Twist and carpet durability
Yarn twist, particularly in cut-pile carpet is important to performance. Carpet appearance will deteriorate as un-twisting of the yarns occurs. Therefore, yarns with higher twist rates (a tighter twist on the individual yarn) will retain their original appearance longer. Heat setting of the yarn also helps in retaining twist and appearance. Today, almost all yarns used in cut-pile carpets are continuous heatset yarns.