Re: Pyro and staining

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From: Christina Z. Anderson (tracez@mcn.net)
Date: 06/29/01-10:55:08 AM Z


Hi Brian!
The acid supposedly reduces the stain, but does not PREVENT the stain.
However, with the alkaline afterbath in the developer and the return to
normal PH in the water rinse, the stain increases. I used to use the TF4
fixer, but now I just use the Kodak rapid fix without hardener, then water
stop, and the developer afterbath and I get plenty of stain. That was after
Richard Knoppow was so sure that the TF4 alkaline fixer would not be good
archivally, if I remember correctly on the pure silver list.
Chris

> I'm curious about the conflict between the statement here, to the effect
> that an acid stop bath or fix will prevent the pyro stain from forming,
and
> the instructions n Gordon Hutchings' book to the effect that an acid stop
> bath is fine with normal development. Based on Hutchings' book, when
using
> PMK pyro I've used an acid stop bath and fix and haven't noticed any
> problems with a stain forming as long as the film is immersed in the used
> developer for two minutes and washed for 20-30 minutes. Would I get a
> "better" stain if I switched to water in place of the stop bath and to a
> non-acidic fix? If so, in what way would it be "better?"
>
> I know that I could switch to a non-acidic fix and eliminate the used
> developer step but that step isn't particularly difficult or time
consuming
> and I'd rather continue with it than add yet another chemical (non-acidic
> fix) to my darkroom unless there's a good reason to do so.
>
>
> ----- Original Message -----
> From: "Carl Weese" <cweese@earthlink.net>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Monday, June 25, 2001 6:41 AM
> Subject: Re: Pyro and staining
>
>
> > Pyro stain is allergic to acid conditions -- an acid stop bath or fix
will
> > prevent stain formation on regular silver gelatin film...
> >
> > >
> > > From what I have read the pyro will not oxidize very rapidly in an
> acidic
> > > solution. How much time do I have to use it before it starts to
degrade?
> The
> > > reason I ask is that I am adding Pyro to each "shot" of developer vs
> mixing
> > > up a batch. Batching is more convenient.
> > >
>
>


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