Re: Clearing of Iron Salts in Pt/Pd paper

Richard Sullivan (richsul@roadrunner.com)
Thu, 13 Nov 1997 08:42:27 -0700

I did some experiments years ago, maybe a decade or more. The best clearing
bath I found was some stuff used to remove rust stains from spas. There a
re a variety of them available at pool supply and hardware stores. They all
seem to work well. Presumably safe as well, as you are expected to also
steep in the spa along with the stuff. Cleans ferric oxalate stains off of
your bippy too.

Another powerful clearing agent is Eagle Mag Wheel cleaner from Pep Boys.
It appears, believe this!, to be dilute hydrofluoric acid, like with an
"F". Lime Away works well, mostly phosophoric acid, with a ton of
peppermint smelly in it that will drive you to drink. Most restaurant
supply companies sell a thing called bar glass cleaner which seems to have
a ton of edta and other goodies in it. Getting calcium scum off the glasses
is critical, customers will think they are dirty and spoils the look of the
drink or brew. Anything that removes calcium will remove iron, they are
first cousins to each other. 7-Up works well too, mostly phosophoric and
citric acids with a little sugar and flavoring.

Dick Sullivan

At 04:22 AM 11/13/97 -0500, you wrote:
>Message text written by Stephen R Harrison
>>(5) I very definitely have trouble using only EDTA as a clearing
>agent no matter how many baths I use? Anyone use only EDTA to clear pt/pd
>prints? For which papers?<
>
>I experimented with various clearing baths when it became clear that 1 %
>HCl softened the image. Citric acid was tried as a weaker acid but the
>amount needed made the process logistically inconvenient. Following Mike
>Ware's support of EDTA as clearing agent for his ammonia based approach to
>Pt/Pd printing, I tried EDTA as the clearing agent for prints made using
>the traditional method on Fabriano Artistico and Saunders Waterford. It
>certainly seemed to work well but after five years I am beginning to notice
>a slight yellowing on some prints. I am assuming that I had not been so
>assiduous as I should have been in limiting the number of prints going
>through the baths. I have not yet tried reclearing those prints but is
>there any reason why they should not clear ? Given that the main
>constituent of KODAK hypo clearing agent is EDTA is there another
>ingredient that is making it so effective as a final bath or might one be
>better off just using another EDTA bath ?
>
>Terry King
>
>
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