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.
Size Bath Viscosity
Fluid Flow Property
Liquid resistance to flow measured within the sizing delivery tank governs the amount of protective solids absorbed by the yarn. Maintaining the correct size bath viscosity ensures that the sizing liquor penetrates the yarn core while leaving an adequate coating on the surface. This variable is sensitive to temperature changes and the concentration of starch or synthetic polymers in the mix.
Process Control
Continuous monitoring of the liquid flow behavior prevents fluctuations in size pick-up and yarn performance. When the size bath viscosity rises too high, the liquor cannot penetrate the dense flax yarn, resulting in a thick, brittle surface layer that flakes off during loom operations. Conversely, if the viscosity is too low, the sizing penetrates too deeply, leaving the yarn surface unprotected against abrasion.
Operators must use automated viscosity controllers or manual cup tests to measure and adjust the concentration of the sizing mix. This careful control ensures a consistent film thickness on every yarn batch.
Fabric Quality
Uniform sizing application leads to consistent mechanical properties across the warp sheet, which reduces yarn breakages. Stable size bath viscosity prevents variations in fabric weight and stiffness across different production batches. This results in a textile that meets the buyer’s hand and appearance specifications.