Single-filament crimp within a carpet tuft is its geometric feature most responsible for body in cut-pile saxony carpet. Yam twist within the tuft is most responsible for imparting wear. Crimp setting factors can be manipulated to influence either the amount of crimp or its permanence, but not without consequences: factors impacting crimp permanence, like increased energy or dwell time within the crimper, can also impact a carpet's wearability by influencing the amount of twist that can be set. At moderate levels of inserted twist. carpet wear is inversely dependent on crimp permanence: the greater that permanence, the poorer the twist is set and the worse the resultant carpet's wear. The concepts of crimp and twist permanence and their interaction are introduced, and a method for quantifying that permanence is provided.