Hemp Cottonisation for Cotton-System Spinning

Cottonisation reduces hemp technical fibre bundle linear density from 5–50 tex to 1.5–5 dtex approaching cotton fineness (1.2–2.5 dtex) through chemical, enzymatic, or combined treatments enabling processing on standard cotton ring-spinning frames. Chemical cottonisation uses NaOH (10–20%, 120–150°C, 30–90 min) degrading hemicellulose and pectin, reducing bundle size by 70–85% but causing 15–25% cellulose DP reduction and 10–20% strength loss. Enzymatic cottonisation (cellulase 0.5–2.0% owf + pectinase 0.2–0.5% owf, 50°C, pH 5.0, 2–6 hours) achieves 60–75% bundle size reduction with only 5–10% strength loss, producing cottonised fibre with fineness 2–5 dtex, length 20–38 mm and spinnable on cotton cards and ring frames at Ne 10–30. Hemp-cotton blends of 30–50% cottonised hemp + 50–70% cotton are most common for apparel knitwear. Cottonised hemp at 100% is spinnable at Ne 10–20 on rotor spinning. Processing adds €0.50–1.20/kg fibre cost but unlocks access to global cotton spinning infrastructure representing 70 million spindles worldwide.