----- Original Message ----- From: "Bogdan Karasek" <bkarasek@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, April 04, 2008 8:37 PM
Subject: [pure-silver] Re: Problems with KRST????
Hi,
Se below:
Richard Knoppow wrote:
----- 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.
The problem is that the solution itself turns brown and you can't see
anything, liquid fudge! Leaves a brown stain in the white tray.
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 use distilled water so the water should be free of all contaminants!!!
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.
I did wash the tray in household bleach between the first "liquid
fudge" and the second "liquid fudge" but I rinsed very well, I hope,
but then how to explain the first solution turning brown. No presence
of bleach.
Have you tested the toner with some other kind of paper?
Next move. I still have some Agfa Multi classic and will try toning
that with a fresh solution. Methinks that maybe there is something
with the paper, Kentmere, but it was washed in Hypo Clear for 5
minutes, 40 minute continuous wash.
Thanks for the input. I'll follow recommendations and try again this
week end with a diff paper. I'll post results.
Cheers,
Bogdan
A forty minute wash even without the wash aid should get rid of any
acid in the paper. It _could_ be something in the paper, trying other
paper is the only way to prove it. The cause of the sludge is beyond my
knowledge of chemistry.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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