Jack Fulton (jfulton@itsa.ucsf.edu)
Wed, 03 Nov 1999 07:41:21 -0800
As I had understood this Ag sensitivity training stuff … when the lads first
made prints in old blighty (England), the use of salt w/silver was the norm,
hence, chloride.
This was slow.
Then it was bromine, hence, Kodabromide.
Lastly iodine was incorporated and ultimately an admix, hence, iodide was the
speediest, themost sensitive.
POP would be too quick if it used the Io and Bro mides.
As I remember (from my halcyon daze) one could purchase what was called
'contact' paper. This was chloride based.
As an aside, for years I was mixed up when contact paper was introduced as
kitchen shelf paper w/a sticky back to "hold it firmly in place."
Jack
Liam Lawless wrote:
> Hi Sil,
>
> You may be right that silver iodide is more sensitive to light than the
> bromide, in which case I'd be grateful for more information (or sources).
> But what you say is counter to my experience, and, I see in Cassell's
> Cyclopaedia (Turneretscher's Table of Sensitivenesses, etc., p. 490), that
> silver bromide was thought to be considerably more sensitive than iodide in
> all circumstances (i.e. with excess of salt or silver, with/without ammonia
> fuming). And, if iodide is more sensitive, why does it find no use in POP
> emulsions, or only in tiny amounts in develop-out silver-gelatin emulsions?
> While it was widely used in the very earliest silver processes, wasn't it
> mostly replaced with bromide and/or chloride later on, because of their
> greater sensitivity?
>
> Liam
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