ISO 2061:2010 specifies a method for the determination of the direction of twist in yarns, the amount of twist, in terms of turns per unit length, and the change in length on untwisting, by the direct counting method
ISO 2061:2010 is applicable to
- single yarns (spun and filament),
- plied yarns, and
- cabled yarns.
Separate procedures are given for each type of yarn. The method is designed primarily for yarns in packages, but, with special precautions, the procedures can be used for yarns taken from fabrics. It is not suitable for the determination of twist in a monofilament.
ISO 2061:2010 covers the determination of twist in plied and cabled yarns as follows:
- in plied yarns: the final twist of the plied yarns and the original twist of the single yarn before plying;
- in cabled yarns:
- the final cabling twist of the yarn;
- the original twist of the plied yarn after plying, but prior to the last stage of processing;
- the twist of the single yarn before plying.