In 1996 Ilford told me, in a phone conversation about the quantity required to develop sheet film, that 2.5ml of Ilfosol-S concentrate was required to develop one square inch of 100 Delta. They recommended that I use 3 ml/sq inch for safety. I have been doing so with no problems. I recently called Ilford and asked the same question about DDX and could not get an answer.(posted 8316 days ago)