Fibres, Yarns and Fabric Construction
What the domain tests
Fibres, Yarns and Fabric Construction examines how a raw fibre becomes cloth: fibre classification and properties, yarn structure and twist, and the main fabric-building routes. Questions often ask you to infer performance from structure rather than recall a trade name.
Fibres
Natural fibres are cellulosic (cotton, linen) or protein (wool, silk). Regenerated fibres such as viscose are made from dissolved cellulose; synthetics such as polyester, nylon and acrylic are polymer-based. Identify by origin, not by feel alone.
Yarns
Staple fibres are short and must be twisted; filament yarns are continuous. Twist direction is S or Z, and twist level affects strength, smoothness and absorbency. Yarn linear density is given in tex (g per 1000 m) or decitex. A plied yarn folds two or more singles.
Fabric construction
Woven fabrics interlace warp (lengthwise) and weft (crosswise). Plain weave has maximum interlacing; twill shows a diagonal; satin floats give lustre but snag. Weft knits stretch across the course; warp knits are more stable. Nonwovens are bonded webs, not yarn-based.
Worked example
A plain-weave cotton cloth is specified at 40 ends/cm, 30 picks/cm and 120 g/m². The warp has finer, higher-twist yarn than the weft. Reasoning: ends/cm is warp density; more ends and a finer warp give a smooth, strong face; lower picks allow weft coverage without stiffness. The 120 g/m² figure is area density, not yarn count, so it cannot tell you the tex.
Traps
Do not call polyester a fibre and twill a fibre; do not assume “natural” means strong when wet; do not confuse S and Z twist; do not use g/m² as a yarn count.