Determination of Bast Fiber Fineness via Standardized Low-Pressure Air Permeability
Low-pressure air permeability tests determine bast fiber fineness by measuring specific surface area across standardized compressed fiber plugs under ISO 2370.
Flax Bundle Linear Density
Mass Measurement
Raw flax fiber strands consist of technical fiber bundles bound together by pectin and lignin polymers, requiring standardized physical expression to quantify bundle thickness along a specified length. Measurements of flax bundle linear density express this mass relationship in tex or decitex units to establish the physical fineness of long-line flax before hackling and drafting. Modern Chinese linen mills test raw fiber shipments against laboratory samples to confirm whether the fiber bundles meet drafting tolerances for targeted yarn counts.
The measurement defines the structural thickness of unrefined fibers and ceases to apply once chemical degumming or mechanical splitting breaks pectin bonds into individual elementary fibers.
Hackling Yield
Comb pin spacing on industrial hackling frames directly dictates how effectively technical fiber bundles split during mechanical carding. Processing raw fiber with elevated flax bundle linear density requires tighter pin density adjustments and slower feed roller velocities to prevent fiber breakage. Fiber lots exhibiting coarse bundle structures produce higher percentages of tow fiber during hackling, altering the yield ratio between long line flax and short fibers.
Mill technicians record these bundle dimensions across raw fiber lots to adjust pin schedules on drafting machinery.
Spinning Limit
Maximum achievable yarn fineness depends on the average number of individual bundle strands present in a cross-section of roving. High flax bundle linear density restricts the maximum spinning count because coarse bundles cannot form uniform yarn cross-sections in fine metric counts. When spinning mills produce fine wet-spun yarns, raw material specifications demand low linear density values to prevent thick places and slubs.
Yarns spun from improperly matched bundle sizes exhibit uneven tensile strength along the bobbin length.
Basic Methods for Measuring Flax Fiber Length Distribution
Accurate measurement of flax fiber length distribution requires converting between numerical count and mass-weighted metrics to control drafting waves.