[Alt-photo] Sodium Thiocyanate For Fixing Out Lumens
rs at silvergrain.org
Fri Aug 18 04:38:17 UTC 2017
No worries, the world moved on, and I moved on, as far as professional
life goes. I spend much of my time as commercial and portrait
photographer and, guess what, I shoot digital for those, although I have
many of my silver prints on my studio walls, two Durst enlargers
standing here, and boxes of films and film a few film cameras on my
Agfa had a product called SISTAN, which was essentially a finishing
surfactant (wetting agent) with a very dilute thiocyanate mixed in.
There was a controversy as to what was the range of safe and effective
concentration, because above a certain level of thiocyanate
concentration, this agent was actually detrimental. Too weak, and it was
ineffective. AGFA itself revised their recommendation. Independent
research to replicate their claim was limited. That is what you
(Richard) was worried about back then.
Fujifilm had a product called Ag Guard. This product had an advantage
over SISTAN because there was no harm using too much or too strong of a
solution. But it wasn't sold outside Japan, and it also used an organic
compound that was not readily available. The compound is also not
exactly easy to synthesize (see the patents referenced from my paper).
Ag Guard was one product that would be not exactly impossible but
absolutely cost prohibitive if you tried to mix your own, even after the
I was looking for a compound that would be readily and inexpensively
available even after the silver halide imaging industry is completely
gone and still very effective for image protection. One of the anonymous
reviewers apparently didn't like this part and advocated to use Ag Guard
for image protection purposes, which made me guess that the editor sent
my manuscript to the guy who invented Ag Guard (but of course, there is
no way to confirm that). I think the other reviewer was a very well
informed professional conservator and s/he was very positive about my
One caution. Thiourea was mentioned as potentially useful image
protecting agent for many reasons in some places, but there was no
published work proving or clearly rejecting this. I tested it (not in
this paper), and I should say that this compound shouldn't be used as a
protecting agent for silver image. It slowly discolors silver image over
the course of a few years in normal storage conditions. Not exactly in
the context of protecting developed out silver image, but guess who knew
that many decades prior, and that was of course James.
"The essence of the beautiful is unity in variety." (Felix Mendelssohn)
On 18 Aug 2017, at 0:03, `Richard Knoppow wrote:
> I could not remember the name of AGFA Ag guard or would have
> mentioned it before. I am glad to see you researched it and found it
> effective since there was some doubt in popular literature. I must
> still have several bottles of it.
> I am sorry to hear that no one is interested in silver image
> protection any more. I am sure that is very discouraging.
> I am not sure of the title of James paper that I was thinking of,
> something very similar to the one mentioned.
> On 8/17/2017 8:55 PM, Ryuji Suzuki wrote:
>> I forgot to advertise my own work.
>> Fujifilm Ag Guard is effective in protecting silver image from
>> oxidative attacks (that is not my work, though I confirmed it
>> So is an alkaline solution of 2-mercaptobenzimidazole (formula in my
>> The actual paper in PDF (Japanese language only) is here:
>> I sent it to Doug Nishimura and Gawain Weaver and asked if it's worth
>> publishing in English. Some said no one was researching conservation
>> of silver imaging material (no more research funds).... don't bother.
>> Some also cautioned me that professional conservators are discouraged
>> from performing any process that chemically alters the image, silver
>> or otherwise. Although Ag Guard and 2-MBI do not alter the image
>> itself (that is the point of this approach, as opposed to toning),
>> and this point is explained in the paper, the distinction probably is
>> not very clear to average conservators. So, no, there is no English
>> version published anywhere. (Besides, this journal was one of the
>> very few last remaining journals that published new researches on
>> silver imaging... at that time back in 2010/2011.)
>> Ryuji Suzuki
> Richard Knoppow
> dickburk at ix.netcom.com
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