as EVA or LDPE can be used as carriers for polyolefins and nylon, polystyrene can be used for ABS, SAN, and sometimes polycarbonates. When a carrier different than the base plastic is used, the carrier material may modify the resulting plastic's properties; in which case the carrier resin has to be specified. The usual ratio of masterbatch to base resin is 1-5%. Several masterbatches (color and various additives) can be used together. The carrier can also double as a plasticizer (common for liquid masterbatches) or a processing aid. The machines are usually fed with premixed granules of the host polymer and the masterbatch. The final mixing then gets done in the screw and extrusion part of the machine. This is sometimes prone to adverse effects, like the separation of the masterbatch and the base material in the machine's hopper. The masterbatch can be also added directly to the machine's screw, as a free-flowing solid or, if the masterbatch is liquid, by a peristaltic pump. Such use of liquid masterbatches allows highly accurate dosing and quick change of color between machine runs. Masterbatches can be used in most processes, except rotational molding and Plastisol and other liquid resin systems. Masterbatch production Masterbatches are produced in accordance with the required standards in the plastics industry and, if provided, to customer specifications. The general process for the manufacture of masterbatches involves the following steps: the identification and weighing of the required pigments and/or additives, the mixing of these pigments and/or additives into a carrier resin or polymer by heat treatment and twin-screw extrusion, the cooling and forming of the concentrated mixture into granules, powders, and other masterbatch vehicles, and the bagging of the final product. Advantages of using masterbatches in plastic manufacturing Masterbatch brings some physical property improvements for the final plastic products: Productivity Masterbatch can increase volumetric output (as a result of thermal conductivity & volumetric expansion to temperature). In addition, it has ability to downgauge due to higher film physical properties. Cost reduction With the large percentage of CaCO3 powder in component, Masterbatch helps manufacturers reduce material cost by using less energy to run the machine due to higher CaCO3 specific heat Masterbatch helps plastics to improve many physical properties such as, Toughness Flexural stiffness Adhesion Printability It can also be used for applications where varying levels of permanent electrical conductivity are required for use in applications where accumulation of static