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.
Specimen Bed Porosity
Bed Calibration
The empty core holder of a gas pycnometer establishes the baseline volume before linen fibre is loaded into specimen bed porosity testing. Flax processing mills in Zhejiang apply this volumetric adjustment to raw line fibre samples drawn from baled harvests before commercial grading takes place. Gas expansion relies on Boyle law principles inside sealed chambers to calculate solid skeletal density against total geometrical volume.
Void Fraction
Air permeability coefficients determine how freely oxygen moves through compressed flax slivers during preparatory carding stages. Zhejiang spinning mills record void fractions on mill floor inspection sheets to verify that roving densities conform to buyer acceptance criteria before wet spinning begins. Fibre grade classification separates loose hackled flax from tightly packed tow based on these measured void ratios, whereas finished fabric grading evaluates completely different physical properties such as tensile strength and yarn evenness.
Permeability Ratio
Pressure drop measurements across packed flax cylinders quantify fluid resistance during subsequent alkaline boiling and bleaching treatments. Mill technicians track pressure differentials across the fibrous mass to ensure processing liquor circulates evenly without creating preferential channels in the material bed. Flow resistance values establish the baseline parameters that dictate chemical consumption rates throughout the entire wet finishing sequence.