Yarn Count and Sizing Chemistry in Warp Preparation
Warp sizing requires matching yarn packing factor to polymer viscosity, adjusting squeeze nip pressure for precise solids add-on, and maintaining elongation.
Zweiweg Hairiness Index
Measurement Scale
Numerical rating that quantifies the number and length of protruding fibres on a yarn’s surface provides a standardized measure of yarn hairiness. Testing laboratories use the Zweiweg hairiness index to evaluate the suitability of wet-spun flax yarns for high-speed loom operations. This metric calculates the total length of all protruding fibres within a given unit length of yarn.
Its value helps spinners optimize the spinning and winding parameters.
Optical Sensor
An optical sensor measures the light scattered by the yarn’s main core and its protruding fibres as the strand passes through the test zone at a constant speed. The zweiweg hairiness index represents the ratio of this scattered light to the total light transmitted, providing a comprehensive assessment of the yarn’s surface texture. Flax yarns tend to have higher indices than cotton due to the coarse nature of the bast fibres.
Spinning mills use these index reports to adjust the suction pressure on compact spinning frames and the tension on winders. This sensor technology replaces subjective manual inspections with precise digital data.
Quality Standard
Cloth mills specify a maximum index value in their purchase contracts to avoid purchasing brittle yarn. Compliance with this threshold reduces warp breaks during shedding. Accurate measurements ensure yarn consistency across different batches.