The structure of yarns and the main methods of fabric construction (weaving, knitting and non-woven), and how each affects the appearance, properties and performance of the resulting fabric

What this dot point is asking

You need to explain how yarns are made and how the three main construction methods, weaving, knitting and non-woven, turn fibres and yarns into fabric with particular properties. The key idea is that construction changes performance independently of the fibre: the same fibre woven, knitted or bonded behaves very differently. Markers reward answers that link the structure of a fabric to how it performs and to a suitable end use.

Yarn structure

A yarn is the intermediate stage between fibre and fabric. Spun yarns are made by twisting short staple fibres together; more twist gives a stronger, smoother, firmer yarn, while less twist gives a softer, bulkier yarn. Filament yarns use long continuous strands and can be smooth (giving lustre and strength) or textured (crimped to add bulk, stretch and warmth). Ply refers to the number of single yarns twisted together, which adds strength and evenness. Yarn choice affects the final fabric: a tightly twisted yarn produces a crisp, durable fabric, while a soft, low twist yarn produces a fabric that is warm and soft but pills more easily.

Weaving

Weaving interlaces two sets of yarns at right angles: warp yarns running lengthwise and weft yarns running crosswise. The pattern of interlacing is the weave. Plain weave (each weft over and under each warp) is firm, hard wearing and stable, used for shirting and calico. Twill weave creates diagonal lines and is strong and drapeable, used for denim. Satin weave floats yarns over the surface to give lustre and smoothness but snags easily. Woven fabrics are generally stable, hold their shape, fray at cut edges, and stretch most on the bias. They suit structured garments, furnishings and items needing dimensional stability.

Knitting

Knitting interlocks loops of yarn. Weft knitting builds rows of loops across the fabric (as in hand knitting and jersey), giving stretch in all directions, softness and comfort, but it can ladder and lose shape. Warp knitting forms loops along the length (as in tricot), producing a more stable knit that resists laddering. Knitted fabrics are elastic, breathable and comfortable, making them ideal for t-shirts, underwear, socks and activewear, but they are less dimensionally stable than wovens and can curl at the edges.

Non-woven construction

Non-woven fabrics are made directly from fibres bonded together without spinning yarn or weaving, using heat, adhesive, moisture or mechanical entanglement (as in felting and needle punching). They are quick and cheap to produce, do not fray, and can be engineered for specific uses. They are usually weaker and less drapeable than wovens or knits. Common uses include interfacing, wipes, surgical masks, geotextiles and disposable products. Felt, a traditional non-woven made from wool, is the historical example of fibres bonded by heat, moisture and pressure.

Linking construction to performance

The exam skill is choosing or justifying a construction for an end use. A pair of jeans needs strength and stability, so a twill weave of cotton suits it. A t-shirt needs stretch and comfort, so a weft knit suits it. Disposable cleaning cloths need to be cheap and absorbent without fraying, so a non-woven suits them. The construction works alongside the fibre and any finishes to deliver the required performance, and a complete answer names all three influences where relevant.