U of S | Mailing List Archive | alt-photo-process-l | Re: gum "curves"

Re: gum "curves"

On Oct 27, 2006, at 10:33 AM, Henry Rattle wrote:

Just as a person who is currently experimenting with curves for my
gum-over-cyanotypes, my take on this debate is that the most powerful use of
Mark's curves system is for printing methods (such as platinum and
cyanotype) where post-printing manipulation is not really possible. In those
cases you can take an original with a full range of tones, and using your
own chosen processes (printer, negative substrate, exposure device, paper
etc etc) produce a digital negative which will make a full-range print with
good separation right across the tonal range, and no test strips needed.
I've done it with cyanotype and it worked just fine right off the board.
But the question is, does it work that way with gum? Given the discussions I've seen, that's not the case. Even after you've developed this negative, there's still some tweaking and fiddling and fudging with exposures and so forth, depending on conditions.

I think there's some misconception at work here; I have an intensely classical mindset, and my objection isn't that the curves thing is too predictable or not romantic enough; it's that as far as I can see, it's not very predictable or repeatable for gum. Otherwise why would you have people using PDN and still adjusting their development or exposures to conditions, and saying things like "my method is predictable until it's not predictable" which as far as I can see is exactly the situation we're all in, curves or no curves. Anyone who thinks that my approach to gum is random, unpredictable, chaotic, or romantic doesn't understand anything about how I go about printing gum, or how consistent my prints are. No, it's not Zen vs Calvinism that's the underlying debate here; it's whether claims that are made for an approach are justified.

As far as post-exposure control, I don't indulge in any post- exposure manipulation whatever; I simply print and still-develop and that's it. So all the concessions about post-exposure control don't have any relevance to my comments about curves.

If people like the curves approach, be my guest. . just don't expect me to follow suit, when there's no evidence that this is a superior approach in some objective sense that demonstrates its superiority in superior prints, and so far no evidence from my own observations that this approach would improve my own prints in any way, or make them more consistent or my process more reliable than they already are.


With gum you have a choice, and I guess it depends on personality type and
your approach to the art. Because you have so much post-exposure control
with gum, you can "manage" your print right through until it's dry and even
beyond. On the other hand, if you prefer to put the effort in earlier in the
process and then have a result that is predictable with the minimum of
hands-on manipulation, then you'd probably think that the effort involved in
analysing your workflow and materials, generating curves (it's not very
hard) and then keeping everything as constant as you can, is well justified.

(Of course, I appreciate that the words "gum" and "constant" are not often
found in the same sentence... In the lab we used to call it TMV - Too Many

I seem to recall Robert Pirsig exploring the difference between what he
called "classical" and "romantic" mindsets in Zen and the Art of Motorcycle
Maintenance. I suspect that that's the underlying debate here.

Best wishes


On 27/10/06 17:32, "Katharine Thayer" <kthayer@pacifier.com> wrote:

On Oct 26, 2006, at 8:42 PM, Judy Seigel wrote:

I also suspect that Katharine is right -- that every change of
pigment, and mix, every new batch of sensitizer (they tend to lose
speed as they age), every new purchase of gum (which changes
drastically from maker to maker, and also season to season) every
new tube of paint (they've been known to perform differently, even
when officially the same) AND every MIXED color (which would surely
change the "curve") would require a new curved negative.  AND if
you decide to avoid such changes as far as possible to keep your
nicely curved negs viable, you will be, as far as gum printing is
concerned, tying one hand plus 3 fingers behind your back.

I didn't just make that up out of thin air, that's been my
understanding from the "curves" contingent all along, that a curve is
specific to a particular set of printing conditions, including
emulsion, paper, equipment, and environmental conditions (and a
particular inkjet printer) and to use the system properly you need to
make a new curve every time you change any part of that equation.
I remember one discussion where I was arguing that I get perfectly
good results using the same curve (no curve) and adjusting the
exposure for different pigment mixes and conditions, and wondered if
just printing the same curve with different exposures might achieve
the same end (in the print) as printing different curves with the
same exposure.  I was told  that holding the curve constant and
changing the exposure  doesn't yield the same results at all as
holding the exposure constant and making different curves for each
pigment,  the implication  being that doing the latter gives such
superior results that if you're not doing it that way, you're just
not really up to speed with gum printing (although as I keep saying,
surely if this were true, the gum prints coming out of this system
would be so superior to gum prints ever made heretofore,  that it
would be apparent to all... frankly I just haven't seen it).  Since I
hadn't done that comparison myself, I couldn't argue with the
assertion.  And recently someone was telling us that the thing about
the currently fashionable curves system that makes it superior to all
others is that it is geared precisely to the conditions and materials
of one's specific situation.

I don't know how it could be otherwise, since the curve is generated
for a specific printing protocol, and as we all know, different
conditions, different materials, different equipment, different
pigment mixes, etc, require different printing protocols.