Jute Fibre Quality Testing
topic
Jute fibre quality testing evaluates fineness, strength, length, colour, and root content of raw jute bales for spinning, packaging, and geotextile applications. Fibre fineness (gravimetric, Nm 1.0–3.0 for spinning grade, 0.5–1.5 for industrial grade) is measured by the Suter Webb airflow fineness tester (calibrated for jute, 20 g sample, result Nm) or bundle gravimetric method (Nm = 1000/Tex). Tensile bundle strength (Pressley bundle tester, 3.2 mm jaw spacing, 100 fibre bundle, strength index in lbs/mg — Bangladesh standard: Grade 1 Pressley index >6.0, Grade 2 >5.0). Colour grading (Bangladesh Jute Grading Manual 7 grades — Especial to Cuttings, visual assessment by approved classers under D65 illuminant) determines commercial grade — Especial grade commands 30–50% price premium over Common grade. Root content (% by weight of fibre below 25 mm from root end, optimum <5% for spinning quality) — excessive root content causes breakage during carding. Moisture content (oven-dry, ISO 6741-1, standard moisture regain 13.75% for jute at 65% RH, 20°C) affects bale weight and trade value — above 17% moisture promotes microbial degradation during storage. Jute Strength Tester (JST, Bangladesh) measures 50-fibre bundle breaking strength with automated clamp and data recording. Alkali solubility test (1% NaOH 30 min 100°C, % dissolution) indicates cellulose degradation from microbial retting — >18% dissolution signals over-retted fibre with reduced strength.
Role
Jute fibre testing provides the grade classification data underpinning the $1.8 billion global raw jute trade concentrated in Bangladesh and India, where fibre grade determined by fineness, strength, and colour directly governs the price received by 4 million jute-farming households and the raw material cost for jute mills processing 3.5 million tonnes annually.