Due to small order quantity, I used colour pigment ( powder form ) on PS frame retardent grade base for the injection moulding process. A strange occurrence is that colour tone changes from light colour to dark colour and than back to light colour again. It happened each time with same batch of material in the hopper. The colour is never even although with constant barrel temperature,constant temperature controller etc, What causes this phenomenon and can any members advise from this ?
Thanks & Regards