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From: petermarshall@cix.compulink.co.uk (Peter Marshall)
Date: Fri, 28 Jun 96 18:06 BST-1
Subject: Re: amidol and Evans
In-Reply-To: <v01540b02adf854aac159@206.101.78.61>
Maxim
> This is a cannard that has been recently published in the
> photographic press by one of your countrymen. Amidol works in an acid
> condition as a reducing agent when the pH is very much lower than what
> is encountered in a typical stopbath (about pH 2.4-2.7) In an acid
> bath above this range (4.5-5.5 of most stopbaths) it barely reduces at
> all. pH 6.8 and below will slow it down to a crawl. The often heard > > remark "it works in an acid condition" needs to be qualified-yes it
> will, but only if the solution is REALLY acid. I would suppose few
> darkroom practioneers would choose to use HCL or sulfuric acid as an
> accelerator for amidol. A citric acid stopbath will satisfactorily
> work with prints developed in amidol.
Thanks for this correction Maxim, although it seems to contradict almost
all what has previously been published on the use of amidol- from round
about its first use - and not just a single reference as you suggest.
Not that this surprises me as much received wisdom is at least partly
false.
I understood when I used it that the citric acid bath is generally
suggested not because it acts as a stop bath but to prevent the pink
staining of prints which can occur when using amidol. It is certainly
satisfactory but I never thought when I used it that it was acting as a
stop bath. (I always assumed that amidol print development was more or
less to completion in any case - so didn't need stop.)
Stop baths are not actually necessary for most materials in any case. I
haven't used one with film for many years.
I used to use amidol as a print dev regularly for several years, but
eventually decided I could get just as good results with a more normal
developer that came in cheap 5 litre packs (from May and Baker who went
out of business years ago.) Perhaps when that disappeared I should have
tried amidol again, but I'd got used to the convenience of just using
stuff 1+9 out of the bottle.
Peter Marshall
Fixing Shadows and elsewhere:
http://faraday.clas.virginia.edu/cgi-uva/cgiwrap/~ds8s/Niepce/peter-m.cgi