Rotor Speed Changing RPM has the largest single effect on mix time. A 5 RPM increase can reduce mix times up to 10%. In mixing trials, incrementally raise RPM, stopping before the point in which it is too fast for good black incorporation & dispersion. For example, if 50 RPM yields a good mix but 60 does not, then attempt RPM’s in between. The optimum RPM to produce a quality product in the most efficient time may be 54 or 56. Choosing the optimum RPM may be more efficient and uniform than changing RPM’s during the mix phase