RE: Silver chloride contact printing papers - AZO

I was trying to illustrate the "amplifying" effect of development, as
opposed to what happens with printing-out papers where there is no
amplification. In that context what I state is not inaccurate.

DF

-----Original Message-----
From: Ryuji Suzuki [mailto:rs@silvergrain.org]
Sent: Tuesday, January 27, 2004 1:49 PM
To: alt-photo-process-l@sask.usask.ca
Subject: Re: Silver chloride contact printing papers - AZO

From: David Foy <dfoy@privateaddress.net>
Subject: RE: Silver chloride contact printing papers - AZO
Date: Mon, 26 Jan 2004 15:48:18 -0700

> 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.

AgX crystals are comparable in size to developed grains, and the
silver to form filaments is coming from the interstitial silver ions
within the AgX crystals. If you subject the material to physical
development, the grains will look more like balls rather than
rolled-up filaments. My guess is that you are confused between silver
halide crystals and latent image silver specks. Silver specks can be
as small as a few silver atoms on surface or in deep area of the
crystal. Specks are amplifed during development by a huge factor to
make optically visible mass of metallic silver from silver ions
supplied from crystals they are connected to, or from the solution in
the case of physical development. Physical development would make
bigger spherical or similar shaped grains.

--
Ryuji Suzuki
"Reality has always had too many heads." (Bob Dylan, Cold Irons Bound, 1997)