[pure-silver] Re: Agfa Sistan

From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
Subject: [pure-silver] Agfa Sistan
Date: Fri, 27 May 2005 17:00:04 -0700

> The problem with Kodak 
> Selenium toner was that, in the low concentration used for 
> microfilm, it did not tone low densities enough leaving them 
> subject to oxidation. Actually, KRST will protect film or 
> paper fully if toning is carried out far enough. Far enough 
> will cause some change in image color and/or density in most 
> materials. Dr. Nishimura stated to me that 3 minutes in a 
> 1:9 solution of KRST will provide adequate protection.

I have said this repeatedly here and ohter places that KRST 1+9 for 3
minutes may not be adequate. There is a pretty thorough Danish study
showing that low density areas are converted to much lesser degree and
KRST toned specimens are not as durable as KBT treated specimens.  I
already posted references to that paper a few times.

Pictorial negative films are much less susceptible to environmental
pollutants, especially when they are kept in Print File or similar
plastic filing pages. So I generally believe that treatment like
Sistan or Fuji Ag Guard is adequate, provided storage condition is
reasonably good.

--
Ryuji Suzuki
"Keep a good head and always carry a light camera."
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