Nothing special about citric acid; just, if it ain't broke, don't fix it
See the section below, taken from Mike Ware's Argyrotype article BTW:
"...Without exception all the iron-silver processes to date have used the most commonly available soluble salt of the metal, namely silver nitrate. But nitrate is an oxidising anion, and tends to dissolve the colloidal image silver during wet processing, *especially under acidic conditions*. To minimise this loss of image the Kallitype process employs alkaline-buffered developers of high pH, e.g. Borax. Alas, these create a new problem, because they cause hydrolysis of the excess iron(III) in the sensitizer and the deposition of insoluble ferric hydroxide in the image, which ultimately causes it to fade..." (Emphasis mine...)
Last edited by Loris Medici; 01-04-2012 at 02:35 AM. Click to view previous post history.
Reason: Added P.S.