Textile Glossary: Yarns

The raw material for yarn comes in one of two forms: filaments or staple fibers.

1. Filaments

A filament is a fine fiber long enough to form a single yarn on its own.

Silk is the only natural filament. It is obtained by unraveling the cocoon of the mulberry silkworm Bombyx mori, which can be as long as 700 to 1,200 meters.

The other filaments are all of artificial or synthetic origin. They are obtained through a process called extrusion, and they are unlimited in length.

Prior to spinning : filaments can be texturized, introducing a bit of a crimp, which lends a fuller appearance, more coverage and elasticity.

2. Staple fibers

These are filamentary materials of various lengths, which must be combined into strands to form a yarn.

Cotton, wool and bast fibers (linen, hemp, etc.) are all staple fibers, as are silk schappe and noil, known as bourrette silk (derived from broken filaments, pierced cocoons, etc.)

Artificial and synthetic fibers can also be cut into staple fibers. This option makes it easier to create blends with natural fibers.

Prior to spinning : After removing impurities (for natural fibers), staple fibers are homogenized in a lap and then carded. Carding involves untangling and aligning the fibers, by compressing them into a carded sliver. At this stage, combing can be done, to separate short fibers from long ones.

Short fibers are typically used for carded spinning, which produces low-density, puffy yarns.

Long fibers are generally used for worsted spinning, which aligns the fibers and produces regular, fine, strong yarns.

Spinning processes

The main spinning processes for staple fibers are:

  •  Ring spinning (or continuous spinning): The card sliver is gradually stretched and twisted to form a roving*. This roving is again stretched, twisted and wound through a ring. This process produces very fine, strong yarns, with occasional irregularities.
  • Compact spinning is a variant of ring spinning that produces yarns with high tenacity and reduced hairiness.
  • Open-end spinning: The card sliver fibers are sucked into a turbine and centrifugally transformed into yarns at an accelerated rate. These yarns are thicker and more uniform than those produced by ring spinning.
  • Air-jet spinning involves directing fibers through a nozzle without twisting them. The spun yarn is obtained by winding the outer fibers around the inner fibers, which remain parallel to the axis. This type of open-end spinning is quicker, but produces yarns that aren’t as strong.

* Each fiber has its own characteristics, and the tools involved in processing them are different for cotton, wool, linen, etc. All these tools (gills, roving frames, etc.) have the same goal: to assemble staple fibers into increasingly fine rovings. This article is not intended to go into detail about this, which is why we have simplified our discussion.

Yarn construction

There are three types of construction:

  • Throwing involves applying a more or less strong twist, in S or Z direction, to strands or yarns.
  • Single yarns (described above) aremade up of several strands twisted together.
  • Plied yarns are composed of several single yarns twisted together (generally in opposite directions, but all configurations exist and influence the stability, neatness and the tendency to untwist). Twisting increases a yarn’s strength and regularity.
  • Cable yarns are made up of several ply yarns, with at least one ply twisted together.

The twist density, calculated in turns per meter, affects the characteristics of the yarn:

A low twist creates a puffy, supple yarn with good coverage. A high twist lends strength and rigidity to the yarn, which tightens and has a drier handle. A crepe twist is a twist so strong that the yarn contracts in length, forming small undulations (crepe = crinkled) that give the yarn mechanical elasticity, with a grainy, dry handle. (This crepe twist is only achievable with relatively long fibers).

  • Covering consists in winding a filament or spun fiber around a fixed core. This type of construction has a wide variety of applications, including elastic yarns and those used for dévoré techniques, for example.
  • Fantasy yarns generally comprise a single yarn, an effect yarn and a binder yarn. Examples of fancy yarns include chenille yarns (or velvet yarns), loop yarns, snarl yarns and sequined yarns, among others.

Yarn count

The yarn count refers to the fineness of the yarn, calculated in a weight/length ratio.

  • Tex is the universal unit of measurement and indicates the weight in grams of 1000 meters of yarn.
  • Denier indicates the weight in grams of 9000 meters of yarn. This unit applies to filaments.
  • Metric count (Nm) indicates the number of kilometers per kilogram of yarn. This unit applies to spun yarns.
  • New English Count (Ne) indicates the number of hanks in a pound (453.6 gr).

From yarn to fabric:

Slubbed fabric: composed of slubbed yarns (featuring elongated, irregular bumps).

Crepe: fabric made of crepe-twist yarns (Note: by extension, fabrics whose weave lends them a characteristic grainy appearance are called “crepe”, but only those having crepe-twist yarns will have its characteristic drape).

Lamé: fabric containing “lames”, flat metallo-plastic filaments with a metallic appearance.

Chiné: fabric composed of spun yarns made from two (or more) different colors spun together.

Tweed: fabric made from “tweedy” yarns (irregular in color and diameter: chiné, knopped, chenille, slubbed, or fancy thrown yarns and more).

Bouclette: fabric with loop yarns.

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