Abstract: The present invention comprises a method of comminuting/pulverizing polyurethane-containing materials to produce fine particles. The method of comminuting/pulverizing polyurethane-containing materials comprises first chopping the polyurethane-containing materials, thereby producing a polyurethane-containing flock. The polyurethane-containing flock is then processed to form a powder through a comminuting/pulverizing process wherein the comminuting/pulverizing process has at least two steps. Finally, a solid additive is added at any time during the comminuting/pulverizing process to prevent adherence of the polyurethane-containing materials powder during one of the at least two steps.