[pure-silver] Re: Ammonium Thiosulfate
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 18 May 2007 10:34:00 -0700
----- Original Message -----
From: "Lloyd Erlick" <lloyd@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, May 18, 2007 6:08 AM
Subject: [pure-silver] Re: Ammonium Thiosulfate
At 10:55 AM 5/12/2007 , Richard wrote:
...
If you use a non-acid fixing bath you must also use
a
plain water rinse rather than an acid stop bath. The rinse
should really be a short wash (perhaps 1 or 2 minutes) to
remove as much developer as quickly as possible.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
=====================
May 18, 2007, from Lloyd Erlick,
This is my method of processing all my film and FB prints.
I no longer use
acid of any sort in my darkroom.
The easy way to perform the short wash after the developer
is to fill the
tank or tray with plain tap water, agitate briefly, and
dump. I'm a bit of
a loon, I use a quadruple fill and dump.
My main reason for giving up acid stop and acid fixer is
that this is the
way to eliminate smells in the darkroom. Sodium sulfite, a
common
ingredient in developers, in combination with acid, such
as acetic acid,
releases sulfur dioxide. I know many people consider this
trivial, and I
used to just let it pass. But now I'm an old loon, and I
can't stand the
least whiff of ess ohh two. Hydrogen sulfide the same. One
whiff and all
activity stops until it's dealt with, terminated with
extreme prejudice.
If I decide to do some brown toning, with the good ol'
polysulfide toner,
which reeks of sulfur dioxide, I've learned I have to do
it outdoors. That
turns out to be a good thing, because it lets me see the
result of the
toning in daylight. The one time I did it indoors I
learned my lesson.
regards,
--le
I think there are two gasses involved here. Sulfur
dioxide has a "sharp" odor and is released when sulfite
reacts with acid. It is an intensly irritating gas and can
set off athsmatic reactions in a lot of people. Polysulfide
and other sulfide toners release Hydrogen Sulfide gas, this
is the stuff with the rotten-egg odor. It is also intensly
irritating if there is much of it and quite toxic. Toning
should be done where there is plentiful ventillation or
outdoors. Hydrogen Sulfide can also fog unprocessed
photographic materials, another reason not to tone in the
darkroom. Fixing baths do not emmit Hydrogen Sulfide unless
they are so old that they are decomposing. Eliminating
Sulfur Dioxide is a valid reason for avoiding acid in
processing, I certainly do not consider it trivial.
BTW, the well known but not much used Hypo-Alum-Sepia
toner was orginally made out of exhausted fixing baths. This
may actually be a practical use for exhausted baths because
they are saturated with silver. Usually some Silver Nitrate
must be added to a freshly made up Hypo-Alum toner to
prevent it from bleaching the image.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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