Identifying Primary Causes of Warp Streaks in Woven Fabrics
Warp streaks stem from localized end-spacing variations, tension differentials during beaming, linear density fluctuations, or unequal sizing penetration.
Sizing Solids Penetration
Treatment Performance
Deposition of sizing agents into the core of flax yarn rather than just on its outer surface enhances the yarn’s tensile strength and smoothness. This distribution of starch or synthetic polymers is termed sizing solids penetration during the yarn preparation phase. It ensures that the fibers within the yarn bundle are bound together, reducing yarn hairiness and friction during weaving.
Proper sizing is necessary for linen yarns due to their coarse and rigid nature.
Absorption Mechanism
Size solution density and squeeze roller pressure on the sizing machine regulate how deeply the liquid polymer penetrates into the yarn structure. During the sizing stage, the flax yarn passes through a size box filled with hot starch or synthetic agents before passing through squeezing rollers. High roller pressure forces the sizing mixture into the yarn core, ensuring adequate sizing solids penetration, while the temperature is maintained at ninety degrees Celsius.
This process is monitored by measuring the wet pick-up rate and the moisture content, with all data logged in the sizing department report. If the size remains only on the surface, it will flake off on the loom, leading to high yarn breakage rates.
Weavability Improvement
Laboratory testing of the sized yarn evaluates the starch distribution by staining yarn cross-sections with iodine and viewing them under a microscope. The test results are recorded in the sized yarn analysis sheet, which must show a penetration rate of at least thirty percent of the yarn radius. This internal mill standard is necessary to achieve high weaving efficiency on modern air-jet looms.
Meeting these criteria ensures that the woven linen fabric contains fewer weaving defects and satisfies the buyer’s acceptance criteria for yarn smoothness and weave quality.