Statistical Metric
A statistical measure of yarn evenness tracks the variations in weight per unit length along a spun strand of flax. The mass irregularity cv represents the percentage coefficient of variation in these mass measurements as recorded by a capacitance-based evenness tester. High values of this metric indicate a yarn with frequent alternating thick and thin regions that will compromise subsequent processing.
This quantitative calculation provides spinning mills with a standardized method to compare yarn quality across different production runs and spindle batches. It provides a basis for classifying yarn grades before export.
Spinning Influence
Drafting rollers in the spinning frame must control the movement of short flax fibres to prevent drafting waves. When the mass irregularity cv increases, it suggests that the draft ratio is incorrect or that the roving has been stretched unevenly. Mechanical maintenance of the aprons and rollers is necessary to keep this variability within acceptable tolerances.
Fabric Appearance
Finished linen fabrics made from highly uneven yarns exhibit a patchy surface with irregular light transmission. Since the mass irregularity cv remains constant through winding, these imperfections are carried directly into the loom process and produce visible bands or streaks in the finished cloth. Buyers often reject linen shipments that exceed the agreed threshold for this variance.
