Re: 3 questions (one of them dumb)
----- Original Message -----
From: "Ryuji Suzuki" <rs@silvergrain.org>
To: <alt-photo-process-l@usask.ca>
Sent: Sunday, November 16, 2008 9:13 PM
Subject: Re: 3 questions (one of them dumb)
From: Judy Seigel <jseigel@panix.com>
Subject: 3 questions (one of them dumb)
Date: Sun, 16 Nov 2008 23:56:38 -0500 (EST)
A friend, masterminding a class mixing vandyke brown
emulsion, finds that when the silver nitrate is dissolved
in
the "distilled water" the solution turns somewhat milky.
I
recalled having had the same experience years ago,
ultimately discovering that the "distilled water" was
actually tap water, bottled as and labelled "distilled."
That's a very plausible story.
Friend said she'd been told there's a solution that tests
for "distilled" i(I have a note "Solenoid black from
NZ" --
could that be it?) Any info or advice would be gratefully
received.
You would want to test for chlorination. Silver nitrate
solution is a pretty good test for it. There are some
other
tests, such as ones used to test chlorination of swimming
pools.
So I looked up "chromogenic print" in the
two books I could find (two out of maybe 7 is a good rate
around here). The best definition was in Luis Nadeau's
"Encyclopedia," which explained that most "contemporary
color photographic materials belong to this category"
... also called "dye coupler prints," and "(improperly)
C-prints."
That is right. Dye coupler prints. Color prints made by
the
RA-4 process or its equivalent are good examples of
chromogenic prints. Similarly, color films used today are
chromogenic (dye coupler materials).
3. What is glycin? I know it isn't glycerine, more's the
pity, but it's not in Nadeau... There are of course some
photo chemistry books around here, now deeply buried in
the
Morton Street Mississippi Delta. So, I thought, it can't
hurt to ask.
http://silvergrain.com/labs/Glycin
--
Ryuji Suzuki
By this definition, which I think is correct, a
Cibachrome/Ilfochrome print is not chromogenic. These use a
dye destruction process rather than the creation of dye from
precursors contained in the emulsion or supplied by the
developer (as in Kodachrome).
My reply about Glycin was made before I saw this post.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com