Measurement Standard
International testing protocols define the procedure for measuring the average diameter of flax fibres using air permeability. The methodology described in iso 2370 air flow fineness relies on forcing a constant volume of air through a compressed mass of fibres. This test provides a rapid and objective assessment of fibre fineness for quality grading.
Technical Execution
Specimen preparation requires cleaning the scutched flax to remove dust and non-cellulosic shives before testing. A technician weighs a five-gram specimen of parallel flax fibres and packs it into the cylindrical test chamber of the airflow apparatus. When air is drawn through the chamber, the resistance to the flow is measured by a rotameter or a pressure gauge.
Under the rules of iso 2370 air flow fineness, higher resistance indicates finer fibres because of their greater total surface area. The resulting flow value is converted to a fineness index on the laboratory test sheet.
Industrial Application
Spinning performance is predicted directly from the measured airflow resistance of the raw flax shipment. Fine fibres are reserved for high-count warp yarns, while coarser batches are diverted to heavy weft yarns or technical fabrics. The buyer’s purchase agreement specifies the acceptable range of airflow values for each yarn grade.
This classification prevents yarn breakage during high-speed spinning operations.
