[Alt-photo] Sodium Thiocyanate For Fixing Out Lumens

Ryuji Suzuki rs at silvergrain.org
Fri Aug 18 03:55:14 UTC 2017

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 myself).

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
"I always tell my college students that two thirds of you will be more 
boring at age 30 than you are now." (David Brooks)

On 17 Aug 2017, at 21:25, `Richard Knoppow via Alt-photo-process-list 

>    I have also asked for the papers.
>    The T.H.James paper as far as I remember, is the one where he shows 
> that a small residue of thiosulfate in a processed emulsion protects 
> the image silver from oxidation.  This was such heresy when he 
> discovered it that he didn't publish anything until similar results 
> were reported by Fuji's lab. This completely changed the 
> recommendations for archival processing. It turned out that if an 
> emulsion was completely free of thiosulfate it would become oxidized 
> rather rapidly from peroxides in the air. So, the heroic treatment of 
> emulsions with hypo removers and long washes turned out to be counter 
> productive. Kodak was aware of this when they wrote the instructions 
> for Kodak Hypo Clearing Agent and limited both the treatment time and 
> subsequent washing time to account for it. The old Kodak Hypo 
> Eliminator was now strongly recommended against since it also did some 
> other damage to the emulsion and, in any case, had no effect on 
> residual silver complexes from incomplete fixing.
>     The protection from residual thiosulfate is not complete. Better 
> protection is offered by toning with either a sulfiding toner or a 
> selenium toner but partial toning with selenium doesn't work well. 
> Later research done by IPI shows that the best toner for image 
> permanence is obtained from a polysulfide toner since it tones all 
> densities equally.
> On 8/17/2017 5:37 PM, Jacques Kevers via Alt-photo-process-list wrote:
>> Marek & all,
>> I have these 2 copies. The xeroxes are quite bad, however. I just 
>> improved
>> the first in a quite decent pdf. Second will follow, but I need some 
>> time.
>> Whoever is interested, pls drop me a note at jacqueskv at gmail.com
>> Best,
>> Jacques
>> Jacques Kevers
>> Beau Site
>> Première Avenue 7
>> B-1330 Rixensart
>> Belgium
>> +32 2 653 56 02
> -- 
> Richard Knoppow
> dickburk at ix.netcom.com
> _______________________________________________
> Alt-photo-process-list | altphotolist.org

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