Sizing Agent Selection for Fine Spun Bast Yarns
Optimal fine bast yarn sizing requires balancing PVA and CMC polymers to achieve eleven percent dry add-on without causing warp brittleness.
Residual Size Content
Chemical Residue
Starch concentration remaining on linen yarn after the desizing stage is quantified as residual size content, which determines whether the warp is clean enough for uniform dye penetration. Chinese export mills test this metric immediately following enzymatic breakdown of the potato starch applied during high speed weaving preparations. Technicians boil extracted yarn samples and measure solid carbohydrates remaining in the wash water through titration.
The resulting value governs the acceptance threshold recorded in the mill export certification document. Mill engineers maintain an internal quality standard that allows slightly higher carbohydrate retention than the strict limit demanded by foreign buyers. Exceeding the buyer tolerance creates hydrophobic barriers that block reactive dye molecules from fixing evenly across the cellulose structure.
Enzyme Efficiency
Washing vats rely on alpha amylase preparations to hydrolyze polymeric starches into soluble sugars before acid rinsing clears the bath. Temperature control within the desizing chamber dictates how effectively enzymes break down the stiff coating protecting flax fibres against loom friction. Operators adjust steam valves because thermal variations stall the catalytic conversion process and leave pockets of unbroken starch behind.
Water circulation velocity determines whether loosened carbohydrate chains wash clear of the yarn bundle or redeposit deeper inside the twist. Insufficient rinsing leaves a film that hardens during subsequent drying cycles and distorts the handle of the finished cloth.
Fibre Quality
Raw flax stalks possess natural pectin and lignin compounds that behave differently from applied starches during wet processing stages. Testers separate applied carbohydrates from native plant constituents by comparing hydrolysed wash water against untreated grey yarn baselines. High residual size content masks the intrinsic lustre of flax fibres and causes irregular coloration during piece dyeing.
Yarn destined for domestic markets undergoes less rigorous starch extraction than yarn woven for export apparel houses. Buyers verify compliance using standard weight loss formulas derived from conditioned dry samples taken from every production lot. Lower carbohydrate counts correlate with higher tensile strength because aggressive washing removes degrading acid residues alongside the size.
Rapier against Air-Jet Sheds for Wet-Spun Linen Warps
Positive rapier insertion handles low-elongation wet-spun linen warps reliably, while air-jets trigger high stop rates, pneumatic costs, and greige faults.