in a recycling process , granulated plastic material coated with a paint film is melted in an extruder . during extrusion , the paint film is volatilized and removed by vacuum from the melted granulate stream . additives are admixed with the particulates and any remaining paint film in an extruder . water is introduced into the melted plastic stream in the extruder to neutralize toxic material levels discharged from the extruder and from the extruded plastic material .