Re: direct carbon or gum bleach development
Keith, it's somewhat confusing because "carbon black" is sometimes
used as a general term to designate black pigments made from carbon
and sometimes to designate a specific pigment, PBk7, which is why
pigment numbers are so important. Lamp black pigment is PBk6; PBk7
is called sometimes carbon black and sometimes furnace black and is
sometimes given the marketing name "lamp black," but isn't actually
lamp black. According to some sources, PBk7 is darker and
velvetier than PBk6.
I've been sick for weeks with a flu thing that turned into bronchitis
and haven't got down to the workshop to continue my experiments with
this. But because I'm still interested in exploring this, I wonder
if you could say a little more about what's not working for you; is
it "just" staining, or is it a problem with the bleaching too? Thanks.
Katharine
On Jan 2, 2008, at 7:41 AM, Keith Gerling wrote:
Thanks Marek,
Cold here in the midwurst and I'm staying put and making do with what
I have at hand (which does not include Fabriano). But carbon black is
the same as lamp black, correct? And I also have some pure graphite,
and both of these stain what I've been using, which include Masa (as
predicted by Loris), gessoed paper and wood, and the flip side of
other gum prints on various papers (which, come to think of it does
include Fabriano, albeit many times immersed in water, so it isn't
like what you have used).
Thanks for the offer. I'll play around a little more. The picture
you posted was on unshrunk paper, correct? What impresses me the most
is not so much the bleaching (without seeing a before-and-after it is
hard to tell what that is) but the intensity, shapness and grain of
the print (resembling, come to think of it, a Ralph Gibson...) What I
would very much like to do would be to produce duotones by using this
process over a Van Dyke print. What are your thoughts on that?
Thanks!
Keith
On Jan 2, 2008 8:09 AM, Marek Matusz <marekmatusz@hotmail.com> wrote:
Keith,
I have been using carbon black powder from Daniel Smith. Gum bleach
development requires higher density negative then normal gum. I
would say
something more like palladium negative density would be fine to
start with.
If you can email me a scan of your work I can perhaps troublesoot it.
Marek
Date: Tue, 1 Jan 2008 19:47:57 -0600
From: keith.gerling@gmail.com
Subject: Re: direct carbon or gum bleach development
To: alt-photo-process-l@usask.ca
Hi Marek,
My attempts look atrocious. What kind of pigment are you using
for this?
thanks!
Keith
On Dec 20, 2007 4:05 PM, Keith Gerling <keith.gerling@gmail.com>
wrote:
Awesome, Marek. This is what I want MY prints to look like. Forget
all that multi-coat nonsense.
On Dec 20, 2007 2:28 PM, Marek Matusz <marekmatusz@hotmail.com>
wrote:
All,
More experimentation with gum printing and bleach development.
I was intrigued by Loris's results with using unsized paper. I
thought
that
it would give a rather bad stain. My tricolor gum practice
certainly
led me
to believe this. However on numerous occasions I did observe that
edges of
paper that I used which did not have gelatin size gave a
darker, more
uniform black. SO last week I tried to use single sized paper,
fresh
and
unsized Fabriano Artistico, and a throw away gum print that has
been
soaked
over and over, but had a reverse side of Fabriano paper quite
clean.
My
overall conclusion with this set of prints is that I liked unsized
paper and
soaked paper best. They gave crispier prints. Perhaps this
technique
likes
the gum to be tied up with the fiber of the paper and the bleach
development
can give clear paper base. So I would advocate use of straight
watercolor
paper, no need to size. I have not tried any other brand, but I
should
have
some at hand and will try next printing session.
I have also experimented some more with pigment density. I had
a more
concentrated carbon stock of 3.75% carbon in 14 baume gum, that
is 50%
more
then in my last set of experiments. The solutions are left over
from
dozens
or maybe hundreds of experiments done in the last two years.
Once the
water
dried out this would result in 3.75/0.27=14% carbon/solid gum
mixture
(I
assume 14 baume gum is 27%). This is definitely black black.
Beautiful
velvety matte texture of the deep black to take your breath
away. Scan
of
the print here. This print was made on unsized Fabriano Artistico
paper
http://picasaweb.google.com/marekmatusz1/GumBleachDevelop/
photo#5145909559997921266
The mid tones are a little bit darker on this screen that in
reality.
Maybe
even the two tones of black on the very edge are visible. Very
outside, had
most exposure (I uped the exposure to 6 minutes from last time)
and
next to
it is somewhat lighter edge from exposure through blank part of
transparency
(Pictorico). This is a further illustration of how a fine tonal
gradation
can be achieved with this method.
I have also included an detail of the print scanned at 300 dpi:
http://picasaweb.google.com/marekmatusz1/GumBleachDevelop/
photo#5145909521343215586
Happy printing
Marek
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