A method of producing pigmented extrudates or mouldings from an unpigmented thermosetting moulding material, which comprises roughly blending a pigment component with an aminoplast moulding material substantially free from pigment and having an average particle size not greater than 150 microns, and completely dispersing the pigment compound through the aminoplast moulding material by progressing the rough blend through an extruder or injection moulding machine having a barrel grooved in accordance with German Offenlegungschrift No. 2514307, and extruding or injection moulding the resulting pigmented material.
Apparatus including a barrel including a generally cylindrical inner wall defining a generally cylindrical chamber having a longitudinal axis, an inlet end for receiving solid material, and an outlet end for discharging molten material, the inner wall having therein a recess extending longitudinally of the chamber, a screw which extends along the longitudinal axis and which is rotatably housed in the chamber, a drive mechanism for rotating the screw about the axis, and a conduit for introducing colorant into the chamber, the conduit having a downstream end communicating directly with the recess so that colorant flowing through the conduit flows directly into the recess.
