A coarse-particle plastics granulate is colored by being dosed and mixed with a fine-powder pigment by means of a dosaging screw and, if necessary, an after-mixer at the discharge end of said screw. A coarse-particle "cleaning material" is supplied to the dosaging screw upstream of the pigment to prevent sticking and caking of the fine powder and to achieve uniform distribution of the color in the granulate. A proportion of the granulate itself may be introduced as the cleaning material. The dosaging screw is mounted so as to be readily replaceable by a clean one. It may be formed with two sections of different diameter so that the entry volume at the cleaning material inlet is smaller than at the pigment inlet. The dosaging screw is normally driven in time with a plastics processing machine using the colored granulate, but may be adapted to operate discontinuously when only a small amount of color is required or when the machine output is small.
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