[pure-silver] Re: tmx 3200 problem
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Wed, 30 Dec 2009 14:18:34 -0800
----- Original Message -----
From: "Mike Kirwan" <mkirwan@xxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Wednesday, December 30, 2009 10:17 AM
Subject: [pure-silver] Re: tmx 3200 problem
Eric:
Sorry to jump on this thread so late, but from the image
of the negative
strip you posted, the base density looks really high. I
had a similar
problem with the Ilford equivalent. Poor storage was the
cause and this
stuff really does not have a great shelf life compared to
FP4 or Pan F.
Any chance can you remember how old the film is?
Mike
What I see is the normal anti-lightpiping pigment in the
base. Most 35mm B&W negative films have this. It is to
prevent light from being conducted through the support when
one end is exposed to strong light, as is commonly the case
when loading 35mm film. This is a pigment, not a dye and is
incorporated in the support material so it is permanent and
not removed by processing.
Color films use a different arrangement for
anti-halation consisting of an opaque layer coated under the
emulsion. This serves the dual purpose of protecting against
light-piping and is removed during processing.
To check for emulsion fog on pigmented support one needs
a sample of the film which has been fixed out without
exposure or development. A comparison will show if the
emulsion is fogged. The film must not be light-struck since
that will produce some photolytic silver giving a false fog
level.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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