[pure-silver] Re: Problems with KRST????
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 4 Apr 2008 20:11:35 -0700
----- Original Message -----
From: "Bogdan Karasek" <bkarasek@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, April 04, 2008 6:32 PM
Subject: [pure-silver] Problems with KRST????
Hi again,
I've run into some unexpected problems toning with KRST.
I've been doing some tests and comparisons and wanted to
check out the Kentmere papers. I got what we had in
Montreal, "finegrain" and "warmtone", both semimatte VC
papers in 8x10 size. I wanted to compare it's toning
properties with Agfa MultiClassic. I had a half full
bottle of KRST which has been on the shelf for close to a
year. I diluted the selenium 1:9 in distilled water as is
my habit. By the time I had the second sheet of Kentmere
in the toner, the toner started turning brown and by the
fifth sheet, the toner looked like liquid fudge;
impossible to see the image in the tray.
I had done the prerequisite washing, 5 min in Hypo Clear,
then a 40 min wash in running water, the selenium was
mixed with distilled water, no other additives. I went to
the photo store today to get a fresh bottle of KRST and
asked the clerk about the phenomenon of the selenium going
brown. he told me that if it had been sitting on the
shelf for close to a year, half full, then it went bad.
Is this a reasonable explanation, that the toner went bad,
oxidation because only half full????
With the fresh bottle of KRST and using some left over
prints from yesterday, I proceeded to tone them, same
protocol as before. By the second sheet, the selenium
started getting a brown hue to it. I find this week's
experience with KRST rather odd because I have never had
it go brown on me, not especially with a fresh bottle of
KRST.
I'm trying to figure out what went wrong and nothing comes
up.
Several questions: what is the shelf life of KRST? ... I
checked the Kodak web site but no information on that
score.
Is the Selenium dilution supposed to change color after
only several sheets have been toned in it??? And turning
brown???
If anybody has any ideas, comments, questions or other
observations, they are welcome. I sort of miffed and
puzzled by this experience and would like to get to the
bottom of it.
Cheers,
bogdan
I've not had this particular problem. The main source of
staining with KRST is acid in the emulsion. This can cause a
deposit of precipitated elemental selenium all over the
emulsion. A mild alkaline bath before toning will prevent
this. Unless your water is very acid the treatment in KHCA
before washing should also prevent it.
I would be concerned with residue of something in the
tray.
The only thing I've observed with old KRST is that some
elemental selenium will precipitate in the form of fine
black flakes. AFAIK, these do no harm although they probably
reduce the capacity of the toner a bit. I just filter the
stuff out.
Have you tested the toner with some other kind of paper?
Not the colored stuff but fresh from the same concentrate?
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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