From: Christina Z. Anderson (zphoto@montana.net)
Date: 09/22/02-11:36:45 AM Z
I continue to test mordancage. Now I am into pitting different
formulae against each other, and I found out a peculiar thing.
Cor, Nate, perhaps Jon, and I and maybe others on this list a while
ago were wondering how to avoid the stain that occurs on the paper from the
process, even in the borders of the print. I had previously posted my test
results that to get clean whites do the process a) under safelight, b) with
lower volumes of peroxide c) fix afterwards d) avoid chemical stain that
occurs when a print thru the mordancage solution is not cleaned enough of
the chemicals before it goes back into the developer by proper washing.
These still stand, in my opinion, and certainly for Coote's formula, but I
was interested in maybe prioritizing which ones are the bigger culprits. I
also cannot stand the fixing after the mordancage because it is so grossly
smelly when the fixer combines in the print with residual mordancage
chemicals. Sometimes a lengthy washing is not an option as the emulsion is
fragile.
But yesterday I was testing Clerc's formula against the one that I
always use, Coote's. Here are the two:
Clerc
cupric chloride 10g
citric acid 10g
water to 1 liter
Mix with equal volumes 10 vol hydrogen peroxide (3.4%).
Coote:
30g cupric chloride
80 ml glacial acetic
water to 1 liter
Mix equal parts with 20v to 40v hydrogen peroxide.
Clerc's was a very gentle formula, and didn't smell half as bad. (BTW,
I did try copper sulfate again with citric acid, and still no go, but I have
ordered some stronger acids to test it with. It would be nice if it would
work because it is a buck a pound at a ranch supply store, but it is always
in combination with nitric, sulfuric acids). It did not bleach much at all,
which was fine for me as I don't care that it bleaches, took longer to do
its thing, and is rubbed under hot water (90 degrees). But it was really
nice to use and gave great results, one being NO staining of the whites,
even under room light.
I tested to see if it might be the acetic vs. citric, and it still
didn't stain. I tested going right from mordancage to developer without
washing and got some stain that *looked* like normal chemical stain. But
this is my thought: there may be three reasons why no stain with Clerc's:
the *warm* water rub effectively cleaned out enough of the bleach solution
to not get chemical contamination, in effect, a more effective washing
between steps, or the lesser amount of cupric chloride, or the lesser
strength hydrogen peroxide.
Then it dawned on me as this may be the greater possibility, since I am
also testing mordants with dye mordanting. I realized that the stain of the
print only occurs in the gelatin areas of the print, including the borders
of the print. The areas where there is no gelatin do not stain. Hence,
could it be that the culprit is the stronger amount of cupric chloride which
in effect acts as a mordant to the gelatin which then makes all gelatin
remaining attract developer? In combination with the stronger hydrogen
peroxide which destroys more of the gelatin and therefore making it more
permeable to chemical stain? I would have to retest Clerc's with 1) stronger
hy per and 2) stronger cupric against the original to get my answer, but
those of you who have the time should test Clerc's and see what you get,
too. My process was to print a print a bunch of times and then use the same
print from the same batch to compare.
Whatever the case may be, those into mordancage may want to try Clerc's
formula and see if you, too, do not get stain. Maybe you could save me lots
of time and test these two variables for me :) Right now I am so sick of
copper up my nose I could puke. And Peter Marshall, any chance I may see
McFaden's article?
Chris
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