Keith,
Seems like the cold train has arrived in Houston. Iit was chilly 32F this morning. I have done a bit more printing this weekend (bleach developed gums) with burnt umber pigment. Every time I learn a little bit more, which means that mu failure ratio is not that hight now. Actually multiple prints at the same printing session are very consistent, much more then traditional gum.
As far as some of your questions: lamp black and carbon black should be colose to the same thing (or are the same thing). They are the very dark carbon pigments. I am not quite sure about printing over VDB with such a heavy pigment load. For one thing the gum image is so dark (in my practice) you would not be able to see anything below it. Actually I have done less pigmented mixes as well, so that might not be a valid concern. Of more concern would be bleaching of VDB silver image during chlorox development phase. You might try a test strip too see if the VDBgets bleached by chlorox.
As far as papers are concerned I think that the bleach develop gum process requires a very thin layer of gum that is anchored in a paper base. That is the interaction od paper fibers and emulsion is critical. I accidentally printed an image on very heavily coated paper (12% gelatin) and I got white spots during development where the image just dissolved, mostly in highlights. right now I am printing on unsized papers with most consistency.
Marek
> Date: Wed, 2 Jan 2008 09:41:18 -0600
> From: keith.gerling@gmail.com
> Subject: Re: direct carbon or gum bleach development
> To: alt-photo-process-l@usask.ca
>
> 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
> > > > >
> > > > >
> > > > > ________________________________
> > > > > Don't get caught with egg on your face. Play Chicktionary! Check it
> > out!
> > > >
> >
> >
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