Abstract: The process for measuring viscosity relies on the observation of the relaxation of a sample drop (A) initially flattened between two plates (7,8), normally without any contact with them due to a gas layer blown through their opposite faces (10, 11); one correlates the observed phenomenon with a relaxation model fitting each portion of the measurement curve so as to estimate concurrently the viscosity and the shear rate, then the sensitiveness of the viscosity to the shear rate by compiling the said portions. The proposed viscometer includes a variable magnetic field generator (16) to produce, using a removable screen (18), various stirring and shears in the sample (A).