A colloid mill is a machine that is used to reduce the particle size of a solid in suspension in a liquid, or to reduce the droplet size of a liquid suspended in another liquid. Colloid mills work on the rotor-stator principle: a rotor turns at high speeds (1500 - 2800 RPM[1]). The resulting high levels of hydraulic shearapplied to the process liquid disrupt structures in the fluid. Colloid mills are frequently used to increase the stability of suspensions and emulsions, but can also be used to reduce the particle size of solids in suspensions[1]. Higher shear rates lead to smaller droplets, down to approximately 10-30µm[2] which are more resistant to emulsion separation.