Ever notice that fuzzy halo on the surface of your favorite knit sweater? The fuzzy ends that you see are the result of abrasion and friction. Poor abrasion resistance causes fiber ends and fiber debris to break away from the surface and entangle with fibers still attached to the material, leading to formation of pills.
Pilling is affected by the type of fiber, the twist of the yarn, the knit or weave structure, and the finish of a fabric. Tightly knitted stretch fabrics pill much less than loose knits or weaves. Spun fibers such as cotton or wool are also known to pill. Having a filament yarn such a spandex in your stretch knit fabric can increase abrasion resistance and decrease pilling, keeping your active wear knit fabrics in perfect condition.
(1992). A dictionary of textile terms. (14 ed.). New York, NY:Dan River, Inc.