From: Judy Seigel (jseigel@panix.com)
Date: 07/07/03-12:55:30 PM Z
On Sat, 5 Jul 2003, Christina Z. Anderson wrote:
> Judy, in reference to dilutions, I cannot imagine why not mix the
> chemicals at their saturation point... in practice it doesn't make common
> sense to dilute am di to pot di's strength in your stock solutions. If you
> need less speed, you may use water in your coating mix, or less dichromate.
> And Sandy himself has said that you'd have to have pot di at 4.5% to match
> am di's speed at 3%, so it is not just a question of dilution.
Chris, you're preaching to the choir....
Of course I mix ammonium dichromate at full strength... not only does it
keep better (at least that's what they say-- I've never had a problem with
it spoiling), but it takes up less space. And of course I can then use it
at whatever dilution I want. In fact I rarely do print with it full
strength, preferring to dilute with maybe 1 part water to 2 parts
sensitiser.
As I've said many times, and contrary to the "conventional wisdom," I
find the coating goes on smoother and works better when it's thinner, not
thicker. It develops better too -- a thicker coating bulks up much more
when wet, & the least touch can be disaster. A thinner harder coat is just
generally less fragile.
I was simply trying to explain that the talk of "potassium di this and
ammonium di that" fails to mention concentration, which -- whatever other
"properties" the different chemicals may have -- is the over-riding
variable. I proved this by testing identical concentrations of the 3
dichromates. For speed, staining, and general virtue, I found little
enough difference among the 3 with the couple of colors and papers I
tested, to show that claims like "ammonium dichromate stains" & the like
are figments.
This concept is so obvious it shouldn't need explaining -- and it does
make me question every other sentence in those books (including "the" and
"and" as Mary McCarthy so famously said).
cut...
> However, when I begin to think of all the wealth of experience out
> there that I have read in old books and how maybe *one point* from one book
> is worth the time it took to read it, I just can't imagine why anyone
> *wouldn't* want to read historical accounts of the process! But that is my
> personality I realize.
I agree about the old lit -- delicious, fascinating, and endlessly
seductive -- but I think of it more as a magical mystery tour than a
process guide... Or a sentimental journey... There's always something
nice to stick in the file to try -- and to salute the pioneers. But my
finding... first in cyanotype, then silver iron, and then in gum ... is
that the old info rarely holds up.
Sometimes I can find the one condition that led the writer to assume it as
law, more often i don't... They didn't have the Internet to tell them hey
that may work with Turkey mill paper, but not with Rives !!! Or that may
work the same day, but a week later it's worse -- or any other myriad
variables I found that cancelled out most of the old cyanotype and
cyanotype toning lore -- which I tested much more completely than any of
the other old lit... Cyano was my first love & finding those old tomes in
the library (before microfiche, I had my hands on the true grail) I was
totally credulous ...
But, alas, I've never yet found anything really good that was lost -- tho
of course hope springs eternal -- this may be IT. But more likely, as one
of the dictionaries said about an early -- I think it was Artigue paper --
this has died out because (whatever) gives the same effect & easier.
Besides, as a rational use of time to become expert-- I covered a lot more
ground & got more reliable info with the 21-step and an organized
checklist of variables than the old literature...
sigh,
love & kisses,
Judy in blistering NYC
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