Clay Harmon Website clay at clayharmon.com
Wed Oct 28 15:07:29 UTC 2015

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.

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 
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