper fixing. It causes improper washing.

 

[Doremus Scudder]

Ilford writes in the technical information sheet of Rapid fix (page 4):
"If a high level of image permanence is required for commercial use the silver concentration in the fixer should be kept below 2 g/l when fixing FB papers. This approximates to 40, 20.3 x 25.4 cm, (8 x 10 inch) FB prints. Above this level compounds may remain in the paper base after washing and over time possibly contribute to print staining."
and at the bottom of the same page;
"The level of silver in a film fixing bath can be allowed to rise to 8–10 g/l without serious effect."
"RC papers can be processed in fixers containing higher levels of silver, 4–6 g/l as the paper base is protected on both sides by an impervious polythene coating."

The way I interpret all this is that it's less about the fixing itself but more about the washing afterwards. When the silver concentration gets too high, the fixer doesn't get washed from the paper properly anymore. Film and RC paper are much less affected as they don't absorb as much fixer as FB paper. That's where the wash aid might come to the rescue and enable sufficient washing anyway for FB paper.

Personally I use a single Ilford Rapid fix bath at 1+4 strength, 1 min fixing time and replenish it with 0.5 l fresh 1+4 fix every 10 sheets of 11x14 inch FB paper. 10 x 11x14 inch = 1 m2. I use sodium sulphite wash aid. So far that's seems to work for me.

Spijker,

Keep reading after the first paragraph you quote. The next sentence is:
"For prints that need maximum stability for long term storage a the maximum silver level in the fixer should not rise above 0.5 g/l i.e.. approximately 10 20.3 x 25.4cm (8 x 10in) prints."

You have a point about washing being an important part of the equation. There may be "easily-washed-out" compounds made by complete fixation and "less-easy-to-wash-out" compounds that happen after a certain level of dissolved silver in the fixer is reached, which, however, may be coaxed to diffuse out into the wash water by the wash aid. I'd like to see some research/facts/information on this possibility. Anyone?

Replenished fixer regimes depend heavily on monitoring the silver content of the fixer. I don't know if that's practical for low-volume users like most of us. How do you monitor the silver content in your fix?

Best,

Doremus

 

[spijker]

Doremus, I don't monitor the silver content of the replenished fixer. But after a while I'll start with a complete fresh batch, usually after 4 or 5 replenishments. I've done the math and at that point, the theoretical silver concentration would be at 1.6..1.7 g/l. So there's still some margin wrt Ilford's "commercial limit" of 2g/l. Combined with the use of wash aid, I should get a sufficient stability of the prints. Time will tell but so far I haven't seen any issues with my prints.

 

[Umberto]

It seems that a too high silver concentration does not cause improper fixing. It causes improper washing.

Correct. This is because it's much more difficult to remove silver compounds than residuals of ammonium thiosulfate.

As Steve Anchell writes on "The Darkroom Cookbook": "Improper fixing is probably the major cause of stains in toned prints. An exhausted fixing bath contains insoluble silver compounds that will be retained by prints and cannot be completely removed by washing. When these residual silver compounds come into contact with a toner, they form a yellow stain that is especially noticeable in the highlights and borders."