Warp Preparation and Sizing Standards for Wet Spun Linen Yarns
Optimal wet spun linen weaving requires low viscosity binder penetration, pneumatic water splices, and eight percent size pickup to maintain loom shed efficiency.
Size Retrogradation
Chemical Aging
Structural aging in cooked starch solutions occurs when gelatinized polymer molecules align and form insoluble crystalline aggregates. In linen mills, size retrogradation happens when the cooked sizing liquid is allowed to cool down or sit undisturbed for too long. This molecular realignment turns the smooth starch gel into a thick, rubbery substance that cannot easily penetrate the flax yarn fibers.
Technical sheets dictate that the sizing liquor must be prepared and used within a specific time window to avoid this degradation.
Rheology Impact
The altered state of the adhesive leads to poor film formation and uneven coating of the flax yarn. Size retrogradation decreases the starch’s binding ability, resulting in a crumbly surface layer that flakes off when the warp yarn is under tension. If this old size is applied, the flax fibers do not get the protection they need, which leads to high hairiness and increased thread breaks during weaving.
Operators can detect this problem by observing a sudden increase in starch residue inside the sizing machine’s feed pipes.
Viscosity Preservation
Maintaining the sizing bath above sixty degrees Celsius and keeping the liquid constantly agitated prevents this unwanted recrystallization. To avoid size retrogradation, mills use jacketed storage tanks that maintain a steady temperature and utilize continuous stirring mechanisms. Technicians monitor the sizing liquor’s viscosity and record these values in the daily preparation logs to ensure the mix remains in its fluid, active state.
This careful process management prevents the waste of starch materials and ensures that the warp yarns are always coated with high-quality adhesive. Maintaining a clean system also reduces the time required for flushing the lines during weekly maintenance, which helps the mill run at higher overall efficiency and keep production schedules on track.