[pure-silver] Re: Mystery Hypo Test
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Tue, 24 Nov 2009 16:13:38 -0800
----- Original Message -----
From: "Ralph W. Lambrecht" <info@xxxxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, November 24, 2009 3:50 PM
Subject: [pure-silver] Re: Mystery Hypo Test
Richard
Thanks a lot. This is all good information. However, you
are making a
lot of references to paper processing again. That's not my
concern.
Can we limit this conversation to film please?
Nevertheless, the first part was VERY interesting, but I
don't think
it applies either.
Here is why:
1. I am using an acid fixer.
2. I am not using a hardener.
3. I am using HCA prior to the fix.
Given that, the diffusion theory seems to work, and in my
opinion,
HT-1 is a very good test, despite its reputation, if
properly applied.
My comparison to methelen-blue test verifies that. I just
like a bit
more sensitivity, which I was hoping to get from the other
formula.
Do think its worth a try?
Of course its worth a try. I would just not rely on it
for routine use until you have proven to yourself that its
reliable.
I was answering your questions sort of generically. Film
and RC paper fixing is much simpler than fiber paper since
one does not have to be concerned with the absorption of
fixer and complexes by the support or the sizing (baryta).
Film takes longer to fix and wash than RC paper because the
emulsions are thicker and because of the nature of the
silver compounds used (lots of silver iodide).
A comparison of fixing and washing times is interesting.
RC paper, fixing, about 4 minutes in sodium thiosulfate
fixer. 4 minutes wash with no wash aid treatment. The
treatment is not recommended.
Film, about 10 minutes in sodium fixer, some films may take
longer. Wash 30 minutes for untreated film and about 4 to 5
minutes for treated film
Fiber based paper fix may take as long as ten minutes in
sodium fixer. Dave Valvo, formerly of Kodak states the
longer time required in comparison is due to the absorption
of some silver halide by the baryta layer. Wash time for
untreated paper is one hour for single weight and two hours
for double weight. This is reduced to about 1/3rd the time
when a wash aid is used, i.e., about twenty minutes for
single weight and about 40 minutes for double weight.
The fixing time ratios are about the same when ammonium
thiosulfate (rapid) fixer is used but with film strength
fixer are less than half the time indicated for sodium
fixer.
Note that the very long fixing times (15 to 20 minutes)
found in some older books was more to allow the hardener to
work than the fixer.
Another thought (I am doing the same thing again) when
partially exausted fixer is used some of the reaction
products are not made completely soluble so they stay in the
emulsion. I rather think the permanganate test may miss
these.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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