By accounts I have reference to; that is personal conversations and
experience some RC Papers from 1980's and before do have this issue.
Especially machine printed RC silver based papers- Like Agfa RC's.
Not fixing properly always can produce the issue: bronzing, the silver
will migrate out to the surface if the fixer does not seal the top most
silver molecules, having an airspace between paper surface and glass
also seems rather im****tant.
Its probably also a result of how certain papers were once made with
regard to the placement of the silver layer within the emulsion.
In article <475f1159$0$2551$4c368faf@[EMAIL PROTECTED]
>,
"Pieter" <pvcl@[EMAIL PROTECTED]
> wrote:
> I don't know that RC has a history or a current problem like this, but I
> think the suggestions offered below are excellent. I immediately
thought of
> incomplete fixing or incomplete wa****ng, but mounting materials could
also
> be a problem as suggested ny Nicholas below. I have never had a problem
> myself, but I frequently test fixer and fix with a timer then use an
> effective print washer. Hypo eliminator would remove any fixer left on
the
> paper. I have only seen strange coloration and fading occur as the
result
> of chemical contamination, usually in group darkroom settings.
>
> "Nicholas O. Lindan" <see@[EMAIL PROTECTED]
> wrote in message
> news:13ltrm5au2v3c04@[EMAIL PROTECTED]
> > "Jim Stewart" <jstewart@[EMAIL PROTECTED]
> wrote
> >
> >> after about a year,
> >> the black areas turned an ugly mottled gold
> >> color. I used Ilford chemistry and Mitsubi**** Gekko
> >> paper.
> >
> > This happens to RC paper - the reason for it is a
> > matter of debate. Titanium dioxide in the paper
> > reacting with UV light is one current suspect,
> > sulfur from pollution or the mount material is
> > another.
> >
> > The history of RC materials is one of
> > problems followed by Kodak/Agfa/Ilford/xxx
> > claiming 'we have fixed the problem'
> > followed by either the reemergence of the
> > old problem or the creation of an entirely
> > new problem. I greet any explanation or
> > solution with suspicion.
> >
> > Agfa RC was very prone to bronzing. I haven't seen
> > any on Ilford RC but that may be a matter of luck/time.
> >
> > To keep it from happening again you might try using
> > Ilford paper. Err on the safe side: use fresh fixer
> > for 5 minutes, a hypo eliminator, wash for 1/2 hour.
> > There are all sorts of fast processing methods but
> > the old methods are known to not contribute to the
> > problem.
> >
> > If the picture is in a frame then make sure you
> > use acid free board for the mat and mount board -
> > "4-ply 100% cotton museum board" is considered the
> > safest: the core of the board should be pure white,
> > not grey.
> >
> > --
> > Nicholas O. Lindan, Cleveland, Ohio
> > Darkroom Automation: F-Stop Timers, Enlarging Meters
> > http://www.darkroomautomation.com/index.htm
> > n o lindan at ix dot netcom dot com
> >
--
Reality is a picture perfected and never looking back.
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