I'd like to add the following: FX37 1:5 21 C 6.5 minutes constant agitation with Jobo Expert drum. Zone I density EI 500= 0.11, EI 400= 0.15 instead of 160 with Pyrocat-HD. I measure FX37 negatives with a Heiland TRD2 densitometer. Pyrocat negatives tests have been done with standard printing time method. I hope this helps. Bulent Ozgoren