Determining Flax Fibre Fineness and Area Distribution Parameters
Flax fibre fineness and area distribution parameters govern wet-spinning limits, bundle drafting cohesion, hackling yield, and yarn tenacity.
WIRA Airflow Fineness
Permeability Measurement
Airflow resistance testing measures the specific surface area of porous fibre plugs by recording air pressure differential across a standardized chamber. In wool and bast fibre testing laboratories, WIRA airflow fineness assesses fibre bundle thinness by measuring air permeability through a weighed sample of compressed flax. Coarse fibre bundles present low surface area, permitting rapid airflow and registering high scale values.
Fine, well-retted bundles restrict air passage, generating higher pressure drops that correspond to lower micron readings.
Laboratory Calibration
Mill testing facilities utilize rapid airflow instruments to screen incoming raw flax lots before spinning preparation. Measuring WIRA airflow fineness provides a fast alternative to time-consuming microscopic cell counting or manual gravimetric cutting. Technicians calibrate the apparatus using reference fibre standards under controlled temperature and relative humidity.
Data from airflow testing guides mill blending operators in combining different raw lots to achieve target yarn counts. Maintaining consistent permeability values across raw blends reduces yarn unevenness and minimizes end breaks during wet spinning frame operation.
Operating Boundary
Airflow permeability testing requires clean, parallel fibre samples free of extraneous shive matter or chemical sizing. Measurement accuracy fails when testing crimped roving or twisted finished yarn, where mechanical compaction distorts natural air passages.