[pure-silver] Re: Problems with KRST????

  • From: Richard Knoppow <dickburk@xxxxxxxxxxxxx>
  • To: pure-silver@xxxxxxxxxxxxx
  • Date: Sun, 6 Apr 2008 23:44:59 -0700 (GMT-07:00)

-----Original Message-----
>From: Stane Kocar <stane.kocar@xxxxxxxx>
>Sent: Apr 6, 2008 11:09 PM
>To: pure-silver@xxxxxxxxxxxxx
>Subject: [pure-silver] Re: Problems with KRST????
>A few years ago I try to tone some VanDyke Brown prints with very diluted 
>KRST before fixing and the result was similar you describe. Toner went black 
>and print gets brown color.
>Maybe your photos are not fixed OK.
>Regards from Slovenia
>Stane Kocar
    I wonder what is in van Dyke Brown that could discolor the toner. KRST is 
suggested by Kodak as an alternative to sodium sulfide as a test solution for 
residual silver, that is, as a completeness of fixing test. KRST is diluted 1:9 
for this purpose. Its advantage over the sulfide test is long life for the 
working solution and lack of the rotten egg odor. However, it fails to stain if 
there is a lot of hypo in the emulsion. 
    I can understand KRST leaving an overall stain on improperly fixed prints 
but the change in the solution itself is a puzzle. I don't remember exactly how 
van Dyke Brown works but I believe it is an iron process similar to blue-print. 

Richard Knoppow
Los Angeles, CA, USA
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