[pure-silver] Re: High B+F with DS-10
- From: "John Black" <jblack@xxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 3 Feb 2005 18:05:00 -0500
>
> > Fresh, relatively high sulfite fixer and the use of a hypo clear will
reduce
> > fog some too.
>
> What's your definition of fog?
>
For photographic purposes, my definition of fog is a bit broader than just
the conversion of non-light exposed silver halide to metallic silver. I also
include any general (not image specific) density in a negative. This
definition also includes dye remnants and stains.
I once scrubbed the emulsion off of several 35mm films in order to measure
the base density so I could determine the true emulsion fog density by
difference. I was amazed at the presence of gray and lightly colored
density I found in the plastic of the base. Tri-X had a gray base density
of about 0.20 and a total fb+f of about 0.30 giving an emulsion fog level of
0.10. I have found that my fixer, even though it still fixes fine, will
contribute to fog if it gets too much age on it. This seems to be related
to sulfite exhaustion because it is reversible by adding more sulfite. These
older fixers also plate metallic silver on the inside of my storage bottle
so I suspect a high silver content may contribute to the fog.
JB
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