[pure-silver] Re: tmx 3200 problem
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 31 Dec 2009 10:16:56 -0800
----- Original Message -----
From: "Eric Nelson" <emanmb@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, December 29, 2009 10:51 PM
Subject: [pure-silver] Re: tmx 3200 problem
Thanks Richard.
I was about to resend my question as it never made it to
my box, and yet was on the freelist archive. Mysteries of
the net.
So 15 gms of citric added to 1 liter of rapid fix for 2-5
minutes?
I've got 8 bloody rolls of this nonsense (all from the one
film run) so wiping them all isn't that appealing, nor
could I do them all thoroughly in limited time I'll have
to do it. I could see how it looks that wiping them might
be the ticket (unfortunately) as in the scan you can see
where I had handled the film on the leader when I hung the
film.
I've left 7 of the 8 rolls uncut in hopes that I could do
some treatment on the reels after which I'll have a chat
w/the Kodak boys as to why their products do such things
when you follow all the rules.
Eric
The time required depends on the material. The film
should be wetted, that is soaked in water for a few minutes
and then immerced in the reducer and agitated. Watch it to
seen when the fog is removed and stop the process as soon as
that happens. Treat the film in wash aid and wash. The
fixer-citric acid combination will also dissolve the image
silver so it needs to be watched carefully. Dichroic fog is
a deposit of "colloidal" silver. This is extremely finely
devided silver, the fineness of the grains is what makes it
dissolve much faster than the image silver, which, even on
printing paper or fine grain negative film is very much
coarser.
Colloidal silver is yellow by transmission, in fact,
the yellow filter layer in Kodachrome film is made of
colloidal silver. Because it is such a thin layer it
reflects light of the complimenary color. Because it is not
always uniform the reflected light may be of various colors
looking something like an oil slick and for the same reason,
that is, interference because of the thinness of the layer.
Dichroic fog can be produced in any bath containing
silver solvent. This is the case with many developers and
definitely with fixing baths. Some developers contain a
silver sequestering agent to keep dissolved silver in
solution. I suppose similar materials could be added to
fixing baths but are not common in B&W fixers. Dichroic fog
can also be produced in the fixing bath where a non-acid or
alkaline fixer is used along with a plain water stop bath.
The reason is that the carried over developer can convert
some of the dissolved silver halide in the fixing bath to
metallic silver which is then deposited on the film or
paper.
I am not convinced that the blotchs on these negatives
_are_ dichroic fog. A test using the fixing bath bleach will
help determine that. I have encountered this sort of
blotching on old film, well beyond its expiration date. I
don't know the mechanism. There are various other treatments
to remove stains from negatives but all carry the risk of
ruining the negative plus its necessary to know what sort of
stain one is dealing with. One of the common treatments is a
re-halogenating permanganate bleach followed by
re-development. Kodak describes such a bleach and the
procedure for using it in various publications. I probably
have this material and could copy it if desired.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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