Compound, masterbatch & filler
Compound
Compounding is a process used to mix fillers, additives, colour pigments or different polymers or grades of polymers. This process normally consists of dry blending, melting in a single or twin-screw extruder, filtering, homogenising, forming of a strand and pelletising.  Compounds are used to obtain good and consistent quality.

Masterbatch
A masterbatch is a concentrated mixture of additives, i.e. colour pigments, in a carrier polymer. A masterbatch is often used instead of a compound to decrease costs, where small volumes are required. However, the consistency may not be as good as with a compound.