--- MARTINM responded...
Why do you have to add a stabilizer?
Well, I may not know much about paper emulsions but
speaking about ultra-fine grain emulsions, you
don't necessarily have to incorporate stabilizers to
prevent fog.
Yes, exactly.
By the way, like Ray, I also wondered about your
method of converting AgCl into AgBr. For spectral
sensitization this might have some interesting side
effects - but for paper emulsions???
Martain,
Converted emulsions are reported to have been popular for
paper emulsions at one time.
They are supposedly easily developed but suffer from
certain defects such as increased risk of excessive
pressure sensitivity.
Conversion is usually very rapid, and can be done quite
easily in a convienient procedure, as you already know.
I think what I felt was somewhat misleading was Ryuji's
claim that no finished emulsion is succeptable to
conversion... I don't think this is an accurate assesment
of the facts, despite what may appear to be experimental
evidence to the contrary...(I may have more to say on this
after reviewing the articles cited elsewhere).
Core/shell emulsions, for example (also called covered
grain emulsions), were discoverd at Kodak by analysis of
certain emulsions that exhibited speed variation during
coating... these emulsions (again suppossedly optimally
stabilized) were found to be undergoing very mild Ostwald
Ripening... the result being that the sensitivity centers
were being coverd up, changing the nature of the emulsion
from a surface image emulsion to an internal image
emulsion.
Ray
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Received on Wed Dec 1 05:54:23 2004
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