From: Peter Marshall (petermarshall@cix.co.uk)
Date: 10/04/01-03:18:26 AM Z
> I wanted to report back to the list that copper sulfate does
> absolutely
> NOT work in the process. Luckily I had the copper chloride solution
> mixed
> and enough to tide me over with 2 sections of lab, but I had mixed the
> same
> formula, substituting copper sulfate at the same strength of copper
> chloride
> (30g) with the acetic acid 80 ml and the water 1000 ml and the hydrogen
> peroxide 40 v at equal parts, and no go.
I used to do this with classes using copper sulphate years ago without any
problems, so it is a matter of getting the formula and conditions right.
You can't just substitute the copper sulphate for the chloride, but need
to find a formulation using the sulphate. I suspect I may have used either
some hydrochloric acid and/or sodium chloride as you almost certainly need
both copper and chloride ions. I'm pretty sure I didn't use acetic acid.
Finding my old notes is likely to be a problem, but I think it is in the
archive. The recipe I used was from a magazine article published in the
1970s which I probably threw out years back.
The other bleach you mention contains bromide ions - which do the same job
as the chloride ions in the bleaching process.
Peter Marshall
Photography Guide at About http://photography.about.com/
email: photography.guide@about.com
_________________________________________________________________
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Also on Fixing Shadows: http://www.people.virginia.edu/~ds8s
and elsewhere......
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