[pure-silver] Sulfite stabilization
- From: "John Black" <jblack@xxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 5 May 2005 16:12:22 -0400
Some of you may remember that I am engaged in a developer component
stability with time test using phenidone, ascorbic acid, tris buffer and
sulfite. This study was undertaken out of sloth because I want to be able
to make up film and paper developer and fixer out of stable liquids when I
need them, not powders. I have stabilized the PC and buffer to my
satisfaction with no loss in potency over a years' storage but I have been
recently tried several methods of sulfite solution preservation.
My favorite formula contains some, but not much sulfite. About 5-6 gm/L but
it is necessary for the level of activity I need. Well, to cut to the
chase, I found that the more concentrated the sulfite solution is, the
better it keeps (surprise, surprise!) so I started using saturated NaSulfite
solutions (about 26-27%) as additive. I am up to 4 months now and see no
loss of sulfite reactivity (reduction potential) from the saturated solution
as compared with freshly made solution from powder. I measure the activity
densitometrically (did I spell that right?) with a procedure of my own
design. I am hoping to get a years' stability at this level out of this
solution also.
Unfortunately, this means I must have a solution C as well as A and B to mix
with water but that's not so bad. These solutions can be mixed in different
ratios and with other things to make film developer, paper developer,
fixative and hypo eliminator. A dash or two of saturate sulfite solution
works wonders to freshen up a tired fixer batch that is about used up. All
this of course is using glass bottles with good seals.
More later.
JB
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