Polyester Spun yarn is a term that refers to yarns that are produced from chopped fibers. Because these yarns are not uniform, they cause better air circulation in clothes and more comfort. Spun yarns are usually single or multi-ply with: Scores (10,12,16,30,40,50) are used and produced by ring and open-end spinning systems. Spun yarn is used in raw and colored form by the weavers of round weaves, flat weavers and sock weavers.