Additive concentrate and use thereof

An additive composition comprising at least one powdery clarifying and/or nucleating agent for polyolefins, which agent is a powder having a melting point of at least 190° C., in an amount of at least 70 wt. %, based on the weight of the composition, and at least one wax having a viscosity of at least 500 mPa·s, in an amount between 0.5 and 30 wt. %, based on the weight of the composition,

• wherein the viscosity of the wax is determined by DIN 53018 at 140° C. for waxes with a softening point below 140° C., at 170° C. for waxes with a softening point from 140° C. to 170° C., at 190° C. for waxes with a softening point from 170° C. to 190° C. and at 240° C. for waxes with a softening point from 190° C. to 240° C.