Two bath sepia toning "experiment"

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Marco B

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Hi all,

I have been using a two bath bleach-redevelop sepia toner for quite a while now with success. It is a ferricyanide bleach / thiourea combo. Now I always assumed that the bleaching step was a vital step in doing sepia toning with thiourea, although I am aware that there are direct single bath sepia toners as well (polysulfide, for the difference, see here: http://81.207.88.128/science/photo/toners/sulfide.html).

I assumed thiourea by itself would not be capable (or hardly at least), of toning a print. But here's what I observed recently:

I had a series of 4 photos I needed to tone. I toned the first two, but, contrary to my normal practice of rinsing the prints after the second thiourea bath in plain water, I was a bit lazy and decided to drop them back straight into the tray having the 2 remaining prints to be toned.

When I took out the third print to be toned, and put it in the ferricyanide bleach, I noticed that contrary to expectations, the bleach did not seem to attack and work immediately on the highlights, as it normally would. I was a bit stunned. The print seemed to resist the bleach. When I left it in there longer, I noticed that the process of bleaching started, but seemed mainly concentrated on midtones and shadows. When I quit the bleaching and rinsed it, I was surprised to see that actually, the highlights were almost not bleached, while normally, they would be the first to be bleached. Midtones and shadows were.

I than realized, that, contrary to my expectations and thoughts, the two already toned images, and the carry over of thiourea solution, must have sepia toned the highlights (zone 7 up to maybe beginning or half zone 6)...

This was a big surprise, not only because of the direct toning action, but also because of the very low concentration of the thiourea toner already capable of doing this. I always wait quite long to have the solution run of the prints before moving them to the next tray, the same here, meaning the amount of carry over of thiourea solution must have been low, and diluted in almost 6 liters of water (I printed 16x20 inch). And that still managed to sulphide / tone almost the entire zone 7 of the print... I did not see a noticeable difference in tone by the way, meaning that it was not a full toning, but still.

Please note that I always rinse well inbetween the bleaching and thiourea toning bath, so I am pretty sure the amount of bleach possibly active in the thiourea bath, must be absolutely minimal (if bleach even survives the thiourea bath), so it seems a direct toning effect of the thiourea.

I also noticed a difference in the final color of the image. I prefer to only partially bleach back my images, as I like the deeper still black shadows caused by that. While sepia toning using a partial bleach / redevelop step can lead to a kind of split tone (highlights zone 7 sepia, midtones and shadows almost neutral), the pre-toned prints had a more "overall", equalized toning appearance (even though still not fully toned). The tone was actually very pleasing and slightly more dark reddish, instead of more orange / brown with the normally toned first two prints.

Now this raises a few questions:

- Is the bleaching step really necessary with thiourea toning ? (I am assuming a thiourea bath with sodiumhydroxide accelerator, as toning with just thiourea is also possible, but slower). I guess it is still a matter of speed, with pre-bleaching allowing maybe far faster toning, but I am surprised by the speed with which the strongly diluted "carry-over" toner managed to tone the still untoned prints.

- Are there people who have done a direct single bath toning using thiourea alone, if at all practical?

- Are there people who actually have used this phenomenon as an "alternative" strategy for sepia toning, to achieve other tones?:

* drop print first in thiourea toner for a first small toning step
* rinse print
* drop in ferricyanide bleach
* rinse
* back into thiourea redeveloper

Marco
 

Ian Grant

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Sounds about right. Thiourea and Sulphides will attack an unbleached print, how quickly will depend on the emulsion. The degree of toning isn't as controlled as bleaching and is unlikely to affect the shadows as much.

Ian
 
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Marco B

Marco B

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Oh yes, one forgotten detail. The paper I used was Kentmere Finegrain Warmtone, which, like the other Kentmere papers I have used (Fineprint VC and Select VC), tones very nicely and bleaches easily in ferricyanide bleach, much like Ilford Multigrade Warmtone paper. The main difference of all these Kentmere papers with Ilford Multigrade Warmtone, is that the latter has an appreciably deeper maximum black.
 

dancqu

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Fixer As Well

Sounds about right. Thiourea and Sulphides
will attack an unbleached print, ... Ian

If the print be slightly acidified pre or post it's
short soak in fixer. Yet to be tried but I have
read of the method more than once.

Now that the subject has come up a test of
the method just went to the top of my
priority list. Nothing like sulfur for
longevity. Dan
 
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Marco B

Marco B

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If the print be slightly acidified pre or post it's
short soak in fixer. Yet to be tried but I have
read of the method more than once.

