Determining Bast Fibre Linear Density by Air Permeability Methods
Air permeability testing measures specific surface area to derive bast fibre linear density, requiring precise moisture conditioning and shive removal.
Specimen Parallelization
Fibre Preparation
Processing flax straw into spinning readiness requires mechanical sorting where specimen parallelization aligns individual strands within a drafting frame before rove production begins. Natural bast fibers arrive at the combing floor in tangled bundles containing varied staple lengths and residual woody shives. Technicians feed these raw bunches through intersecting gill boxes featuring moving pin bars that pull the stubborn clumps straight.
Aligned ribbon emerges from the final delivery rollers carrying minimal twist and uniform linear density across every linear meter. Mill superintendents record these measurements inside the daily batch ledger to verify draft regularity before the material moves toward the wet spinning frames.
Drafting Control
Tension variations during drawing operations alter yarn strength parameters if sliver uniformity drifts outside accepted mill tolerances. Automated sensors mounted above the consolidation rollers measure linear weight fluctuation and adjust the drawing speed dynamically to compensate for thick spots. Heavy segments receive greater draft ratios to stretch the fiber mass thin while light regions experience reduced attenuation.
Operators cross-check these machine logs against the master buyer specification sheet to confirm that the finished yarn meets commercial standards for tensile resistance and elongation at break.
Yarn Acceptance
Final quality verification depends upon laboratory testing where extracted yarn samples undergo breaking length determinations under standardized atmospheric conditions. Evaluators clamp single strands into dynamometers and apply constant strain until rupture occurs, recording the exact force required for failure. Cloth manufacturers reject lots displaying high variance in breaking tenacity because uneven yarn creates weak zones across the woven warp face.
Fabric grade classifications depend directly upon these laboratory values rather than visual appearance alone.