Fibres and Yarns: Types, Properties and Identification
What the domain covers
This domain tests fibre classification, essential properties, yarn structure, and practical identification. You should distinguish natural and manufactured fibres, staple and filament yarns, and simple spun versus textured yarns.
Core rules and concepts
- Natural fibres: cotton, flax, wool, silk. Manufactured: viscose, polyester, nylon, acrylic, elastane.
- Staple fibres are short and spun; filament fibres are long and may be textured or flat.
- Yarn properties depend on fibre type, staple length, twist direction, twist level, and count. Higher twist generally gives a stronger, leaner yarn but can reduce softness.
- Blends combine properties; a poly-cotton blend improves strength and wrinkle recovery but changes burning behaviour.
- Identification uses burning, microscopy, solubility, and physical tests. No single test is conclusive for blends.
Worked example
A white fibre burns quickly, smells like burning paper, and leaves soft grey ash. Reasoning: paper smell and grey ash point to a cellulose fibre, most likely cotton. A polyester sample would melt, shrink away from the flame, and form a hard black bead with a chemical odour. Because the first sample could be viscose, confirmation would need a solubility or microscopy check.
Traps that cost marks
- Calling a yarn a fibre, or a fabric a yarn.
- Relying on flame tests alone, especially for blends and flame-retardant finishes.
- Mixing up filament and staple properties.
- Forgetting that twist and count affect handle, strength, and appearance.
Exam focus
Use a decision sequence: feel and appearance → burn behaviour → confirmatory test → fibre or blend conclusion.