Yarn Definition List

From Fiber to Yarn: What Spinning Does

Every woven or knitted fabric starts one step earlier, as yarn, and every yarn starts one step earlier still, as fiber. Fibers - cotton, wool, flax, silk or manufactured fibers such as polyester and nylon - are short or continuous strands that on their own are too fine and too weak to make cloth. Spinning draws those fibers out and twists them together so they lock into a continuous strand with usable strength. The amount of twist matters: a low-twist yarn is soft and lofty, suited to knitting, while a high-twist yarn is smoother, harder and stronger, suited to weaving warps that must survive tension on a loom. Ply adds another level of structure: two or more single yarns twisted together make a plied yarn, balancing the strand and reducing the tendency of a single yarn to curl or untwist.

Yarn size is described by count systems rather than by simple thickness, because a yarn is bought and sold by weight and length. Indirect systems such as cotton count and worsted count rise as the yarn gets finer; direct systems such as denier and tex rise as it gets heavier. A specification that names the fiber, the spinning system, the ply and the count tells a mill almost everything it needs to reproduce a yarn, which is why these definition pages matter in practice: buyer, spinner and weaver have to mean exactly the same thing by the same word.

Spun Yarn, Filament Yarn and Thread

Spun yarns are made from staple fibers - fibers of limited length that are carded, combed in finer qualities, drawn out and twisted. Filament yarns take the opposite route: a manufactured fiber is extruded as one or more continuous filaments, which may be used smooth and flat, textured for bulk and stretch, or cut into staple and spun like a natural fiber. Sewing thread is yarn engineered for a narrower job. It must be smooth enough to pass through a needle and fabric thousands of times without fraying, strong enough to hold a seam under stress, and finished so it does not twist or snarl while sewing, by hand or by machine.

The three spinning machines linked from this list mark the long mechanisation of that work. The spinning wheel put one spindle under the control of a single spinner, turned by hand or treadle. The spinning jenny, invented by James Hargreaves in the 1760s, let one operator work many spindles at once - first eight, and in later versions far more - multiplying output without changing the basic drawing-and-twisting action. The spinning frame, developed from Richard Arkwright's water frame patented in 1769, used rollers to draw the fibers and produced a stronger, more even yarn suited to warp threads, and it belonged in a powered factory rather than a cottage. Modern ring spinning and open-end (rotor) spinning are the direct descendants of those machines, and the definitions here give the vocabulary for all of them.

Choosing and Using Yarn

In use, yarn is chosen by matching fiber, structure and count to the end product. Knitting yarns favour softness, elasticity and bulk, so the fabric can form loops and recover; weaving yarns divide into warp yarns, which need strength and abrasion resistance, and weft yarns, which can be softer and more decorative. Embroidery yarns and threads are made for surface effect - lustre, colourfastness and smooth passage through a ground fabric - while crochet uses yarns much like knitting yarns, worked with a hook instead of needles. Hand knitters meet yarn sorted by weight names from lace and fingering through worsted to bulky; industrial buyers meet the same range expressed in counts and deniers instead.

Care follows fiber more than structure: wool yarns can felt under heat and agitation, cotton yarns tolerate washing well but may shrink, and manufactured fibers can be sensitive to high ironing temperatures. Whatever the end use, the chain on this page - fiber, yarn, fabric - is the order of manufacture, and the linked fiber and fabric definitions complete the sequence that the yarn definitions begin.