A method of incorporating an additive into a polymer composition includes the step of melt blending a polymer with a dispersion comprising a liquid carrier, an unmodified clay, and an additive. Using the dispersion rather than a polymer-based additive masterbatch saves energy. Like a polymer-based masterbatch, the dispersion provides the additive in a diluted form and therefore preserves the masterbatch's advantages of providing more uniform distribution additive in the plastic and avoiding direct handling of additives in the final compounding step. The dispersion is also described.