Textile Fibres and Yarn Fundamentals
This domain tests whether you can classify a fibre, quote its key physical values, and convert between yarn count systems - the arithmetic that underpins every later costing and fabric calculation.
Fibre classification
- Natural: cellulosic (cotton, linen, jute), protein (wool, silk), mineral (asbestos).
- Manmade: regenerated (viscose, modal, lyocell), synthetic (polyester, nylon 6 and 6.6, acrylic, elastane), inorganic (glass).
- Staple fibres are measured in mm and spun; filaments are continuous and measured in denier.
Values worth memorising
- Cotton: staple 10-65 mm, moisture regain 8.5%, tenacity 3-4.5 g/den, damaged by acid, resistant to alkali (hence scouring in alkali).
- Wool: scales plus crimp cause felting; regain 13-16%; sensitive to chlorine.
- Polyester: regain 0.4%, hydrophobic and oleophilic, so it releases oil stains poorly but dries fast.
Count systems
- Ne (cotton count) = number of 840-yard hanks in 1 lb. Higher Ne = finer yarn.
- tex = grams per 1000 m; denier = grams per 9000 m.
- Conversion chain: tex = 590.5 / Ne, and denier = 9 x tex.
Worked example
A supplier quotes 40s Ne combed cotton. What is it in tex and denier? tex = 590.5 / 40 = 14.76 tex. denier = 9 x 14.76 = 132.9, i.e. about 133 denier. Reasoning: convert Ne to tex first because tex is a direct-mass unit; converting Ne straight to denier invites a factor-of-9 error.
Traps that cost marks
- Assuming a higher count number means a coarser yarn; for Ne it is the reverse.
- Mixing tex and denier in the same formula.
- Quoting count without stating the conditioning atmosphere (standard: 20 C, 65% RH); an unconditioned sample gives a false count.
- Writing the spinning sequence out of order. For cotton it is: blow room, carding, drawing, roving (simplex), ring spinning.