[pure-silver] Re: Pyro in a Jobo Processor
- From: "John Black" <jblack@xxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 18 Mar 2005 11:15:30 -0500
> >
> My understanding is that EDTA holds metallic salts like
> Magnesium carbonate in suspension. Parhaps it has some
> effect on oxidation products of developers also. Sodium
> sulfite preferentially absorbs oxygen to prevent is
> oxidising the developing agents. Sulfite has several
> functions in developer but this is a principal one.
> Rotary processors use rather small amounts of developer
> in thin layers, a condition guranteed to cause aerial
> oxidation. Pyro developers appear to be particularly
> vulnerable to aerial oxidation although they are also
> supposed to be fairly good about not causing aerial fog. It
> seems to me that Pyro developers are just not a good choice
> for drum type processors.
>
Interestingly enough, many years ago, I used to do anaerobic bacterial
culture in glass dessicator jars that used pyrogalol converted to pyrogalic
acid (I think) to provide anaerobic conditions. All I remember is that we
used a innocuous looking white crystalline material and added some acid to
it to make a black, tarry looking material that stank horribly but it would
suck all of the oxygen from the air pocket in short order. That particular
form of pyro was an O2 magnet.
I've not used pyro as a developer, does it have an unpleasant odor?
JB
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