Sigra has a large size rotational viscosimeter which behaves in a hydraulically similar manner to the typical small units. However it has the advantage that it can handle muds or cement grouts containing particulate matter because the gap between the rotating sleeve and the torque measuring bob is greater. Testing can be conducted at a range of temperatures to suit borehole conditions. The results are reported in terms of viscosity versus shear rate and the traditional 300 and 600 rpm viscosimeter readings as well as appropriate constants for Bingham or power law models.