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

[clay at clayharmon.com]

I agree. Disodium EDTA is the acidic version of EDTA. Tetrasodium is basic and and is just not a good idea all by itself.
On Dec 30, 2011, at 6:40 PM, etienne garbaux wrote:

> Mark wrote:
> 
>> For all you Platinum/Palladium Printers, I am curious what your current practice is for clearing platinum/palladium prints.
>> I use primarily Palladium with the Na2 method for contrast or I use straight palladium.
>> 
>> For clearing I use 3 baths of Heico Permawash dilute 1 ounce per quart.  5 Minutes in each bath, then every couple of prints I dump the first bath and rotate with freshest bath last.
> 
> I would never trust any Pt/Pd clearing process that did not begin with a reasonably strong acid (my preference is hydrochloric acid at 1% or so) followed by a 10 minute rinse, pH neutralizing (2-3 minutes in a weak sodium sulfite solution -- you can use diluted commercial silver-gelatin wash aids for this), and a good long wash.
> 
> Some folks use iron sequestering agents these days rather than acid, but to the extent that there are insoluble iron compounds deposited in the paper (and there always will be), you really need the acid bath to solubilize them.
> 
> AFAIK, Permawash is just a typical silver-gelatin wash aid -- an alkaline solution of sulfites and sulfates, perhaps with some silver and calcium sequestering agents.  If it contains any iron sequestering agents, it is only by accident -- it was not formulated for iron processes.
> 
> Best regards,
> 
> etienne
> 
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> 
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