[pure-silver] Re: Yellow edges
- From: Ryuji Suzuki <rs@xxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 26 May 2005 03:10:53 -0400 (EDT)
From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
Subject: [pure-silver] Re: Yellow edges
Date: Wed, 25 May 2005 18:27:16 -0700
> Since clearing time is very hard to observe for printing
> paper the residual silver test is the best way of
> determining minimum fixing time.
It is very easy to observe clearing time of printing emulsions if they
are coated on glass plates like lantern plates. Despite my rather
thick coating, cubic silver chlorobromide emulsions (usually 70-80%
Cl) clear in about 10 seconds. One commercial chlorobromide emulsion
coated on polyester film cleared in a matter of 5-8 seconds. Bromide
emulsions take a lot longer.
> The idea is that the sulfite wash aid may remove some incompletely
> fixed reaction products giving a false idea of minimum fixing time.
Sulfite does not remove unfixed silver halide (unless you use time
that is long enough for sulfite to fix by itself), which is detected
by the residual silver test you advocated above.
--
Ryuji Suzuki
"Keep a good head and always carry a light camera."
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