sistan chemistry

[Jerry Cunningham]

Does anyone know the chemistry of Agfa Sistan for those of us that like to make homebrew? It seems unclear if Agfa will continue to make the product. I like it.
Jerry

[Graham Hughes]

I don't know Sistan's formulation, but it wasn't the only product of its type on the market. Fuji has a product called AgGuard which is similar in nature to Sistan, not that I've ever been able to find it for sale in the US.

[Oren Grad]

I've never seen AgGuard imported here. The Sistan ingredients are listed on the bottle - I'll check my stock next time I'm downstairs in the darkroom - though I don't think the specific proportions are provided.

In any case, I'm hoping that if Sistan is lost, it won't be difficult for another major vendor like Ilford or a boutique like Photographers' Formulary to step in with a replacement. The major challenge will probably be not the complexity of manufacture, but rather the fact that the product is much less well known and less widely used than is selenium toner, so demand may not be very high. I believe that much of the demand for Sistan has been for use with microfilm, too, and for all I know that demand may be disappearing as well.

I think it's very useful to have a product like Sistan that helps preserve the image silver without changing the image character, and without adding substantially to processing time. In addition to its use with FB paper, a quick dip in Sistan is very convenient for adding some protection to RC prints that I decide I want to keep around. Maybe we should have an informal campaign to get the word out about how useful these products are.

[Arne Croell]

From memory, Sistan contains potassium thiocyanate (KSCN) and a wetting agent. I don't know the concentrations or whether there are any other ingredients. The potassium thiocyanate (also called potassium rhodanide in older literature, or potassium sulfocyanate) supposedly forms a film of insoluble silver thiocyanate around the silver grain, thus protecting it from oxidants.

[Jerry Cunningham]

Thanks for the help.
Jerry

[Oren Grad]

Just heard from Ingolf Marzenski of A&O Imaging Solutions GmbH:

Dear Oren Grad,

Thank you for your inquiry and for your interest in our products.

We will continue the production of Agfa Sistan silver stabilizer.

If you have any further questions, please do not hesitate to contact us.