RE: digital negatives for cyanotype

Judy Seigel (jseigel@panix.com)
Mon, 22 Apr 1996 14:53:00 -0400 (EDT)

On Tue, 23 Apr 1996, Philippe MOROUX wrote: > The negative ( A3 / 42x30
cm) was good for gum printing, because of the slight > diffusion given by
the gum process. Used for kallitype, it showed the very

Watch it buddy, those are fighting words here at the OK corral. About
"slight diffusion of the gum process," I mean. That "diffusion" is
optional and circumstantial, as I have pointed out a time or two.

In fact, experimenting with a digitally-made negative, I got serious
all-over blotches in a gum print, due to *dot gain* I supposed.
There was an overall pattern in the negative, visible only by loupe, not to
the eye. The particular gum mix I was using was very sharp & clear with
a contone negative, but with the digital added enough to each dot so that
clusters of them appeared in the image.

I switched to a finer emulsion (made from paint rather than dry pigment)
and the blotches disappeared, but that mix was too flat. I imagine it
could be adjusted & presumably I will but I have to get the tip of the
iceberg off first.

> I didn't had the occasion of working again with this material, and I know
> nobody who ever tried at a better resolution. But I would appreciate if an

A woman I know, former computer graphics graduate student, now
computer-imaging teacher at Pratt, used the film recorder to output
negatives which were then, as I recall, enlarged onto silver contone film.
Seemed to work fine. (She's probably returning to France where she lived
last year, in one of those mountain villages where they bring electricity
in by carrier pidgeon. I'll get her e-mail address there.)

Judy