The first potential root cause that can come from color concentrate is an incompatible material to concentrate problem (keep in mind that there are no “universal carriers”) [1]. This can simply be an issue of using a concentrate that is intended for another material. If, for example, a styrenic concentrate is added to a PP base resin there may be color swirls due to poor intermixing between the materials. Therefore, the appropriate color concentrate should be used with a given base resin.