"Stefan Patric" wrote in message
...
On Sun, 04 Apr 2010 03:29:41 -0700, sreenath wrote:
Hi,
I am using a rapid fixer sold in India be the name
"Agefix" The
instructions that come with the bottle just suggests a
dilution of 3-5
times for film.
I have been using the suggested dilution with no problem.
My question is the capacity of this diluted fixer. I kept
using the 1
liter for more than a year. Every time I do a film clip
test and observe
that film clears very quickly.
Is it possible for the fixer to clear the film clipping
but still be
unable to fix the film completely?
Are there any other tests for fixers?
Agefix is an Agfa product. With standard dilution, no
replenishment, 1
liter will fix 1 square meter of film before the fixer is
exhausted.
That's about 20 rolls of 36 exposure, 35mm film.
Here's a link to the Agfa film chemistry pdf. The Agefix
info is on page
12 of the document.
http://www.cri.ensmp.fr/~silber/photo/docs/films.pdf
Stef
The real test for fixer is the residual silver in the
emulsion. There are two simple tests. One is about a 2%
solution of sodium sulfide (not sulfite) the other is a 1:9
dilution of Kodak Rapid Selenium Toner. Either will tone the
remaining halides or silver complexes readily leaving a
stain. A drop or two of the solution is placed on _wetted_
film or paper and left for a couple of minutes, they rinsed
off. It should leave NO stain if the emulsion has been
completely fixed.
With any fixer the capacity can be much extended by
using two successive baths. This technique extends the
ability of the fixer to completely fix from four to ten
times. Instructions for the technique and for the test
solutions can be found in the _Kodak Black and White
Darkroom Data Book_ I don't know if this is still published
but old editions have the same information in them.
The problem is that an exhausted fixing bath will
continue to clear emulsions long after it has become too
exhausted to completely fix out all the silver halide. The
complexes left in the emulsion will change over time to a
form which can no longer be removed by re-fixing and will
eventually destroy the image.
--
Richard Knoppow
Los Angeles, CA, USA