Who was it who said "as soon as I hear the word culture I reach for my
checkbook"? Actually, I never quite got that, but I paraphrase anyway --
"as soon as I hear the word 'gospel' I reach for the 21-step". I could
quote you right from our very own FAQ the "gospel" I know isn't (eg that
hydrogen peroxide is a cyanotype intensifier. In fact it simply gives the
darker, oxidized blue immediately that otherwise takes drying & a day or
two to fully arrive. I don't claim discovery of that [it's in
Crawford] but cite it as familiar example.)
> > Assuming it's true, surely it would apply to carbon and related transfer
> > techniques more than gum.
>
> Why? The only reasons I can think of are that there are many more
> variables with gum that might simulate the appearence of contrast
My thought was that highlights are more likely to float off
with gum (especially with the smooth papers I print on) than with carbon,
where any hardening at all could remain as tone since it occurs at the
base rather than the top and that that difference might affect "curve."
As well, of course, as variables of emulsion and development you mention.
I believe silver sensitometry books give a paradigm and gear tests
accordingly, avoiding reciprocity failure etc. Given the EXTREMELY
various practice of gum, I would say generalities (gospel?) are
treacherous, or anyway a "curve" in one set of conditions might not be
replicable in others -- which is why I envision carbon printing as more
likely to convey dichromate "principles."
> Where I first learned gum printing in SE Ohio, summer time
> was a period of amazing humidity and it did affect the images, first by
> changing the drying time, and second once the emulsion was dry you
> could see the effect of even 15 minutes of additional exposure to a
> high humidity. (Two pieces of paper, coated at the same time and
> exposed sequentually to the same negative for the same 15 minute
> exposure, came out differently.) Some of this isn't unique to gum, but
> my point is that unless you have very tight controls over the
> variables, it is possible to interpret one or a combination of these
> effects as something other than what it is.
Yeah,that's what I mean. So name your variables!? (Incidentally,
do you recall what the difference in the gum print was from the extra 15
minutes wait in high humidity? I once tested length of wait and found
two hours made the best print, the nicest shadow separation -- but whoops
-- never noticed humidity!)
> > I wouldn't expect that what works for Cyanotypes would work equally well
> (or even at all) for gum as the emulsion is iron based, not
> chrome/colloid.
I wouldn't either, but mentioned cyanotype because it's
another non-silver medium that showed shoulder, suggesting curve or
anyway the shoulder part of it is not confined to silver.
> If you are trying to flash non-screened litho film that you are developing
> in litho A&B developer, I would imagine you aren't seeing much result
> as the transition between clear film and black is too abrupt for such
> a subtle technique to have any effect on the contrast.
I was trying to flash lith film developed as continuous tone with weak
Dektol (1 to
12) and very dilute HC110. With minimal agitation and short development
times this gives acceptable continous tone for most of our/my purposes --
it wouldn't satisfy a zonie, but with brush development, etc. can be pretty
good. (Obviously, though, the tendency is to contrast a bit on the much
side -- especially for gum -- hence the attempt at flash.)
> You might also try reflex printing. I've only read about it (and can't
> remember where - sigh...) Does any wise soul on the list have any
> more information? I believe this technique also had some effect on contrast
> (at least with silver materials).
I await word on reflex printing -- which I have NEVER read about!
Meanwhile (and notice I saved this for last when a lot of people probably
aren't reading any more because I feel like I'm sticking my neck out VERY
far) a few quick tests I did last night do suggest (notice how carefully
I'm wording this) what I take for a reasonably effective flash -- that
is, tone went up maybe a half step on the 21-step, with shadow steps about
the same. It's hard to tell by eye, and I feel my coating wasn't even
enough to be reliable -- I'll try again on a bigger paper so there's no
risk of coating fall-off near the edge. Also, the papers were just what I
had scraps of on the table -- a typing paper, lanaquarelle, and a
discontinued Rives drawing, and the soak was overnight. I'll also add
that whether a half-step is a significant difference is arguable - but it
sure looked like highlight density added from flash.
This incidentally was for flashes of 1 unit and 2 units on a 100 unit
negative exposure. The 5-unit flash through the back had no
effect whatsoever. I'll try that again starting at 10.
Will try to be VERY careful and controlled before sticking neck out
FURTHER!
Cheers,
Judy