RE: Silver chloride contact printing papers - AZO

A sufficiently great mass of silver chloride darkens when given a
sufficiently heavy exposure to light, as a consequence of the halide being
reduced by light to silver metal. Printing-out papers have a huge load of
silver, so they darken markedly compared to developing-out papers (which
darken faintly).

Silver halide crystals are much tinier than grains of developed silver. A
developer effectively "amplifies" an exposed halide crystal by binding
silver ions to it, yielding a grain of filamentary silver some 10 to the 7
power greater in mass than the original crystal.

POP image colors tend toward the reddish, because the undeveloped grains
making up the image are so fine they mess with the color of the light they
reflect, while developed images tend to be considerably darker, sometimes
quite black, due to their considerably greater coarseness.

David Foy

-----Original Message-----
From: Loris Medici [mailto:loris_medici@yahoo.com]
Sent: Monday, January 26, 2004 10:05 AM
To: alt-photo-process-l@sask.usask.ca
Subject: Silver chloride contact printing papers - AZO

I was reading an article about AZO paper and in the article it's written
that AZO is a silver chloride contact printing paper. AFAIK, salted
papers and albumenized papers also are silver chloride papers. The AZO
article also mention developers like Amidol, Dektol... that's where I
got confused; according to my limited knowledge, salted and albumenized
silver chloride papers are POP papers - there's no development involved
but only a wash to get rid of unexposed silver chloride, then toning and
fixing. So, what is the main difference - in the emulsion, not the
support - between salted / albuminenized paper and AZO paper? BTW, the
look of AZO prints doesn't resemble even a bit to salted paper and/or
albumenized paper - from what I get from the reproductions of both
mediums.

Thanks in advance,
Loris.
Received on Tue Jan 27 02:11:43 2004