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.
Slub Count
Frequency Quantification
Numerical tallying of abrupt, short mass increases per unit length quantifies optical profile defects in spun flax yarns. Recorded during yarn clearing or woven fabric inspection in linen manufacturing mills, slub count measures thick places exceeding standard yarn diameter thresholds over short distances. Laboratory test sheets and automatic clearer logs report the number of slub events per one hundred thousand meters of yarn or per hundred square meters of woven cloth.
Slubs originate from accumulated fly or raw flax bark fragments remaining in the sliver. The metric records discrete short thick places while ignoring long term yarn count variations.
Optical Counting
High speed optical sensors on automatic yarn winders monitor yarn cross-sectional profile during rewinding operations. The sensor compares instantaneous yarn diameter against baseline yarn count, triggering cutting blades when a slub exceeds set thickness and length thresholds. Unwanted slubs are cut out and replaced with automatic splices to ensure smooth weaving performance.
Settings balance cut frequency against winder efficiency to prevent excessive yarn joinings.
Contract Limit
Purchasing yarn specifications set maximum permissible slub counts based on intended fabric application. Premium fabric specifications restrict slubs to under five per hundred thousand meters, while rustic linen specifications allow higher counts to retain natural texture.