Textiles - Unevenness of textile strands - Capacitance method (ISO 16549:2004, IDT)
This International Standard describes a method, using capacitance measuring equipment, for determining the unevenness of linear density along the length of textile strands.
The method is applicable to tops, slivers, rovings, spun yarns and continuous filament yarns, made from either natural or man-made fibres, in the range of 4 tex (g/km) to 80 ktex (kg/km) for staple-fibre strands and 1 tex (g/km) to 600 tex (g/km) for continuous-filament yarns. It is not applicable to fancy yarns or to strands composed fully or partly of conductive materials such as metals; the latter require an optical sensor (see A.4).
The method describes the preparation of a variance-length curve, as well as the determination of periodicities of linear density. It covers also the counting of imperfections in the yarn, namely of neps and of thick and thin places.
Irregularities in the distribution of additives such as sizes, in moisture content and in fibre blending may increase the measured unevenness above its true value.