, how critical is it to not use an acid stop, washing aids, and acid fixers(posted 8893 days ago)Ed, the only time I can say I noticed a real difference is with Technical Pan. When I stopped using an acid bath and switched to F24 (alkaline fixer), I noticed the stain went from, well, barely existent, to a fair amount more present (thought TP doesn't stain greatly in my experience...).