There are a lot of variables in film processing that are out of the control of film manufacturers. When your thermometer says 68 degrees is it really 68 degrees or is it the same temperature as my thermometer that might read 72 degrees. When you mixed 50ml or stock solution with 450ml of water did you get it right? Or was it really 60ml and 440ml water? Are you pushing or pulling the film? That changes the speed of the film. Do you agitate 5 seconds every 30seconds or 5 every 60? How vigorously? There are many more variables that I'm sure will be added below, but I think you can see that there is no one answer.(posted 8290 days ago)RICARDO