Advice needed with Iron blue toning procedure

[Photopathe]

I started direct blue toning and I have some issues and questions. I was able to find Tim Rudman's Toning Book and I also have been reading on the web so I did my homework before posting.
My main issue is with fixer. Tim Rudman advices to fix the print after tonging to avoid degradation of the image mid-term (am passing on the chemical process details here). My first attempt was a failure as I forgot not to use my usual fixer (neutral/alkaline TF-5). I then prepared some Kodak F-24 acid fixer following Steve Anchell's Cookbook. I was curious and tried the full strength fixer and it messed up the colours and tones. Then, as per the recommandations, I diluted it 1:10 with distilled water and fixed the toned print for 30 seconds. The fixing stage still messes up the tones and colours. Colours shift to a weird and unpleasant pale turquoise and the light tones are getting too clear. It looks a little like some mild Sabatier effect I think. I read an article were the author gave up on fixing after iron toning stating that he yet has to see any degradation (some tones turning brownish) from skipping the post-toning fix. If anyone could share experience and advices about this it would be greatly appreciated.
I am also unsure about some other elements of the process. I am using a slightly acidic stop bath right after toning (1L tap water + 10ml white vinegar). It this really useful if I am to wash in running tap water afterward? Isn't it more useful to just give a final dip in this acidic stop bath just before hanging to dry? Also, if I use a 0.2% borax or 0.2% bicarbonate bath to have the colours shift towards blue/navy-blue after the final wash is it ok to go straight to drying afterward? If I am to wash again after the alkaline bath (Borax/Bicarbonate) there is again a colour shift.
Thanks!

 

[nmp]

I don't know if you have looked at this reference - it talks about the issues you are having:

Blue Toning

:Niranjan

 

[koraks]

I read an article were the author gave up on fixing after iron toning stating that he yet has to see any degradation (some tones turning brownish) from skipping the post-toning fix. If anyone could share experience and advices about this it would be greatly appreciated.

I think I read the same, or at least I think this is also mentioned on the page @nmp referred to.

My experience is:
* I've also yet to see image degradation on iron blue toned prints that weren't fixed after toning.
* I've witnessed some odd interactions that indeed looked like a very strong sabattier effect on some test strips that were fixed, not really washed (perhaps briefly rinsed) and then iron toned. I found it an interesting effect, but it proved hard to replicate reliably. In any case, the combination of iron toning and ammonium thiosulfate fixer can do interesting things. If you're looking for straight blue toning, I'd say just don't fix afterwards.

I am using a slightly acidic stop bath right after toning (1L tap water + 10ml white vinegar). It this really useful if I am to wash in running tap water afterward?

Not necessarily. AFAIK there's a very dilute bleach (sodium carbonate or similar) suggested if you experience staining of the whites and/or paper base. Otherwise, the acid dip doesn't sound particularly necessary, unless you somehow experience issues with the image tone being too much shifted to magenta for your taste. The iron complexes in such prints tend to shift to magenta (and bleach out) with a high pH and shift more towards cyan (and remain stable) at a lower pH.

Also, if I use a 0.2% borax or 0.2% bicarbonate bath to have the colours shift towards blue/navy-blue after the final wash is it ok to go straight to drying afterward?

I see no particular harm in this as most papers are alkaline buffered anyway and appear to age just fine that way. In general I'd try to wash prints as well as you can, but with iron toning there are valid reasons to not do so, as the Prussian blue just isn't all that stable and even trace amounts of alkalinity in wash water can bleach them considerably.

From an archival viewpoint, I guess iron blue toning will always be a somewhat tricky proposition. On the other hand, cyanotypes from the 19th century overall seem to age pretty well.

 

[nmp]

So basically what is happening is the paper is left with silver ferrocyanide in addition to Prussian blue. When an alkaline fixer is used, it is bleaching the Prussian blue to ferric hydroxide, shifting the overall color. I wonder if thiosulfate is also doing something funky with Prussian blue (since it is a reducing agent as well.) That might explain the behavior in an acidic fixer.

