Kerik Kouklis kerik at kerik.com
Wed Oct 28 15:13:17 UTC 2015

I missed the beginning, so I'm not certain which EDTA they were using. They
only called it EDTA and didn't distinguish between di and tetra.

The presentation was more geared for conservators treating vintage prints
rather than contemporary printers. They did a zillion step tests and
artificially aged them at 70 degrees C and 75% humidity for four weeks (I

The bottom line is, in no case was the iron removed completely. In all
cases XRF showed iron was still present and staining got worse as a result
of the aging process.


On Wed, Oct 28, 2015 at 8:07 AM, Clay Harmon Website via
Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org>

> I couldn't get that livecast thing working for some reason although I use
> WebEx all the time on my computer for work stuff.. Go figure...
> Anyway, did they elaborate at all about using disodium EDTA as an
> alternative to acidifying tetrasodium EDTA with sodium bisulfite? My
> current clearing regimen is a first bath of disodium EDTA - roughly a level
> tablespoon per liter is all I can get to dissolve - followed by two
> Hypoclear baths (sodium sulfite + sodium metabisulfite) plus some tetra
> sodium EDTA to goose the iron clearing ability. That works on almost all
> the papers I use.
> -Clay
> On Oct 28, 2015, at 10:56 AM, bobkiss caribsurf.com via
> Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org>
> wrote:
> >
> > I just watched a live webcast on removing residual Fe compounds from
> existing PT/PD prints. It appears that, for processing of new prints good
> old EDTA with some meta bisulfite will do an excellent job. Removing Fe
> from older prints requires some stronger chems like adding Sodium
> Dithionite to EDTA and other chems but they did not recommend using it for
> clearing new prints.
> >
> > Just a non-chemist's observations.
> >
> > BOB
> > _______________________________________________
> > Alt-photo-process-list | altphotolist.org
> _______________________________________________
> Alt-photo-process-list | altphotolist.org

More information about the Alt-photo-process-list mailing list