Re: Gum dichromate issue

From: [email protected]
Date: 08/09/04-11:23:24 PM Z
Message-id: <>

Yes Christina I apply the curve contrast to the whole set of three negatives
but I am talking afterwards.
I think I read on Sam Wang article that the cyanotype Cyan color behaves
different from the other two gum colors (yellow and magenta), I may have it
read wrong but it made sense to me that printing with different techniques
should carry some kind of adjustment (if watercolor colors are different
between different manufacturers, what about different process?).
Anyway I may be wrong but some of my prints are right and the issue requires
more study.
So going to your other email, gum print is an art not documented that
requires investigation, experience, lots of printing and documentation.
Apparently everybody (also Sam Wang) agrees that there is nothing on
documentation and what is there is incomplete, right?
Please, where can I have a pick on Hubl's 1916 Three Color Photography ?
Any website?

----- Original Message -----
To: "Giovanni Di Mase" <>
Sent: Tuesday, August 10, 2004 12:53 AM
Subject: Re: Gum dichromate issue

> sometimes I change the curve factor (on photoshop which is the
> > contrast in a conventional film) on the Red negative but again I am
> > guessing. Why? I read somewhere that it was the most important of the
> three
> > negatives. Why? Is the first I use to print, then I go with the Blue
> (Yellow
> > pigment) and I start guessing the solar exposure time and finally I do a
> > third guess with the magenta pigment to "see" the picture.
> > The other issue is the pigment, remember "pure colors" do not exist, how
> > should this be dealt or handle in reality?
> > Giovanni
> PS I apply the curve to the whole negative before separating it into
> channels; all negatives print pretty much the same. If there is a color
> balance issue, I adjust exposure sometimes but more probably saturation of
> pigment (or type) which inherently will affect exposure and contrast
> somewhat.
> Chris
Received on Mon Aug 9 23:25:55 2004

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