Silver ferrocyanide may not be as UV sensitive as silver chloride or bromide, so it might take a long time before it gets fully reduced to metallic silver if not removed from the paper by fixing, particularly in absence of any developer to give a push. But then it may not be such a big problem since it will simply add to the density/intensity of the print, mostly. I have not done this on a straight silver gelatin but on POP - where I deliberately "developed" the silver ferrocynide (via bromide route) - it resulted in a darkened green print:

Additive Prussian Blue Toning of Silver based Prints

Earlier I outlined a process by which a silver based prins such as salt, POP, VDB, kallitypes etc including traditional silver gelatin can be toned in cyanotype like chemistry without losing the underlying silver image. https://www.photrio.com/forum/threads/van-dyke-over-cyanotype.177290/page-2...

www.photrio.com

In silver gelatin, perhaps the re-developed silver may not be so warm, in which case the blue color will simply darken if the residual silver ferrocynide gets converted to metallic silver.

:Niranjan.

 

[Photopathe]

Thanks for the help! It's been very useful. I'll stop worrying about not fixing after toning (with iron) and simplify my process, which is always a good thing when possible. I'll just wet the prints, tone, wash, and finish with an mild alkaline bath to shift the colour when needed. Next step I am giving a try with indirect blue toning and will apply the same principles.

 

[Photopathe]

Still I wonder if it would not help with image permanence to give a final acidic bath to the print after washing. After the running (slightly alkaline) tap water wash but before the quick dip in 0.2% bicarbonate. Since the image is supposed to fade away in an alkaline environment I would think that a final acidic bath would help with that and that the optional dip in highly diluted bicarbonate that comes after would not necessarily counteract the acidic bath.

 

[pentaxuser]

What might be interesting is whether iron blue toned prints last longer when done in acidic water as opposed to alkaline water. I have no knowledge of geology of Canada but here in the U.K. we have regions with alkaline water that will form serious limescale on kettle elements and water tap outlets over a matter of months and other areas where the water is acidic in comparison.

pentaxuser

 

[nmp]

I would think you would want to leave the print in a neutral or slightly alkaline state for longevity of the physical paper. If you follow your acidic treatment with a mild alkali, first it will neutralize the residual acid and only after that it will do its color thing (bleaching Prussian blue.) The fading of the blue (or browning) in an alkaline environment over time should be reversible by treatment with acidic potassium ferrOcyanide. Blue can also fade due to exposure to UV light when displayed (Prussian blue is converted to Prussian white.) That can also be reversed by storing in the dark (or treating with hydrogen peroxide.)

To simplify the process, I would envision washing after toning with neutral(ish) tap water followed by an acidic treatment (in case there is any yellow staining due to residual iron compounds.) Alternatively like what I do with cyanotypes, start with mild acid (I prefer citric) followed by tap water. Then if you want to shift the color, do an alkali treatment followed by a final wash. That's how I would approach it anyhow, if I were to make a blue-toned silver gelatin.

:Niranjan.

 

[koraks]

If you follow your acidic treatment with a mild alkali, first it will neutralize the residual acid and only after that it will do its color thing (bleaching Prussian blue.)

There's also the diffusion of both baths to take into account; perhaps you implied this as well?
The emulsion is on top and the Prussian blue seems to be very accessible indeed. You can probably get away with an alkaline wash that's so brief that it will touch the Prussian blue but won't significantly diffuse through the paper base. A preceding acidic wash would sill leave the actual paper base in an acidic state.

 

[nmp]

There's also the diffusion of both baths to take into account; perhaps you implied this as well?
The emulsion is on top and the Prussian blue seems to be very accessible indeed. You can probably get away with an alkaline wash that's so brief that it will touch the Prussian blue but won't significantly diffuse through the paper base. A preceding acidic wash would sill leave the actual paper base in an acidic state.

I actually was thinking about primarily the surface and sub-surface. For the bulk, it gets complicated - function of relative duration in each bath, their strengths, paper thickness etc. However, I am not sure I understand why one would want an acidic reservoir in the paper - as it will degrade the paper, perhaps faster than the blue can fade. On the other hand, if there is alkalinity in the paper, it might continue to bleach the blue (although reversibly.) So the compromise between the two devils is keeping it neutral by washing thoroughly with even a couple of dist. water rinses at the end for the keepers. That's what we do for cyanotypes and I can't think of any reason why this would be any different.

:Niranjan.

 

[Photopathe]

A little update here. I ended up completely skipping the final wash after toning with iron. I find that if I wash in either tap or distilled water after using an alkaline or acidic bath to get the tint I want (greenish to blue...) I will at least partly loose that tint. Reference authors such a Rudman and Moersch do mention that it is necessary procedure as they do for the acidic stop and fix but that's just not working for me. Here are some prints of pictures taken with my Nikonos III (Delta 3200 at 6400). I gave a final bath of 10ml vinegar in 1L tap water.