In the Ilford product data guide (1998 edition) Ilfotec HC (1+31) is recommended for best overall quality when developing 100 Delta and 400 Delta and for maximum sharpness with 100 Delta.(posted 8499 days ago)I understand that Ilfotec HC is very similar to (if not identical to) Kodak HC-110, a developer I have used for some time with good results using HP5+ and Tri-X.
Has anyone had good results using HC-110 with 100 and/or 400 Delta (either new or old versions)?