Liam Lawless (lawless@vignette.freeserve.co.uk)
Mon, 25 Jan 1999 00:06:28 +0000
Hi,
Re. your comments on Sandy's bleach, isn't Cl available from the
hydrochloric acid? If Br is added as well, wouldn't one of them be
redundant? If the Br does something that Cl does not do, have you any idea
what it might be?
Appreciate your help,
Liam
-----Original Message-----
From: Sil Horwitz <silh@iag.net>
To: alt-photo-process-l@sask.usask.ca <alt-photo-process-l@sask.usask.ca>
Date: 24 January 1999 23:33
Subject: Re: Pyro redevelopment
>At 10:11 AM 1999/01/24 -0400, Sandy King wrote:
>
>>>This still doesn't explain Sandy's results. As a matter of interest,
Sandy,
>>>why is there bromide in your bleach?
>>
>>Quite frankly I don't know exactly what the bromide does but it is
>>recommended in the formula of several super proportional reducers that I
>>have on hand. I am going to assume that its primary function is to
restrain
>>the heavier silver deposits and reduce overall density, but this is only
>>speculation.
>
>In most bleaches, there is an oxidizer to produce a reactive silver ion,
>and a receptor (like bromide) to combine with the ion immediately to form
>silver halide (silver bromide if there are bromide ions present). Silver
>halides, of course, can then either be dissolved in fixer, or made to
>further react with another substance (as is done in toning).
>
>Sil Horwitz, FPSA
>Technical Editor, PSA Journal
>silh@iag.net
>Visit http://www.psa-photo.org/
>Personal page: http://www.iag.net/~silh/
>
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