Ryuji,
Why you feel commercial emulsions are more likely to be
composed of bromoiodide rather than chlorobromide?
Which emulsions are you basing this conjecture on?
In response to your previous mail... (where you seem to be
claiming that one will inherently have greater coating
difficulties on watercolor paper with a chlorobromide
emulsion than a bromoiodide emulsion because the former is
more fastidious, due differences in the solubility of the
isolated halides...)
I seriously doubt any differences in solubility of the
silver halides could have the least bit of effect upon the
system under discussion. (We are talking about trouble
hand coating AgX-Gelatin emulsions on semi- verses fully-
sized paper.) I have hand coated most combinations (AgCl,
AgClBr, AgBrCl, AgBr, and AgBrI) and have experienced no
trouble, at least nothing related to specfic halde
compsition.
What kind of trouble did you discover?
Whatever it was, I am quite sure identical results would
occur with a plain gelatin solution (were it light
sensitive) in the absence of any silver halide.
True, you have not described what actually happened, so
there is little more that can be said.
I would like to say again that you did not identify which
emulsions, what information or what "hunch" you are basing
your conjecture that commercial bottled emulsions are
typically bromoiodide, upon.
For the record, I examined four different emulsions
(excluding all of those I had prepared myself), and one
commercial emulsion designed for B/W prints that was not
ment to be released in bottled form.
There were significant differences, but none of those
differences support your position.
You wrote:
>Chlorobromide emulsions are a lot more fastidious.
I had to look up your word fastidious...
1. Giving and careful attention to detail; hard to please;
excessively concerned with cleanliness....
2. Having complicated nutritional requirements....
I'm confused.
Why do you say chlorobromide emulsions are a lot more
fastidious?
In what way are they more fastidious?
Ray
-----------------------------------------------------> >
Since we are discussing coating trouble on paper
> with
> > different degrees of sizing, I do not understand
> why you
> > felt it necessary to discuss the halides actually
> used
> > liquid emulsions (AgClBr or Ag BrI) The precise
> halide
> > content is totally irrelevant, but since you did
> bring it
> > up: WHY?
> It is very relevant. AgCl and AgBr have an important
> difference in
> their Ag-AgX electrode potential. They also have
> different ksp values
> and different ranges of pAg they often operate at.
> These differences
> give rise to different reactivity or susceptibility
> to a lot of
> things, including reactions when the emulsion comes
> in contact with
> watercolor paper. Chlorobromide emulsions are a lot
> more fastidious.
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Received on Wed Dec 29 07:35:04 2004
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