From: Judy Seigel (jseigel@panix.com)
Date: 08/19/03-10:50:35 PM Z
On Sun, 17 Aug 2003, Christina Z. Anderson wrote:
>
> As I also stated in a post a couple weeks ago, 100% sodium
> dichromate--100%!!--is not that fast. I found it to be less fast than
> ammonium dichromate, which blew me away. I will certainly retest this and
> see if I am mistaken, but the assumption that 100% sodium dichromate would
> be, let's say, 3x as fast as 30% ammonium dichromate does not seem to be
> true with my limited testing. I will certainly redo this test, because I
NO -- you're missing the point. I'm not talking about ***FAST***, as in
exposure. I'm talking about the effect of the dichromate per se. If the
dichromate causes pigment stain it would be irrespective of "speed," and
100 times as much would cause, maybe not 100%, but a lot more stain.
When I tested the three di's... ammonium, potassium, sodium... I used
21-steps... with all three solutions adjusted to the same strength, 10%.
The "speed" was for all practical purposes about the same, but the sodium
di stained noticeably more than the others, which hardly stained at all.
I daresay this would vary with the gum (which I repeat repeat repeat I
have found to be a major variable in staining, a factor generally ignored)
but still I suspect that across the board a mix with sodium di would stain
more....
> have a liter of the stuff sitting around and I don't plan on using it in my
> practice except to do silly tests :) but it really surprised me. The only
> thing I could think of was that the thickness of the syrup held back light
> more than one thought, or maybe just maybe my am di that day was SOOOO hot
> (doubtful) that more went into solution. So, to be fair, I'd really have to
> make sure my room temp is around 70 and retest. To me, the primary reason
> for not using sodium dichromate is that if you use a saturated solution
> you're using way too much dichromate for the same result--no more "bang for
> your buck".
So then why did this great guru gum printer do it ???? I don't recall any
other gum printer using 100% na di.... Of course I'd have to test the 100%
for speed before I'd take your word that it isn't faster... and not having
any on hand, think I'll pass ... but doesn't it make you wonder about Mr.
A?
> > As for how it got into the canon -- I've said this before: It was the
> > ZEITGEIST !!! In 1939 (year of Henney & Dudley) Kodak was gaining
> > ascendancy with its factory materials. Kodak types were coming up with
> > all these tables and charts and curves and of course when you sell factory
> > film & paper you *have* to provide the tables & charts & curves showing
> > how to use them.
> <etc., big snip>
>
> This I find FASCINATING.
>
> > Otherwise they would have had Franklin Jordan, actually better known at
> > the time & who knew more about gum printing, do the chapter...
>
> I find this assertion interesting: Jordan's book is written very
> cavalierly: a bit on the "flippant" side. I wonder if they didn't
> appreciate his jocular attitude?
Chris, Franklin Jordan was the editor for many years of the American
Annual of Photography, among other offices and distinctions -- at least
the rank of the editors Henney & Dudley, who were at the time relatively
obscure... That they were humorless Kodak types probably goes without
saying, but however and in any event, what you call flip, many would
consider quite charming and lively, and I daresay was taken that way at
the time in the field. Anyway, he was more important than those Kodak
guys, and the top dog gets to make the jokes.
HOWEVER, Jordan didn't give the SYSTEM, the NUMBERS, the way Anderson did
-- and it was that magical auto-system everybody fell for -- almost every
last one of 'em !!! Remember his promise that he would save you from "by
guess and by golly" ???!!! Of course no gum printer really guesses after
the first couple of prints... they probably test a bit of the gum-pigment
mix on paper before adding the dichromate & have a sense of how it will
print, or have an idea of the range of pigment density they want. I also
assume that the adroit & artful gum printer varies the pigment ratio
according to which layer is needed to do what... So the whole notion of a
set "right" ratio is useless, not to mention deadly & deadening... But
then Anderson seems not to have made enough gum prints to get the feel of
the method anyway....
> I've been using room light and have no fogging. It'd have to be
> accidental exposure stronger than roomlight. But technically, how can we
> know whether it is fogging or just too much exposure?
Technically it's fruitless to do tests without a 21-step in there --in
fact I do mine mostly with 21-steps -- INFINITELY more info than a
"negative" which is in fact just random tones,,,, while saving lots of
paper, water, paint, etc. etc. And I have never yet seen a gum exposure
that "fogged" the top steps in a 21-step.... That would I suppose be
possible -- at about 10 times the right exposure -- but rare.
> it--insolubilize the gum enough so that pigment stays where we want it,
> but not too much so that it stays in the highlights. And this can
> happen with or without exposure, as delineated in the outline.
In theory probably, but unless you've got a joker in there somewhere
rarely in practice -- once I broke my students tendency to heat dry the
emulsion... which somehow seems almost reflexive when they're had platinum
printing first... Don't think I've ever seen insoluble otherwise except
with cheap offbrand paints.... Except one time I myself ground the
emulsion into the paper too hard & it didn't clear -- but you left that
out !!!
Judy
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