U of S | Mailing List Archive | alt-photo-process-l | Re: Printing gum with little pigment

Re: Printing gum with little pigment

Agree with Marek here.

Marek, I'm trying to remember where I have a set of such test strips
that I could quickly scan for you.

In the meantime, I have something a little different, that may or
may not be helpful to the discussion. What I have is reflection
density readings for a range of pigment concentrations. This doesn't
show the number of steps on a Stouffer tablet, but it does show the
actual tonal range (of course for gum there's no particular
connection between Stouffer steps and tonal densities).

For my demonstration I used PBk11, which has become my favorite
black; I printed it at six different concentrations. The two
lightest concentrations gave the shortest tonal range, .50 and .62.
The next three all gave a range of .75, each moving progressively
down the scale. The heaviest mix doesn't really count, because I
overexposed it and then subjected it to extreme measures of blasting
it with hot water under pressure and scrubbing it with a wire brush
to bring out the tonalities; it came out at a range of 1.00, but as I
said, I'm not sure it counts because the tones weren't developed
naturally but forced out of the gum by sheet will power and cussedness.

Anyhow, I printed a sample print rather than using test strips, just
because I think most people who aren't used to using step tablets
find an image more intuitive to understand; those test prints and the
density data are here, the first visual on the page:



On Jan 16, 2009, at 3:05 PM, Marek Matusz wrote:

Here is where the argument breaks down. What you consider a weak/
moderate pigment I might be using and defining as strong. The only
way for you to convince yourself of the validity of your assumption
is to cut the pigment concentration in half or quarter and print
something side by side. I am looking for people that have done it
already and can share the actual prints/test strips.

> Date: Fri, 16 Jan 2009 22:01:40 +0200
> From: mail@loris.medici.name
> Subject: Re: Printing gum with little pigment
> To: alt-photo-process-l@usask.ca
> Thanks for sharing these Marek.
> I regularly print gum from negatives calibrated for Cyanotype,
> like log 1.5 ES (= 15 steps with the 31-step tablet - each step =
log 0.1)
> using weak / weak-moderate pigment concentrations, getting full
> starting from shadows up to the highlights. So I definitely
believe in
> less pigment = more range -> it's in parallel to my experience...
> Regards,
> Loris.
> 16 Ocak 2009, Cuma, 7:33 pm tarihinde, Marek Matusz yazmış:
> >
> > Hi all
> > I was waiting for a dry spell to bring this up. A while back
Judy made a
> > statement that printing gum with little or no pigment allows
for a very
> > e xtended range. I looked back through the Post Factory issues
and really
> > could not find examples. Hey Judy thanks for sparking my interest.
> > Since I was messing around with the post-flash and was getting
> > results in extending tonal range of the print I decided to do some
> > experimentation and actually print some test prints.
> > http://picasaweb.google.com/marekmatusz1/ExtendedGumRange#
> >
> > Two sets of tests are done with same water/gum/dichromate but
> > pigment concentrations. I have made different exposures and
tested two
> > development times. I used indantrone blue which is a wonderful
dark blue
> > and non-staining. I can not see that low pigment concentration
extends the
> > rane of gum print, to the contrary it allows less steps to be
separated on
> > a standard step tablet. One of the tests is also a good
illustration of
> & gt; how delicate highlights with dark shadows can be printed
with the same
> > negative with the postflash.
> > Anybody else want to chime in. It would be great to see some
> > illustrations. A picture is worth a thousand words.
> > This contrast vs. pigment issue has been on my mind for a while.
> > Marek

Windows Live™: Keep your life in sync. Check it out.