ABSTRACT
This chapter discusses Yarn nomenclature and the factors that influence yarn properties. The textile industry has built a terminology that is dependent upon the nature of the fiber, yarn, or fabric, the country where the nomenclature developed, and the period in history during which common usage was established. The yarn "number" or "count" defines the relationship between yarn weight and length. Twist is necessary in order to manufacture staple fiber yarns and to give integrity, compactness, snag and abrasion resistance to filament yarns as well as to cords and ropes. Trade practice uses a relatively simple code for identifying count, yarn twist, and twist direction. For indirect yarn numbers, the count of the singles yarn is given, followed by the number of singles combined to make the plied yarn, and the number of plied yarns combined to make the cord. Certain classical mathematical relationships can be derived and are useful with respect to yarn manufacture.
