Had a great time learning a thing or 999 about producing mezzotint plates with the master, Guy Langevin. He had a very physical approach, almost like a martial art or sport. He corrected my posture and my technique very thoroughly, making me aware of how the position of my body would affect the outcomes both of the rocker and the wiping of the plate. What a great example of the physicality of printmaking! Your balance and technique must be mathematically precise and careful at all stages of the execution of a mezzotint like Guy's.