Studies were carried out on coating glass beads with. ne hematite particles by use of the theta composer, a newly developed high-shearing-type mixer. Topics of study included the effects of rotational speed of the rotor, N-r, (i.e., tangential velocity of the rotor tip, v(r)), and a gap width between the rotor and the wall of the vessel, l, on the coating process. The amount of hematite particles deposited on glass beads was plotted versus a parameter epsilon(=v(r)(2)t/l) that relates a cumulative shear force acting on particles over a coating period t. All experimental data could be fitted by a single curve, and the parameter e was found to describe the coating process in the theta composer. Compression of core particles by the rotor was also analyzed using a 3-D DEM simulation. Average contact force by the rotor was found to be proportional to v(r) and inversely proportional to l. Thus, a cumulative shear force acting on a core particle is proportional to (v(r)/l)(v(r)t) after the particle passes through the gap N(r)t times. Reasonable agreement was found between the experimental results and those of simulation. The coating process can be properly described by the parameter e.