Overview
ISO 2370:2019 - Textiles - Determination of fineness of flax fibres - Permeametric methods defines laboratory procedures to measure the fineness of flax (linseed) fibres using permeametric (air‑flow) techniques. The standard specifies three validated methods - two constant‑flow variants and one constant‑pressure method - applicable to flax in all forms (long strands, broken strands, tow, slivers) and at all stages of manufacture.
Key topics and technical requirements
- Three permeametric methods
- Constant flow method (Clause 5): uses a test piece of parallel fibres and two compressions to obtain two resistance measurements and calculate specific surface and density.
- Simplified constant flow method (Clause 6): uses fibres distributed “at random”, one compression, and a single resistance measurement.
- Constant pressure method (Clause 7): constant pressure measurement with one compression for randomly distributed test pieces.
- Test pieces and sampling
- Test pieces typically are wads about 80 mm ± 1 mm long; for the parallel‑fibre method masses are specified (e.g., 2.8 g to 3.2 g depending on material). Sampling is to be representative and may use methods in ISO 1130.
- Measured quantities
- Resistance of a wad to airflow (R), specific surface (A), index of specific surface (A′) and the index of fineness standard (IFS) derived from permeametric data.
- Apparatus & controls
- Apparatus components specified include an air tap/compressor, pressure gauge, output control (butterfly valve), output meter (e.g., soap‑bubble meter), measuring chamber and manometer. Minimum compressed air pressure and gauge ranges are given in the standard.
- Environmental conditions
- Conditioning and testing in the standard textile atmosphere defined by ISO 139.
- Quality control
- Procedures for controlling apparatus functioning, calculating results and preparing a test report are included.
Applications and who uses it
ISO 2370:2019 is used by:
- Textile testing laboratories performing flax fibre characterization
- Flax processors and scutching/card clothing operations monitoring fibre quality
- Spinning mills and composite material manufacturers requiring fineness data for processing or product specification
- Quality assurance and standards teams establishing acceptance criteria or reference data
Practical benefits include repeatable, comparable fineness measurements that inform processing decisions (e.g., carding, drafting, spinning) and material selection.
Related standards
- ISO 139 - Standard atmospheres for conditioning and testing textiles (conditioning requirements referenced)
- ISO 1130 - Textile fibres - Sampling methods for testing (sampling guidance)
Keywords: ISO 2370, fineness of flax fibres, permeametric methods, constant flow method, constant pressure method, textile testing, flax fibre fineness determination.