[alt-photo] Re: dilution of pt/pd - pH of EDTA

[EJ Photo]

The pH of your solution may change with addition of different versions of
EDTA. Addition of EDTA would depend on source of FO, I do not add it to my
solutions which are made directly to liquid. It might be required to get
your pH to a happy place for your FO powder to get into solution by using
oxalic acid, the EDTA after may simply be an additive that works for some
and not others based on paper being used.  

Eric Neilsen
Eric Neilsen Photography
4101 Commerce Street, Suite 9
Dallas, TX 75226
 
www.ericneilsenphotography.com
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Let's Talk Photography
 

-----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: Saturday, July 24, 2010 6:36 AM
To: The alternative photographic processes mailing list
Subject: [alt-photo] Re: dilution of pt/pd

Clay which EDTA is that? I presume Na2EDTA... Right?

2010/7/24 Clay Harmon Website <clayh at clayharmon.com>:
> Mark, adding oxalic acid to the FO will shorten the exposure time. I
tested this years ago, and it is increases the light sensitivity of
> the coating solution. And slightly increases its exposure scale. And makes
it easier to clear. No downside to adding it that I was
> ever able to detect. My formula is 27g FO, 4g oxalic acid, 2g EDTA to make
100ml. I think this is a pretty standard mix.
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