Re: Reversal processing for enlarged negatives

From: Loris Medici <loris_medici@yahoo.com>
Subject: RE: Reversal processing for enlarged negatives
Date: Wed, 24 Mar 2004 12:45:39 +0200

> Then this is not good for alt. process printing. What about KRST toning?
> Will be KRST toned negastives suitable for alt. process printing? Will
> KRST provide any advantage over Dektol / Bromphen or Multigrade print
> developers (for redevelopment)? I liked Ryuji's point: "you will
> redevelop more completely with KRST: tiny grains that't won't fog in
> room light and won't develop in the second developing solution (say...
> in Dektol and such developers), will be developed with the toner". What
> will be your comments on this?

I think the answer to all these has to wait for someone to figure out
the cause of high UV density with the material redeveloped in sepia
toner. (But you can always try it anyway.) I'd look at (1) whether the
high density is imagewise or completely uniform, (2) whether there's
something in the "clear" part of the processed film both chemically
and through microscope with diffuse field light.

Hypothesis 1 is that the UV density is due to small silver sulfide
particles which would not be developed by ordinary developers but
developed by sepia toner. They are there but somehow don't bother in
visual spectrum.

If the density is built by silver sulfide, it should be removed by
thiourea in acid solution, or sodium potassium tartrate mixed with
lemon juice. Well, the latter is useful in cleaning cloudy or
blackened silverware.

If this is really the case, liberal use of thiocyanate in the first
developer is probably the way to go.

Hypothesis 2 is that sepia reacted with something else that is present
in the film.

Also, the simplified method sounds interesting but it won't work with
KRST.

> My problems with lith negatives are: I see very ugly big black dots here
> and there and general grain clumping in dense parts of the negative
> (everytime) and I have high base fog (sometimes - I guess the high base
> fog is caused by the fact I don't place a black sheet under the
> negative). What can I do to have smoother tonality? (please note that I
> use 35mm film - not medium format, so my enlargements are around 8x -
> 10x scale)

When you say base fog, you mean the minimum density in the heavily
exposed area? That, again, should resort to thiocyanate in the first
developer.

Like I said, lith films come in a huge range of flavors (depending on
the product), and one technique may not work for all products. So I'd
recommend to find what works for your film...

Some (old) lith films use chlorobromide emulsion with cadmium and
other contrast enhancers. Cadmium is said to do a lot of different but
mostly good things from modifying the grain size distribution of the
emulsion (keeps lots of tiny crystals) to catalysis in development
process (promotes infectious development)... but cadmium is out of
fashion and several versions of cadmium-free lith emulsions
appeared. At the same time hydroquinone is trying to be out of
fashion, and patent literature is full of hydroquinone-free high
contrast lithographic developers. Some lith emulsions are said to use
a small amount of iodide, which helps to make grain size more uniform.

A huge difference is apparent between APH and Kodalith. APH develops
very fast, gives high contrast in pretty much any developer, and fixes
very fast in sodium thiosulfate fixer. Kodalith is a faster film, and
takes many minutes to develop in low contrast developer, very easy to
build dichroic fog even with just sulfite when exposure level is very
high, and takes long time to fix.

--
Ryuji Suzuki
"All the truth in the world adds up to one big lie." (Bob Dylan 2000)