[pure-silver] Re: KRST
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sat, 18 Aug 2007 13:13:11 -0700
----- Original Message -----
From: "Adrienne Moumin" <photowonder2010@xxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Saturday, August 18, 2007 9:23 AM
Subject: [pure-silver] Re: KRST
Wow, thanks for that elaboration & those citations,
Richard. As always, I appreciate your time &
thoroughness!
In trying to get a handle on all of this, and break it
down to the simplest terms so I can remember it well
enough to put it into practice, I looked back into my own
personal archives of pure-silver posts on this topic. I
think I found one which condenses it, in this excerpt from
an 11/03 post (AFA I can tell) by Russ Gorman:
This looks like a quote of something I posted in the
past although it may be a paraphrase.
The information about using KRST at not greater than 1:9
and for not less than 3 minutes came from Dr. Douglas
Nishimura, of IPI, in a private conversation although I
think he posted it to the rec.photo.darkroom Usenet group
and maybe even to this list.
Unfortunately, none of the toners currently considered
to provide full image protection will do so without causing
some change to the appearance of the image.
Stabilizer treatments like Sistan or Ag-Guard do not
seem to be as effective as a toner although they may be
useful where a print must be displayed and no change in
appearance is desired.
Evidently, IPI did some preliminary testing on Sistan
which did not turn out well. Dr. Nishimura mentioned this to
me but later said the person who did the testing had made
some error in method. I think this had to do with leaving
too much of he stuff in the emulsion. Sistan will cause
staining unless the amount is right. The problem is that
Agfa changed their recommendations a couple of times. If
there is not enough Sistan in the emulsion the protection is
limited, if too much the Sistan itself causes problems.
Probably the safest treatment is either a Liver of
Sulfur toner or strong KRST. Combination toners like the
original Viradon or Kodak Polytoner also apper to provide
complete protection but both are discontinued. I have a
formula for a combination toner, published long ago by
Kodak, which works. It has no advantage over standard toners
as far as protection but can produce a modified color. I've
posted the formula to this list in the past.
Liver of Sulfur toners have the peculiar property of
toning faster when diluted or when partially exhausted. This
same property also causes them to continue toning in the
wash until most of the toner is washed out. If very dilute
or quite exhausted the toner can generate a peach colored
stain which is difficult to remove. So, KBT should not be
diluted further than indicated in its instructions.
The continued toning can be stopped by treating the
material in a 10% solution of Sodium Sulfite before washing.
Actually, I've found that plain Kodak Hypo Clearing Agent at
normal working strength works fine. This also immediatelly
clears the yellow stain left by the toner.
KBT is normally used at an elevated temperature because
it tones very slowly. However, it works at room temperature
and this may be advantageous when partially toning.
My combination toner, for some reason, works very
quickly, three minutes for full toning of prints. It also
must have the sulfite treatment as a sort of toning stop
bath and stain clearing.
Ryuji Suzuki wrote me that he had staining problems with
this toner but I tested using both old and new stocks of KBT
and KRST and could not duplicate the problem.
Copper and Iron toners, and probably other metal
substitution toners like Uranium, result in images which are
MORE vulnerable to atmospheric polutants than untreated
silver and should be avoided where permanent images are
desired.
Where a blue color is desired Gold toner will produce a
very permanent blue image on warm tone paper although not as
vivid as Iron toner.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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