RE: Pt./Pd. question acid pre-soak

Before the test can be done, you need a standard FO.

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> -----Original Message-----
> From: Ryuji Suzuki [mailto:rs@silvergrain.org]
> Sent: Monday, August 08, 2005 9:59 PM
> To: alt-photo-process-l@sask.usask.ca
> Subject: Re: Pt./Pd. question acid pre-soak
>
> I don't do platinum/palladium printing so I can't answer the question,
> but if anyone is to do the test, I suggest for the comparison part to
> use unbuffered mineral acid in a controlled amount to maintain the
> target pH, if you want the results to be interpretable. Oxalic acid is
> a dicarboxylic acid, which can be involved in reactions with metal
> ions. In particular, oxalic acid makes a soluble compound with ferric
> ion. Citric acid is more active in similar reactions with a wider
> range of metals, and it's not a good comparison target for this
> purpose. Citric acid having more carboxyl groups as well as having one
> carboxyl group attached to the same carbon as the hydroxyl group makes
> it very reactive with metal ions. Though not ideal, acetic acid is ok
> for the comparison in spite of its carboxyl group.
>
>
> From: Sandy King <sanking@clemson.edu>
> Subject: Pt./Pd. question acid pre-soak
> Date: Mon, 08 Aug 2005 20:37:03 -0400
>
> > As we know a pre-soak in a 1-2% solution of oxalic acid can add quite
> > a bit of Dmax in Pt./Pd. printing with some papers. Does anyone know
> > the mechanism of how this works? Is it merely a question of
> > acidifying the paper? Has anyone ever compared the results between
> > papers pre-soaked in oxalic acid and in some other dilute acid
> > solution, say a 1-2% solution of citric acid?
> >
> >
> >
> >
> > Sandy
> >
Received on Mon Aug 8 23:25:55 2005