I read a lot of posts wherer people talk about gentle agitation. I don't understand where this comes from. From a mechanical point of view, developer contacts the film, it becomes exhausted. Gentle agitation washes over the laminar layer of exhausted developer and slightly increases its activity. A rapid violent agitation will strip away the laminar layer of exhausted developer and contact the emulsion with fresh developer. I HAVE NEVER HAD STREAKS using this kind of agitation. That includes a combination of AGFA - KODAK - ILFORD films and D76 - D23 - PMK - Pyrocat - PC-TEA - MYTOL - Di-Xactol -including pushing - pulling and every combination you can think of in all formats from 16mm to 4x5. Intrinsically, the gentle agitation doesn't make sense to me. How is it superior to not want to rip off the laminar flow of exhausted developer in a short violent act? My agitation is - after a water presoak of one minute approx - add developer and do 30 seconds of agitation by (semi) rapid inversions followed by tank (1/4 turn in each direction) spinning - this allows the motion to be in varied directions. I do not try to get the chemical to accelerate such that it will cause overdevelop banding near the spool edges. Just 180 degree motions that allow the air in the tank to burst across the film breaking up pockets of exhausted developer allowing fresh developer to do its job. This is usually 2 complete inversions back and forth with one or two 1/4 turn spins and a tap or two setting it down to break loose any bubbles that may have caught. The whole cycle takes 5 seconds or less - and I do it every 30 seconds - All my times are calibrated for this type of agitation and I get reliable grade 2 for condenser enlarger density ranges. Of course I am not suggesting that my way is the right way or that anyone should do anything different - I am just wondering where the gentle agitation idea comes from.