Method of distributing pigments in compression molded products

In a method of compression molding a closure having a base wall and peripheral skirt with internal threads wherein a thermoplastic resin is mixed with additives including a particle pigment additive, a melt is extruded through a nozzle, cut into individual pellets, each pellet is deposited into the cavity of a mold which is then closed to compression mold a closure, the improvement comprising

• adding a blowing agent to the resin prior to extrusion,
• controlling the temperature of said melt containing the pigment additive such that the blowing agent reaches its 150.degree. C. activation temperature just prior to extrusion through the nozzle,
• the amount of blowing agent being sufficient to randomize the particle pigment additive such that gaseous bubbles are formed in the extruded melt in an amount sufficient to substantially reduce blemishes normally occurring in compression molding of resins containing particle pigment additive and in an amount not so great that the gaseous bubbles will not be substantially dissipated from the melt during the compression molding to form the closure.