The only developing agent that will last even an hour without an inhibitor
like sulfite is Amidol, and that's not particularly good for films nor for
big grain. If you want to minimize the edge effect provided by normal
developers that are loaded with sulfite, make up something like a D72 with,
say, 1% of the sulfite and use it once (you will find it is almost black at
the finish of development due to oxidation of the developing agent in the
absence of sulfite).
Sil Horwitz, FPSA
Technical Editor, PSA Journal
silh@iag.net