Colorants change the look of the plastic to the human eye. With the help of light, the colored plastic will take on white, yellow, green, blue, red, black, or any other hue. Colorants affect the properties of a formulation. They come with their own properties, such as weather resistance, light-fastness, and transparency, along with FDA approval and more. Colorant suppliers have developed products specifically for different plastic applications and for use with different polymer types. Testing follows international standards and provides good information about the suitability of specific products for specific applications.
In principle, all pigments containing substantial traces of metals such as ionic copper, iron, and manganese, can impair, both thermal stability during processing, and aging resistance in service. Suitable tests are indicated depending on the intended application for the end use application. Free metal ions in manganese lakes, for example the once widely used C.I.