By Norbert Kern, Bühler. Premium inks and functional coatings are nowadays mostly produced using a wet grinding process with agitated bead mills. These units have a rotor that puts many small grinding beads into relative motion with each other to create an effective grinding movement. Due to the constant physical friction between the beads, the particle agglomerates of colour pigment are gently broken up, the primary particles are moistened and then evenly distributed in the grinding medium. Quality requirements for these suspensions have continued to increase significantly in the last few years. For example, printing inks for food ...