</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (David A. Goldfarb @ Oct 19 2002, 07:13 AM)</td></tr><tr><td id='QUOTE'>You&#39;re probably seeing a combination of carryover and reduction of stain.

Disparagements regarding the current faddishness of alkaline fixers notwithstanding, I would just note that if you switch to an alkaline fixer, you won&#39;t need to worry about overfixing or reduction of stain in the fixer.</td></tr></table><span id='postcolor'>
Why? I understand the alkalinity will prevent reduction of stain. But the overfixing I dont understand why not. What are the components of alkaline fixers? If I recall my chemistry correctly it is necessary to form sodium argentothiosulfates for easy removal. Hypo made of sodium thiosulfate made this possible, many people added ammonium chloride to speed the reaction and then the switch was made to ammonium thiosulfate for "rapid fixers". I suspect alkaline fixers are made of alkaly thiocyanates but in the end double silver salts have to be formed for removal thus the possibility of overfixing.