Polyethylene
Polyethylene is the most common plastic in the world and a versatile synthetic polymer. In cosmetics, it appears in two main forms: as microbeads (now banned in many jurisdictions under legislation such as the U.S. Microbead-Free Waters Act of 2015) and as a white wax. In its wax form, it is used to thicken water-free formulas, increase hardness, and raise the melting point of emulsions and waterless balms.
In wax form, polyethylene adds body, hardness, and slip to formulas such as cleansing balms and stick-type makeup products. It functions primarily as a texture and viscosity modifier rather than providing direct skin-care benefits.
Polyethylene microbeads are banned in rinse-off cosmetics in several countries due to environmental accumulation in waterways; the wax form is not subject to these bans and remains in common use.
