[pure-silver] Re: [pure-silver]Old & new KRST. Was Selenium followed by T-8 Polysulfide
- From: Ryuji Suzuki <rs@xxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Sat, 18 Dec 2004 15:37:59 -0500 (EST)
From: "Tim Rudman" <ps@xxxxxxxxxxxxxxx>
Subject: [pure-silver] [pure-silver]Old & new KRST. Was Selenium followed by
T-8 Polysulfide
Date: Sat, 18 Dec 2004 20:08:07 -0000
> Whilst it could be true, according to Doug Nishimura IPI
> were not able to demonstrate this as an explanation to account for their
> observations (there could be other explanations).
I agree, out of all existing reports that indicate some changes in
KRST during 1990s that I know of, none demonstrates what was changed.
But there are plenty of convincing data that KRST is less effective
than KBT or other sulfiding treatments. This is the source of
frustration because KRST is easy to use, makes nice rich black hue and
deepens blacks, while sulfiding provides stronger protection more
consistently across the board.
> [...] He went on to say 'that since we haven't found any solid
> evidence that there was indeed active sulfur in the old bottles of
> selenium toner our suggestion that sulfur might be involved is
> purely speculation.' This does not of course rule it out, - nor in.
Right, another hypothetical difference may be in the film/paper
emulsion part. Susceptibility to oxidative attacks varies with factors
like antifogging agent, not to mention halide composition, size and
morphology of the developed grains, etc. Another hypothetical
difference may be that storage condition, oxidative pollutants, and
all other storage-related conditions changed from 1970's to 1990's.
But there are a few anecdotal reports that are inconsistent with this
hypothesis. While there are a few viable hypotheses remaining, I don't
think determining what happened to a proprietary product in the past
is the most important part.
Please note that I'm not trying to identify the change in KRST or
criticizing Kodak for doing something in this area. I'm merely trying
to incorporate recent findings in a meaningful way to my darkroom
practice and sharing it with others. Somewhere along the way I noted
that mixing of KRST and KBT that worked with old KRST does not work
with new bottle of KRST. I mixed new KRST with liver of sulfur from
non-Kodak source, but it resulted in the same problem. This is not a
systematic test and my experience remains merely anecdotal, but it is
consistent with the hypothesis that some change was made in KRST. It
by no means prove it nor did I state it that way.
--
Ryuji Suzuki
"Keep a good head and always carry a light camera."
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