The separation of mixed plastics by resin type and/or colour via a mechanical system. A system detects the plastic type (or types) to be segregated and removes those materials from the stream. Common systems utilise conveyors, resin/color detectors, computer analysis and tracking and air jet ejectors. For plastic packaging, the separation may be on a macro (whole container) or micro (chopped/ground particles) basis. ("Automatic Sorting for Mixed Plastics," Peter Dinger, BioCycle, March 1992; "Automatic Microsorting for Mixed Plastics," Peter Dinger, BioCycle, April 1992).