How Flax Fibre Is Graded into Linen Yarn
Flax fibre grading determines spinnable yarn count, where hackling yield and fibre fineness dictate wet-spinning efficiency and landed cost per metre.
CV Percent
Variability Measure
Statistical variance relative to mean mass per unit length defines the standard measure of irregularity in spun flax yarns. An electronic capacitance sensor measures mass variation across a moving strand, expressing this relative standard deviation as cv percent. In flax spinning mills, testing laboratory certificates record this value alongside yarn count to establish mass uniformity across slivers and spun yarns.
Standard testing protocols specify a sample length of four hundred meters run at controlled relative humidity. Value thresholds shift between wet spun long line yarns and dry spun tow yarns due to inherent differences in short fibre distribution. The metric applies strictly to mass fluctuations over short distances and excludes long term pattern shifts from bobbin build cycles.
Tester Signal
Capacitive sensors evaluate the yarn dielectric constant to detect mass changes along the strand length. Optical sensors operate in parallel on dark flax fibers to prevent optical artifacts from flax shive particles. High readings indicate periodic defects introduced by draft roller eccentricity, broken faller pins, or uneven drafting apron pressure.
Mass peaks registered during testing correspond to thick places and thin regions, which alter yarn strength during subsequent weaving operations. Laboratory reports separate periodic variations from random fiber clustering by plotting a spectrograph alongside the numerical result.
Yarn Tolerance
Buyer purchase specifications for Chinese linen mills establish strict acceptance ceilings for yarn irregularity. Premium wet spun yarns for apparel warp applications mandate limits below fourteen percent, while coarser dry spun yarns accept higher variance up to twenty-two percent. A lot exceeding the contract threshold faces downgrade or price renegotiation before fabric formation.