Platinum printers: dark stains on prints?

I realize there are alt process forums for Pt/Pd questions, but have found the turnaround a bit slow, and there do seem to be some Alt process types lurking around here, so, without further apology:

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I developed, cleared and washed a 12X20 Pt/Pd print using my usual technique (K Oxalate developer at 100 F, three 5 minute washes with phosphoric acid, 3 liters in each, the last wash 100% freshly made up solution, followed by a 20-30 min wash.) The print has dirty gray stains, looking sort of like somebody walked over the print with dirty shoes. They're most visible along the white edge of the paper (It's Platinotype, by the way), but also in a few sections of the lighter sky. Only some areas are affected. The print otherwise looks fine. Couldn't find this described in the Arentz or Sullivan/Weese books. Any thoughts? I'd like to avoid another expensive mistake!

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Thanks as always,

Nathan

Did you use a different cutter to cut the paper to size than you've

used before? New roller wheel? Something else that is allowing

microscopic steel residue to be left behind?

Nathan,

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Did you notice any "bleeding" from the black borders of the print

during development? When there's too much of this the particles can

deposit in the print or the border as stain--a sort of mechanical fog.

Stains that are grey are either some sort of fog or unwanted deposit

of partially cleared metal. Yellow or orange stains would be from lack

of adequate clearing.

The culprit might be your phosphoric acid, maybe is exhausted already

and not clearing your prints totally, get some litmus paper and check

it's pH...anything above 4 or 5 and you are probably using an

exhausted clearing agent.

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Good luck.

Looking over the print, I think Carl is probably right, though I'm

not clear why I am getting this bleeding now. As mentioned above,

the last phosphoric bath is 100% freshly made solution 3 L, so I

don't think the clearing is inadequate.

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Thanks for your thoughts!

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Nathan

Now that you have the problem solved, I note that you are using the

Oxalate acid route to processing. I realize this is the traditional

process, but have you considered going with more modern (and less

dangerous) materials?