Capillary ripples are damped both by sub-surface viscosity and by surface rheology. Fumed silica is commonly used as a rheology agent to make otherwise low-viscous fluids thixotropic. The rheology of nanocellulose dispersions has been investigated. The study of extensional flows is called extensional rheology. Blood is a non-Newtonian fluid, best studied using rheology rather than hydrodynamics. Granular rheology refers to the continuum mechanical description of granular materials. The rheology of guar gum is typical for a random coil polymer. Metal soaps are also included in modern artists' oil paints formulations as a rheology modifier. Xanthan gum provides great "low end" rheology. The field of rheology presents an overlap between solid and fluid mechanics. The team works on rheology, complex fluids and interface management. Thus, the observations of postglacial rebound provide a natural experiment to measure mantle rheology. It is used as a rheology modifier. It measures the rheology of the fluid. The ability of ringwoodite to incorporate hydroxide is important because of its effect on rheology.