On 2/2/2011 23:53 PM, Frank Pittel wrote:
Richard wrote:
: On Jan 30, 5:57??pm, Frank wrote:
: I have a bunch of long expired film that I'm working on developing. To keep things simple I'm using D76 diluted 1:1 and am
: having problems with fogging. I know that Benzotriazol should help and that Potasium Bromide may help. Does anyone
: have experience with either approach or have other suggestions? I'm also interested in home much much I can add to
: the stock D76.
:
: --
:
: -------------------
: Keep working dumbo needs the money
: There is a chart showing benzotriazole use in _Modern
: Photographic Processing_ by Grant Haist. However, fog in negatives may
: look bad but for the most part just increases printing time a bit,
: provided its uniform. The film should be given a bit more exposure
: than if it was fog free. Increasing development will increase the fog
: along with the contrast so is not useful. Bromide will also reduce
: fog. It seems to have more effect on film speed than benzotriazole,
: the remarks above apply to it also.
: I have been able to get rid of moderate age fog on Plus-X sheet
: film by adding about 1 gram/liter to D-76 1:1. I shot the film at
: about half the rated speed. The unexposed margins were pretty clear.
: The prints were not any better than similarly exposed film developed
: without the added bromide.
Richard,
Thanks for the quick reply. If the film were unexposed I would pitch and get
"fresh" film. Alas, the film was exposed anywhere from 20 to 40 years ago and
there's no date on the rolls. There's a lot of fog and it seems to be hurting
the shadow contrast. To get any kind of reasonable print we and the others
working on the project are being forced to do a lot of printing with two (or
in some cases three) filters. One of the filters generally being a #5 so we get
some contrast in the shadows after using a 2-3.5 filter for the main exposure.
My hope is that by reducing the fog we would pick up the contrast in the shadow.
With minor exceptions the fog is uniform and "printing through the fog" is
working alright.
Frank
BTW - I ordered the Haist books a few days prior to my original post and have since
recieved it. For those that haven't seen or read it Grant Haist is an amazing
talent and I wish I got the books years ago!!
Some years ago, the founder of Film Rescue International
(see
http://www.filmrescue.com/ ) used to participate in
this forum. He had, through long trial and error - together
with a good knowledge of photochemistry - put together a
process for minimizing film in such situations. If top
quality recovery is your objective, you may want to contact
Film Rescue.
He shared some information with me at a time when I was
trying to develop some 80 year old negatives (Richard
probably recalls that trial), but I promised I would not
reveal his proprietary information. And, I have to confess,
I lost the specific email he sent, and only have fragmentary
information now anyway.
I also note that the following is a patent filed in 1966
(now in the public domain) which describes a method of fog
reduction in silver halide films.
http://www.freepatentsonline.com/3244522.pdf
Attention should be paid not just to the particular forms of
xylene or benzene to be used, but also to the specific
development processes described.
--
Francis A. Miniter
In dem Lande der Pygmäen
gibt es keine Uniformen,
weder Abzeichen, noch irgend welche Normen,
Und Soldaten sind dort nicht zu sehen.
Siegfried von Vegesack, "Es gibt keine Uniformen"
from In dem Lande der Pygmäen