sulfiding treatment and testing methods (was Re: Does anyone know this person or the work)

From: Jean-Paul Gandolfo <jpgalt@infonie.fr>
Subject: Re: Does anyone know this person or the work (late)
Date: Fri, 17 Sep 2004 12:28:31 +0800

> The scope of the study wasn't to compare dichromate and farmer used
> as reducers. We were aware of the problematics associated with
> dichromate and we make the choice of Farmer as an alternative
> answer. The conversion ratio in high densities ranged from 18 to 29%
> with our method. Indeed, theses mesures as lower, compared with the
> results you can get with dichromate but the stain is out, the ISO
> recommendation too...

That is understood, and one issue with ferricyanide bleach is that its
oxidative power fluctuates unless its action is "buffered" with
ferrocyanide. (Its oxidative power is very strong at the beginning of
bleaching and it gradually weakens.) So I wish there were a standard
stabilized ferrocyanide bleach for this testing purpose with its
testing results compared to peroxide fuming tests... It's easy for me
to do the bleach part but I'm not set up to do the fuming tests...

By the way, how many seconds do you treat your prints in your dilute
SilverLock solution at what temperature?

> The polysulfide treatments were applied with low dilution (10, 25,
> 50). I don't see the paper tests but I guess the hue was probably
> very warm.

I've used comparable concentrations with a few of my favorite papers
developed in phenidone-ascorbate neutral tone developer of pH 10.3.
(Note however that my toning solution contains both polysulfide and
selenium like Kodak POLY toner and AGFA Viradon before they
changed... these are not used for microfilm but I like them for
prints.) Papers like Agfa MCC and MCP gives very slight hue shift in
30 seconds in 1:20 strength, but bleaching test indicates that the
treatment is effective. Longer toning with these papers will give
black brown or purplish brown hue, which is of course more resistant
to oxidation. On the other hand, Forte Fortezo paper gives visible
warming even in a 15 second treatment, and the hue continues to shift
to orange brown. All these toning is at room temperature (25C).

> > Another interesting study I found is by a Konica group of Chika
> > Honda. They were concerned about permanence of medical radiographic
> > films, and they found peroxide fuming test to be too powerful for
> > predicting image degradation in relatively short useful life of
> > medical records (a few years) stored in office environment.

> If you have the quote, I am interested in getting it.

The abstract is:
http://www.imaging.org/store/epub.cfm?abstrid=1971
There was a full paper published in the journal, which I can send you
when I'm back in office.

The abstract very briefly mentions the positive effect of PMT, but the
full paper omits that part altogether. So I contacted Chika Honda and
asked for a bit more details. He did not publish the results for that
part in any language, but maintained that his results were positive
about PMT's image protecting effect when added to the developer bath.

I have personal experience with Sistan, but all I have is anecdotal
reports when it comes to its efficacy. Another compound of interest is
2-(amidinothio)ethanosulfonic acid, which is the active ingredient of
Fuji Ag Guard. I bet these treatments with soluble compounds will be
harder to assess for their efficacy correctly using bleach tests, and
fuming tests are called for.

> Agfa people are very nervous about the topic

I've heard of rumors that they aren't very enthusiastic about testing
efficacy of Sistan but I wonder why.

> the bad weather blowing on BW silver market will be not able to help
> me ...

It's very hard time but I hope people from industry become more open
about sharing their knowledge with scientists and "no one" like me, as
the financial motivation of starting up a new business is pretty low.

--
Ryuji Suzuki
"You have to realize that junk is not the problem in and of itself.
Junk is the symptom, not the problem."
(Bob Dylan 1971; source: No Direction Home by Robert Shelton)