Textile Fibres and Yarn Science
Textile Fibres and Yarn Science
This domain tests fibre classification, properties, and the numerical language of yarns: count, twist and blending. Questions often ask you to place a fibre in the correct group and convert a count correctly.
Fibre classification
- Natural cellulose: cotton, linen, jute. Natural protein: wool, silk.
- Regenerated man-made: viscose, modal, acetate. Synthetic: polyester, nylon, acrylic, elastane.
- Staple fibres are short and must be twisted into yarn; filament fibres are continuous. Silk is a natural filament; cotton is a staple.
Yarn count and twist
Indirect count (Ne) falls as yarn becomes coarser: Ne is the number of 840-yard hanks per pound. Direct count (tex) rises as yarn becomes coarser: tex = grams per 1,000 m; denier = grams per 9,000 m. Conversion: tex = 590.5 ÷ Ne. Twist direction is S or Z; twist factor affects handle and strength.
Worked example
A cotton yarn is labelled 20s Ne. Convert it to tex and explain the result. Tex = 590.5 ÷ 20 = 29.5 tex, so 1,000 m weighs about 29.5 g. A 40s Ne yarn would be 590.5 ÷ 40 = 14.8 tex. Reasoning: Ne is indirect, so a larger Ne number means a finer yarn and a smaller tex value.
Traps
Do not say higher denier is finer-higher denier is coarser. Do not use 590.5 to convert to denier. Do not call viscose synthetic; it is regenerated. Do not assume every natural fibre is staple.
Key points
- Cotton and linen are cellulose; wool and silk are protein.
- Staple versus filament changes spinning method and yarn appearance.
- Ne is indirect; tex and denier are direct.
- Higher Ne = finer yarn; higher tex or denier = coarser yarn.
- S-twist and Z-twist describe spiral direction, not count.