Near Infrared Multi Spectral Occlusion Limits in Dense Raw Cotton Tuft Streams
Dense cotton tufts block near infrared light past three millimeters, hiding synthetic contaminants beneath opaque cellulose surface layers during optical sorting.
ISO 10306
Dimensional Stability
Cotton yarn shrinks during wet processing because natural cellulosic fibres swell radially and contract longitudinally under moisture release. ISO 10306 specifies the test method for determining the shrinkage of twisted single and plied yarns obtained from packages, governing the commercial acceptance of commercial yarn lots before dyeing and knitting operations begin. Yarn testing laboratories measure skein length variation after soaking and drying under specified tension to verify that commercial deliveries match buyer specifications, stopping at the point where yarn is converted into a woven fabric structure.
Water Immersion
Skeins are wound on a reel under a predetermined pretension derived from the linear density of the yarn sample. Immersion in water at room temperature for a designated duration allows the twisted structure to relieve internal stresses stored during the spinning process. Free drying on hanging racks follows the soaking phase without applied loads, ensuring that length recovery proceeds strictly from internal relaxation mechanics rather than external stretching forces.
Length Measurement
Initial and final lengths are determined by measuring the circumference of the skein under standard atmospheric conditions before and after the wetting cycle. Calculating the percentage difference provides the numerical value for dimensional change in length per unit mass. Commercial contracts rely on this calculated percentage to establish whether a yarn lot falls within acceptable contraction limits for apparel manufacturing.
Tension Control
Pretension weights applied during winding dictate the baseline geometry of the test skein and prevent slack loops from distorting the initial measurement. Variations in applied load alter the final percentage outcome significantly, making precise mass calibration mandatory for every test batch. Strict adherence to specified conditioning parameters ensures that mill laboratories produce repeatable shrinkage data for commercial settlements.