Re: What is green ?

Jeffrey D. Mathias ()
Tue, 14 January 1997 7:29 PM

Eric J. Neilsen wrote:
>
> Jeff and Philippe,
> When I make my ferric oxalate as per the Dick Stevens receipe in The
> Difinitive Guide to Making Kallitypes it is a bright emerald green. I have
> also made B&S ferric achieve this bright color by adding additional
> oxalic acid and 30% hydrogren peroxide. Richard's Ferric has a tendency
> to be a bit yellow/brown/green. It works great with a little help.
>

Eric,

I add 1 gram oxalic acid to 50 ml ferric oxalate solution GLSmyth@ari.net (27%) and
somtimes use hydrogen peroxide as a contrast agent. However, I have not
observed the solution to be a "bright emerald green". What is meant by
"a little help"? I would appriciate if you would please send your
formula.

Also, what do you mean by 30% hydrogren peroxide. The type purchased
from a drug store is typically 3%. 30% can be purchased from a chemical
supplier, but caution must be used since it is a combustion and
explosion hazard. Did you mean that to 20 ml ferric oxalate you add 10
ml of 3% hydrogren peroxide ? If so this would seem to be far too much
contrast for a properly processed negative for the Pt/Pd process. But
maybe not.

Jeff

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