A method of fabricating plastic products having a preselected characteristic, comprising preparing a dispersion of at least one additive contributes the preselected characteristic in cottonseed oil; supplying a preselected plastic resin for the product to be fabricated to a process machine having a rotating screw; furnishing the dispersion to the process machine at a position adjacent to threaded portion of the rotating screw; and blending the dispersion and the resin by rotating the screw.