[pure-silver] Re: Seasoning a developer - cream without sediment
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sun, 7 Feb 2010 07:11:54 -0800
----- Original Message -----
From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Saturday, February 06, 2010 1:42 PM
Subject: [pure-silver] Re: Seasoning a developer - cream
without sediment
----- Original Message -----
From: "Nicholas O. Lindan" <nolindan@xxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, February 05, 2010 8:57 PM
Subject: [pure-silver] Re: Seasoning a developer - cream
without sediment
"Nicholas O. Lindan" <nolindan@xxxxxxxxxxxxx>
There was a method of getting to this point with a fresh
batch of developer
by 'seasoning' it.
Should have done some research before posting.
There are several discussions on this topic in the google
groups archives
for rec.photo.darkroom, search for <seasoned developer>
It seems the seasoned effect is due to a build up of
bromide and silver.
The bromide buildup can be achieved by adding .7 g/l of
P. Bromide
to D-76, don't know what the amount would be with Xtol.
Don't know
about the silver salts - is there some way to get them
out of used
hypo?
==
Nicholas O. Lindan
Cleveland Engineering Design, LLC
Cleveland, Ohio 44121
For B&W developers its mostly bromide, I am not sure
what else is in "developer starters" for color. Some of
the residue in replenished developers is gelatin from the
film. Some may be precipitated minerals from the water.
The developer should be filtered occasionally to prevent
deposits of junk on the film. A coffee filter or a wad of
cotton in a funnel works fine.
Very large developing plants, like motion picture
labs, recover silver from all solutions by electrolytic
means. This is both to recycle the silver and to extend
the life of the solutions. The methods are covered in the
technical literature but I no longer remember specific
detail. Electrolytic regeneration of hypo seem to me to go
back a very long time.
In color work virtually all the silver in the emulsion
is removed during processing to the amount that can be
recovered is considerable and generally is worth enough to
pay for the recovery. Note that at large labs the
processing solutions also undergo continuous chemical
analysis as part of keeping the processing consistent.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
Having read this later...
The old idea of seasoning is to add some used developer
to fresh stock. Whatever accumulates in the developer is
then carried over in some small amount. AFAIK, there is no
fixed rule for this. It makes sense for continuous machines
or replenished systems. The seasoning will affect the film
curve somewhat and of course will reduce film speed just a
bit. However, it may also reduce grain a bit too.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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