Four Point Inspection Procedures for Woven Linen Greige Cloth Quality Control
Standardized four-point greige inspection prevents downstream finishing losses by enforcing objective ASTM D5430 defect scoring before cloth conversion.
Slubs and Neps
Yarn Irregularity
Thickened yarn segments and tightly tangled fibre clusters represent inherent structural characteristics of spun flax. Spinning mills monitor slubs and neps during yarn clearance to separate natural linen texture from unwanted spinning defects. Controlling the frequency and size of these variations determines yarn grade and aesthetic classification.
Formation Mechanism
Inadequate flax retting and incomplete mechanical hackling leave coarse fibre bundles intact, which gather into thick slubs during wet or dry spinning operations. Neps form when fine immature flax fibres roll into tight spherical knots under friction against card clothing or drafting aprons. Electronic yarn clearers on automatic winders detect these high-mass anomalies and activate optical cutters to splice out severe imperfections before beam winding.
Adjustable clearer channels allow mills to retain desirable natural slubs characteristic of traditional linen while removing tight neps that cause needle breakage during garment assembly.
Finishing Impact
Chemical bleaching, mercerizing, and dyeing alter how thick yarn regions absorb liquid chemicals compared to smooth yarn sections. Heavy slubs and neps obstruct dye liquor penetration, producing pale cores that expose raw un-dyed bast fibre when friction abrades the fabric surface during laundering. Shearing and singeing processes burn away protruding surface neps, yet embedded thick slubs remain integral components of the fabric structure.
Quality control laboratories measure nep counts per gram of carded sliver and slub frequencies per kilometer of yarn to certify yarn consistency for export customers.