[pure-silver] Re: Oh How I Miss This Paper
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 27 Jan 2011 14:42:56 -0800
----- Original Message -----
From: "richard lahrson" <gtripspud@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Thursday, January 27, 2011 1:09 PM
Subject: [pure-silver] Re: Oh How I Miss This Paper
Hi!
Even if the paper is old and fogged, can't this
be cleaned up? I'm thinking of more restrainer.
Best, Rich
Its possible to salvage some paper using fairly strong
benzotriazole but there is a limit. At some point the speed
and characteristic of the paper is just compromised too
much. Fog mostly comes from a very slow continuation of the
"ripening" process the emulsion goes through during
manufacture. Some halide particles become developable even
though not exposed. To some degree restrainer can prevent
them from being developed, and restrainer and anti-fogging
agents are added to the emulsion for this purpose as are
chemicals intended to prevent or slow the fogging process.
However, we are talking about paper which has not been
manufactured for more than ten years and some may be decades
old. While it may be possible to make prints on it the paper
will not look it did when new. Paper and film is perishable.
If kept in frozen storage it may last a very long time but
at normal room temperature the life is pretty limited.
Opened packages fog quite fast, perhaps because of the
effect of oxidation.
Benzotriazole is more a more effective anti-foggant
under most conditions than bromide and has less effect on
speed.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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