Bast Fibre Testing

Bast fibre testing characterises the fineness, tensile strength, length, surface properties, and retting quality of flax, hemp, jute, ramie, and kenaf fibres that determine their suitability for fine linen spinning, technical composite reinforcement, or coarse industrial textile applications. Bast fibre fineness is expressed as airflow fineness (Nm or dtex equivalent), gravimetric count, or fibre diameter (µm) measured by microscopy or OFDA — flax line fibre fineness 2–10 Nm (100–500 dtex), ramie 3–7 Nm (143–333 dtex), jute 1–3 Nm (333–1,000 dtex). Single fibre tensile properties (Textechno Favimat+, ISO 11566 carbon fibre adapted to bast fibre, 20 mm gauge length, 2 mm/min extension): flax single fibre tenacity 500–1,500 MPa, modulus 40–80 GPa; hemp 400–800 MPa, 30–60 GPa; jute 300–500 MPa, 10–30 GPa — substantial property variation due to natural variability, retting degree, and test specimen preparation difficulty (fibre isolation without damage). Retting degree assessment (Belgian retting scale 1–5 or Schmutz method) critically affects fibre fineness and bundle separation — under-retted fibre bundles (10–20 individual fibres, diameter 50–100 µm) versus well-retted technical fibres (5–10 fibres, diameter 20–50 µm) differ 3–5× in fineness and 2–3× in composite interfacial bonding strength.