Quote Originally Posted by brimc76
Thanks Brian. I read that it stopped some kind of oxidation that seemed to give RC prints a metallic look in some of the shadow areas (?). This change is suppose to happen if you place the print in a frame and it is under glass.
I remember an article by Ctein in one of the "Techniques" magazines to that effect. While I have a tremendous amount of respect for Ctein, I squinted my eyes reading that one. Seemed *far* more complicated - and less understandable - than what he usually writes.

I've been using RC papers since there were RC papers ... and have quite a few framed, under glass ... except for a few that were insufficiently fixed (I dumbly believed the manufacturer's recommendation for 30 seconds of rapid -ammonium thiosulfate - fixing) - I've seen nothing like a "metallic" shift, with or without toning or "Sistan".

I have used Sistan for the last ... ??? ten (?) years. One minute in a tray of - I've got to check the recommendations again - was it 25ml / liter?

*No* change in appearance - none that I can see. The treated prints - from 'way back, with and without glass - are fine.