A colloid mill is a mechanical device used for reducing the particle size of solids dispersed in a liquid medium or emulsifying liquids with high shear forces. It consists of a rotor and a stator, both of which have highly polished surfaces that come into close proximity during operation. The mill operates on the rotor-stator principle: the rotor spins at high speeds (typically between 2000 and 18000 RPM), creating hydraulic shear stress that disrupts and breaks down the structure of the fluid. Colloid mills find applications in various industries, including pharmaceuticals, cosmetics, paints, food, and more. They are particularly useful for increasing the stability of suspensions and emulsions, as well as reducing the particle size of solids in suspensions.