Rheometry measures the flow and deformation of materials in response to applied stress and strain to evaluate their viscoelastic properties. It is used to evaluate the mechanical behavior of samples with both liquid- and solid-like characteristics.

In a rheometry test, a sample is subject to shearing with preset speed, frequency and temperature conditions –which can be either static or dynamic. Subsequent rheological changes in the material’s viscosity alter the amount of torque required to maintain a consistent shear speed and frequency, and thus the time-dependency of applied torque during measurement provides insight into the rheological nature of the material. In complex fluids and semi-solids, this encompasses time- and temperature-dependent non-Newtonian behaviors, such as: shear thinning and thickening, viscoelasticity, and gelation, among others.