Charles Steinmetz (csteinmetz@redneck.efga.org)
Wed, 03 Mar 1999 02:15:25 +0000
Following some unwarranted sniping at Rae, let me confirm that there are a
zillion variables that WILL foil anyone's chances of simply following an
emulsion recipe and getting the same result as the author. To name four
very quickly:
(1) Gelatin. All gelatins are different, and will react differently both
physically and chemically with the forming halide crystals.
(2) Reactant jets. Silver nitrate, sometimes the soluble halide(s), and
sometimes other reactants are injected into the stirred gelatin solution
through orifices that create jets of the reactant solution(s). No two
fixtures will produce identical jets, and even if they could, the
relationships between the jets in the swirling gelatin solution wouldn't
be exactly the same.
(3) Stirring. No two fixtures will produce the same flow dynamic.
(4) Temperature, and temperature profile. Most formulas involve changing
the temperature and holding it for a determined time, several times. The
instantaneous temperature profile will almost never be the same.
Best regards,
Charles (preparing for the time when silver-gelatin is alt)
This archive was generated by hypermail 2.0b3 on Sat Nov 06 1999 - 10:06:54