[alt-photo] Re: Stoichiometry for the nonscientist

[C.Breukel at lumc.nl]

> -----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 Loris
> Medici
> Sent: dinsdag 3 augustus 2010 16:16
> To: 'The alternative photographic processes mailing list'
> Subject: [alt-photo] Re: Stoichiometry for the nonscientist
> 
> Thanks for the clarification Eric. So it's more common to use a
slightly
> acid developer then...



In my limited experience when printing pure platinum on Simili Japon and
developing in PotOX; to keep the developer alive (you'll see that the
developer is off immediately: you get these very ugly measles),

Aside of keeping the volume constant by adding fresh PotOx and
filtering:

Keep the developer around pH 5 by adding pure Oxalic Acid. When the
developer goes off the pH reaches a pH of 7 or so. 

When you apply this method the developer keeps very long, and does not
have to be tossed out like I did by mistake the first time....

Best,

Cor

Btw I also sun my developer to get rid of the Pt salts in solution (I
assume that the (UV) light reduces these) and filter of the black
precipitate..I always keep this filtrate, one day I promised to my self
to make Pt2Cl6 (if that is the correct formula, notes at home)


> From: alt-photo-process-list-bounces at lists.altphotolist.org On Behalf
Of
> EJ
> Photo
> Sent: Tuesday, August 03, 2010 4:42 PM
> To: 'The alternative photographic processes mailing list'
> Subject: [alt-photo] Re: Stoichiometry for the nonscientist
> 
> ...
> As far as where to stop with the mixing, I do not agree with Loris
that
> many
> go to pH7 with this. I keep my solution slightly acid, around pH5 and
> allow
> for a little excess oxalic acid to help keep it that way after several
> sheets of buffered papers is run through it.
> ...
> 
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