From: Ryuji Suzuki (rs@silvergrain.org)
Date: 09/23/03-01:31:54 AM Z
From: Steve Bell <sbell1@artic.edu>
Subject: Autochromes
Date: Tue, 23 Sep 2003 01:21:12 -0500
Autochrome got mentioned in pure-silver list a couple weeks ago but
with no technical discussion... just for records - not worth searching
for it.
> so does anyone have any info on how possible this process is today?
If you can make color matrix layer just like Lumiere's, the rest is
just a matter of making a fast, extremely fine grained, panchromatic
reversal plate emulsion, which is probably not terribly difficult. I
do not think you can buy any panchromatic emulsion or any emulsion of
this speed, so you have to make one yourself. But again I think the
emulsion is the least of the problem.
The color matrix might be easier to make like Dufaycolor film. I
checked this keyword (as well as Agfa color plate) in google but
nothing came out. I'm not old enough to know them real time, but these
are explained in some details in Baker (1948) Photographic Emulsion
Technique 2nd ed.
Dufaycolor film used color matrix consisting of colored lines of about
500 lines per inch instead of Lumiere's method, allowing the use of
coarser grained emulsion.
Some high-resolution inkjet printers may be capable of making a
pattern like that used by Dufaycolor film, to which panchromatic slide
emulsion is to be coated and exposed through the pattern. But I am not
sure if you can find inks made of pigments that are resistant of
post-exposure processing of the film. Or you might want to do
as closely as Lumiere's method. I think glass support must be used for
all but low-resolution Dyfaycolor type matrix process.
Baker explains that the fast reversal emulsion for Autochrome-like
processes should contain plenty of tiny grains that are not meant to
be exposed in camera, but are to be developed during reversal process
to provide excellent and high resolution blocking of undesired
colors. Anyway, the clever technique Baker talks about for the
emulsion part isn't difficult to anyone who makes fast, dry plate or
film emulsions. Making a good color matrix seems much more challenging
to me.
Baker refers to E. J. Wall's "History of COlor Photography" for
problems with color matrix techniques.
-- Ryuji Suzuki "Reality has always had too many heads." (Bob Dylan, Cold Irons Bound, 1997)
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