Dan, I have no idea what you mean with this sentence :confused:, could you please elaborate a bit?
 

dancqu

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Just adding fixer to Ian's list. Prior to or just
after a soak in fixer acidify the print. I've read
of vinegar being used with good results. Dan
 
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Marco B

Marco B

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Just adding fixer to Ian's list. Prior to or just
after a soak in fixer acidify the print. I've read
of vinegar being used with good results. Dan

I still don't completely understand what you are after :confused: Do you mean that acidifying the print can be used as a means to create a different color / effect in the subsequent two bath thiourea toning after the fixing? So as a creative approach to a different sepia toning result?
 
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Marco B

Marco B

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Tim Rudman describes a similar process that he calls "presulphiding" on pages 23-24 of The Photographer's Toning Book. Although at first I thought it was limited to sulphide based toner, the text does state that thiocarbimide toner may also be used.

I don't have this book, probably should get it once. But you mean he states that the image is indeed first directly toned using thiourea (or alternatively in a polysulphide toner or so), only than to be bleached back in ferricyanide and toned a second time in thiourea, as I wrote in my first post?
 

dancqu

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Fixer As Toner

I still don't completely understand ...

Fixer in a practical way is a source of sulfur.
Hypo alum toners and Nelson's Gold toner are
foremost examples. Toning is sooner done
if the print is acidified.

Fixer is induced to relinquish it's sulfur if acidified.
Forget all that other stuff and just think vinegar
and fixer.

Of course we are speaking of ready to tone prints.
Like I said I've read of but not tried the method.
For starters I'd employ very dilute solutions
using sodium thiosulfate, and vinegar or
sodium bisulfate. Dan
 

dancqu

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Direct Sepia Toning Using Hypo and Vinegar

Search this forum for, donmck . The thread is
Toner Question. Don details the method. Dan
 
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Marco B

Marco B

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Fixer in a practical way is a source of sulfur.
Hypo alum toners and Nelson's Gold toner are
foremost examples. Toning is sooner done
if the print is acidified.

Fixer is induced to relinquish it's sulfur if acidified.
Forget all that other stuff and just think vinegar
and fixer.

Of course we are speaking of ready to tone prints.
Like I said I've read of but not tried the method.
For starters I'd employ very dilute solutions
using sodium thiosulfate, and vinegar or
sodium bisulfate. Dan

OK, thanks for explaining further Dan. As I understand you now, you are actually suggesting using fixer and an acid (vinegar), as an alternative sulphur toner... I guess this will require unused, fresh fixer, as you probably don't want the normal silverthiosulphate complexes of used fixer interfering, and therefore also done after the normal processing cycle and already fully fixed image?
 
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Marco B

Marco B

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By the way, as an experiment, I have now also attempted to directly "tone" a print using thiourea alone, so no pre-bleaching using ferricyanide. Well, after 5-10 minutes or so in the thiourea, there is no visible "toning" effect. I guess the thiourea, based on the other experience, is slowly doing its job, but it won't result in a perceptible color change in a short time. So if the goal is to have a (slight) toning color change as well, direct toning with thiourea is not the way to go, a pre-bleach is necessary.

I am wondering if this is what a supposed "archival" treatment like Sistan is based on, that is supposed to give some extra protection without changes in the appearance of the print?
 
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Marco B

Marco B

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Just looked up the MSDS (Materials Safety Datasheet) of Sistan, as I started wondering what it contains. Its main active ingredient seems to be PotassiumThiocyanate (K+SCN-)

http://www.freestylephoto.biz/pdf/msds/agfa/Agfa_Sistan.pdf

Wonder what reaction that performs on the silver :confused:, e.g. if it also somehow gives up its sulphur, acting as a mild sulphur based toner, or what it does else compared to thiourea - (NH2)2CS?

Some chemical info on thiourea:

http://www.answers.com/topic/thiourea

Hmmmm. Now found this page explaining a bit about Sistan. Definitely another kind of process (scroll down to section "Other Treatments"):

http://unblinkingeye.com/Articles/Archival/archival.html

The Thiocyanate is supposed to react with free Ag+ ions, not the silver itself, resulting in the formation and stabilisation of the colorless compound SilverThiocyanate Ag+SCN-. It is supposed to capture free Ag+ ions released by deterioration of the silver image. But that is something different from doing a sulphur based toning and bonding the silver to prevent deterioration to begin with!

Marco
 
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