Re: 3 questions (one of them dumb)
From: Judy Seigel <email@example.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
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
> 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)
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.
"Patriotism is the last refuge to which a scoundrel clings."
(Bob Dylan, Sweetheart Like You, 1983)