[alt-photo] Re: Question for Platinum/Palladium printers

[Denny]

I'm using 3% citric acid for 5 minutes followed by HCA with Stonehenge and
it seems to be working.  I mask the negs for white borders and the borders
look clear.  Is there a more definitive test for residual iron that should
be used?     

-----Original Message-----
From: alt-photo-process-list-bounces at lists.altphotolist.org
[mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of
etienne garbaux
Sent: Friday, December 30, 2011 4:07 PM
To: The alternative photographic processes mailing list
Subject: [alt-photo] Re: Question for Platinum/Palladium printers

Clay wrote:

>I agree. Disodium EDTA is the acidic version of EDTA. Tetrasodium is 
>basic and and is just not a good idea all by itself.

I have not tested it, but I doubt the acidity of Disodium EDTA is sufficient
to solubilize stubborn iron complexes.  I think you need a "mineral" acid
(i.e., not organic) for that -- for example, acetic and citric acids are not
enough (in my testing citric acid gave a valiant effort, and perhaps if you
let prints soak for an hour it would work reliably, but I do not consider it
trustworthy for this duty).

Best regards,

etienne




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