Just to confuse things further: the stains I had were only silvery rather than having any blue sheen and, if not too extensive, could sometimes be "rubbed out" with a gloved finger in the toner. It only happened a few times so I never really tried to investigate.
I suspect we had different events (though they might be chemically related) - unfortunately I lack the chemistry to be of any use in considering possible causes...
Bob: I agree with you that the stains are far more silvery than "bleu-ish", so I do think we witnessed the same effect. And I also confirmed your "rubbing out" effect (in my case by agitating the tray a little bit more). The stains are however, only removable, when still in aqueous environment of the initial toning...
Originally Posted by Bob F.
My chemistry is from my high school days and a university biology study. Gets me there in understanding the basics, but I'm not an expert either...
Tim: I have requested the data sheet from the manufacturer, as you suggested. Let's see what they come up with... If there is any useful information about the chemical composition, I'll post it here.
Hi Tim (and Bob and others),
Sorry for the delay in responding. Hope you still have this thread in your "watch" list.
I have now received the datasheet from the manufacturer. Not much surprises though, it's indeed a thiourea based toner, with the following composition:
- Potassiumbromide 5-20%
- Potassiumferricyanide 5-20%
- Thiourea <1%
- Sodiumhydroxide 2-5%
- Potassiumcarbonate 5-20%
- Potassiumbromide 1-5%
According to the manufacturers instruction manual for the toner, this stock solution (the toner comes as a liquid!) needs to be diluted 1:9 to get at the working solution strength.
The only things that slightly puzzle me are the very low thiourea contents, and potassiumbromide in the toning bath. Thiourea being the active compound for donating the sulphide anions, I would have expected some higher content. But maybe my feeling as to the contents of silver in a print is simply completely wrong, and only little thiourea is needed to convert that silver... Well, the toning bath works well anyway when not exhausted
I wonder what the function of the potassiumbromide in the toning bath is. I have seen some recipes for thiorurea baths once on a webpage, and none had potassiumbromide in the toning bath...?
Lastly, I recently visited a museum exposition that included some beginning of the 20th century pictures (1900-1920). Some of them showed a similar "metallic" sheen in the darkest parts of the images (which I presume were also sepia toned judging the color). The stains really looked VERY MUCH like my stains on my dried prints...
I now begin to wonder, having read the book by William E. Leyshon that I recently posted about on this thread:
if the metallic sheen on my prints is actually simply a "tarnishing" layer?? Maybe that the exhausted toning bath, that maybe includes harmful reaction products as well, can cause a rapidly accelerated "tarnishing" process on prints
Well, it's another wild theory, hope you can shed some light on this... I also intend to do some more research / reading on tarnishing anyway, since I'm interested in the details behind toning and archivability of photos.
I've also experience a similar shiny metallic-like deposit from a homemade ferri/bromide and thiocarbamide/sodium hydroxide bleach and toner combo. The only pic out of the whole batch of toned prints that displayed the shiny bits was the Kentmere Fineprint VC fiber. Trouble is, I can't tell you whether it was one of the first bunch or the last that went into the toner in order to rule out toner exhaustion.
Someone (Dave maybe?) mentioned fixing after this sort of toning...what were the results? Did fixing remove the metallic sheen? My notes say only to wash and re-fix if the full density of the print doesn't return after toning. I'm going to try and post my example.
I've actually had that result on 'normal' prints a few times - though it was VERY long ago and I hadn't had it since. I imagined to myself it was due to hard local water... but I'm not so sure about that at the moment now. Indeed it resembles what is called 'silvering' on vintage silver gelatin prints - I could easily imagine it is the very same process which has been elicited chemically by some impurity, mishandling or other... perhaps something in the air...?
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Here's my shiny example....
Marco - Are you applying the liquid emulsion onto paper? It might be possible that you are not washing the fixer completely out of the paper, allowing the fixer to interact with the toner, causing the staining you're seeing. The hypo might be more difficult to wash out of the paper your using compared to regular fiber based photographic paper, and require longer washing times. And there might also be some chemicals in the paper itself that are interacting with the liquid emulsion and toner. Just a thought.
At the time, when AGFA still existed, I had the same problem on MCC111FB.
Thus I asked AGFA for advice, and they told me to soak the print in a fresh 1 % glacial acid bath for about 1 min. and wash the print afterwards as usual for FB paper, the stains were gone!
They never told me what caused it, so, when ever I have a problem after toning, the 1 % glacial-acid is near.
The same for the problem of that chalky feeling FB paper sometimes can have after multiple (split) toning.
I do not know if this will work for you, but it would not harm to give it a try, I hope so.
"...If you can not stand the rustle of the leafs, then do not go in to the woods..."
(freely translated quote by Guido Gezelle)
PS: English is only my third language, please do forgive me my sloppy grammar...
Hi Kathy and others,
Thanks for posting your example of the metallic sheen. Yes, it does very much look like my stains. Also clearly noticeable is the preference for the dark parts of the image. This example also very much resembles what I saw on these beginning of the 20th century pictures.
Phillipe: are you sure your stains were clearly "metallic"?? As Tim wrote:
"Thiourea sepia often leaves a white deposit which dissolved in 3% acetic acid or simply some dilute stop bath, but it doesn't look metallic (to my eye)."
I've had these "white deposit" stains sometime as well, it's most likely simple calciumcarbonate / calcareous deposit caused by non-demineralized water, as indeed they are removable with acetic or glacial acid, as I could confirm Tim's recommendation. However, these stains, although they somewhat look like the "metallic" stains, are not as metallic, nor are they exclusively limited to the darker parts of the image. So I think this is another issue...
I intend to get the book "Care and identification of 19th century photographic prints" by James M. Reilly. According to Leyshon, there should be a chapter describing the processes underlying "tarnishing" in that book.
I already know I can get it in the Amsterdam library, but it needs to be specially ordered, as it is in the storehouse of the library... may take some time.