A continuous-filament yam that has been processed to introduce durable crimps, coils, loops or other fine distortions along the lengths of the filaments.
Note 1: The main texturing procedures which are usually applied to continuous-filament yarns made from or containing thermoplastic fibres, are:
(a) the yarn is highly twisted, heat-set and untwisted either as a process of three separate stages (now obsolescent) or as a continuous process (false-twist texturing). In an infrequently used alternative method, two yarns are continuously folded together, heat-set, then separated by unfolding;
(b) the yam is injected into a heated stuffer box either by feed rollers or through a plasticizing jet of hot fluid (invariably air or steam). The jet process is sometimes known as jet texturing, hot-air jet texturing, or steam-jet texturing;
(c) the yam is plasticized by passage through a jet of hot fluid and is impacted on to a cooling surface (impact texturing);
(d) the heated yam is passed over a knife-edge (edge crimping), (now obsolete);
(e) the heated yarn is passed between a pair of gear wheels or through some similar device (gear crimping);
(f) the yam is knitted into a fabric that is heat-set and then unravelled (knit-deknit texturing);
(g) the yam is over-fed through a turbulent air stream (air-texturing, air-jet texturing), so that entangled loops are formed in the filaments;
(h) the yarn is composed of bicomponent fibres and is subjected to a hot and/or wet process whereby differential shrinkage occurs.
Note 2: Procedures (a) and (d) in Note I above gives yams of a generally high-stretch character. This is frequently reduced by re-heating the yam in a state where it is only partly relaxed from the fully extended condition, thus producing a stabilized yarn with the bulkiness little reduced but with a much reduced retractive power.
Note 3: The procedure (g) may also be applied to fibres which are not thermoplastic.
Textile Resource (http://www.textile.org.uk)