Re: Lith film

From: Monnoyer Philippe <monnoyer@imec.be>
Subject: Lith film
Date: Thu, 11 Dec 2003 10:34:34 +0100

> I see a lot of people are talking about lith film. I'm not much
  aware of the previous discussions on this topic since the beginning
  of the list but I'm curious: I have a limited experience with lith
  film, but the few I tested NEVER gave me a long range of tones
  suiting palladiotype or platinotype. I even used very very soft
  developping agents and dilutions. The Dmax can be high, but a long
  halftone range was impossible. I should check the manufacturing
  specifications of such films, but in the meantime, let me propose 3
  hypothesis and ask you to react on it

First of all, later discussion in this thread has confused use of the
term "lith film," "high contrast graphic arts material,"
"panchromatic" and "orthochromatic." The meaning of these terms are
obvious from their names, but it is important to realize that there
are (were) panchromatic graphic art films, and more relevant to the
point is that there are (were) pictorial orthochromatic films. The
problem you described is best solved by using this class of products,
orthochromatic emulsion made for continuous tone reproduction. The
problem stems from the fact that you are trying to use lith film to
register very wide range of exposure.

Lith film requirements are very different from continuous tone
emulsion. Not only extremely high contrast is desired, but also very
sharp halftone dot rendition is required. Dmax is very high, typically
reaching 5 or so according to manufacturers' specs. In order to
achieve these goals, emulsion consists of silver halide of very narrow
size distribution (monodisperse emulsion). Such a production requires
precise pAg controlled double jet precipitation (that is, it's
difficult), along with careful selection of sensitizing techniques and
dopants such as rhodium complex salts or cadmium chloride.

On the other hand, continuous tone materials contain rather wide range
of crystal sizes, sensitized for more efficient latent image
formation, and stabilized so that the latent image is less susceptible
to react with developer oxiation products (such a reaction is
necessary for lith processing, and lith emulsions may even contain
catalysts for such reactions).

In last two decades, graphic art materials have increased the variety
of formulation because classic cadmium doped silver chlorobromide
processed in hydroquinone developer has become unfashionable from
manufacturer's point of view. So it is possible that some lith films
might behave more gracefully in low contrast developers (though I
wouldn't build too much expectation on that possibility).

I have personally used Arista lith films in camera and tried a few
developers like technidol-like developer and XTOL like developer.
Midtone rendition was beautiful but shadow was very rough even with
very generous exposure. Some people might recall early generation
tabular grain films. This might be useful for interpositive stage
because it contributes to brilliant highlights. (Flashing the
material before exposure might have helped the shadow rendition a bit
but I didn't try it.)

I saw you said you get density only a bit above 1. Lith films' Dmax
are very dependant on developer composition. With standard print
developer like Dektol, you should be able to go *well* beyond 2. Also
lith films respond very well to selenium toning for further Dmax
enhancement.

What is LC1 developer? Is the formula posted somewhere?

--
Ryuji Suzuki
"Reality has always had too many heads." (Bob Dylan, Cold Irons Bound, 1997)