[alt-photo] Re: HYDROSCOPIC!

[Paul Viapiano]

I've used Sistan when I was satisfied with a print's color and didn't want 
to tone it. I haven't noticed any staining or other problems thus far.

Are there alternatives, especially for something like lith prints, that you 
don't want to tone?




----- Original Message ----- 
From: "Richard Knoppow" <dickburk at ix.netcom.com>
To: "The alternative photographic processes mailing list" 
<alt-photo-process-list at lists.altphotolist.org>
Sent: Monday, May 10, 2010 11:04 PM
Subject: [alt-photo] Re: HYDROSCOPIC!


>
> ----- Original Message ----- 
> From: "Marek Matusz" <marekmatusz at hotmail.com>
> To: "alt photo" <alt-photo-process-list at lists.altphotolist.org>
> Sent: Monday, May 10, 2010 6:19 PM
> Subject: [alt-photo] Re: HYDROSCOPIC!
>
>
>>
>> Bob,
>>
>> My two cents from the chemistry perspective are similar to Ryuji's. 
>> Ammonium thiocyanate is a complexing agent for gold. It is a common 
>> problem for gold toners to keep gold in solution for prolonged periods of 
>> time. ANd while the thiocyanate bases toners are faily stable, they will 
>> eventually plate the gold in the bottle loosing their potency. They are 
>> best used just after the addition of gold. Get a batch of prints and tone 
>> them all at one session. I kept a bottle of a thiocyanate toner for yers 
>> and it had a lot of gold sediment in it.
>>
>> You can just add more gold to replenish the toner, as all other reagents 
>> are in large acess.
>>
>> It really matters little if you add 25 or 50 grams of solid ammonium 
>> thiocyanate(I actually have not tried that, so final judgement is in the 
>> experiment), but have used thicyanate gold toners exstensively in my 
>> silver B&W past. Interestingly enough just before final collapse of B&W 
>> chemistry Agfa introduced a silver image stabilizer that was thiocyanate 
>> based, but I did not really follow that and I think Agfa dropped their 
>> silver B&W chemistry. So perhaps both components can act to stabilize 
>> silver image, but gold will also change the colour
>>
>> The toner might be sensitive to the presence of fixers, so an extensive 
>> wash might be necessary to prolong its life, maybe somebody else might 
>> comment. But if you are using it in a batch mode, that is add gold and 
>> tone a bunch of prints at one time it might not matter a lot. Let us know 
>> in any event.
>>
>> Marek
>     I believe you are thinking of AGFA Sistan, it was actually on the 
> market for a number of years. I don't have a bottle handy but I think it 
> contained Potassium thiocyanate and a wetting agent. AGFA changed their 
> recommendations for its use a couple of time. Too much could result in 
> staining. I was never able to find anything in the scienfific literature 
> proving its effectiveness. Fuji also sold a non-toning stabilizer but I 
> don't know what was in it and it was, AFAIK, sold only in Japan. Ryuji may 
> know more about both of these.
>
> --
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk at ix.netcom.com
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