From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 06/30/01-12:11:40 PM Z
At 10:15 AM 06/30/2001 -0600, you wrote:
>Anyone know of an amount of anything I can add to pyro developer, or any
>developer, that will reduce base plus fog? The Konica Infrared that I shot
>is really dark, like a black army green. It's not fogged as in light leak
>or anything like that. I seem to remember benzotriazole or pot bromide
>being the addition in minute amounts?
>Chris
>
Fog can be reduced by the addition of Bromide or Benzotriazole.
Benzotriazole is more effective than bromide and affects the latent image
less for a given anount of fog reduction.
Grant Haist suggests for B&W films adding 0.2% Benzotriazole to developer
working solution:
Heavy fog, 40ml/liter
Light fog, 20ml/liter
Potassium bromide can be added in amounts up to 15 grams/liter however,
most film developers have much less than this, generally under one gram.
Large amounts of bromide tend to deststoy the latent image in low exposure
areas, effectively lowering film speed.
High support density is found in 35mm negative films due to a pigment or
dye added to the support to prevent conduction of light through the
support. It also has some anti-halation effect but most films have a
separate anti-halation coating which is decolorized by the developer or
fixing bath.
Pyro developers are not prodigeous foggers. I would suggest trying a
sample of the film in a conventional developer to see if it still shows
fog. By memory, IR films may be foggier than conventional films.
---- Richard Knoppow Los Angeles,Ca. dickburk@ix.netcom.com
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