Fabric Knowledge
This domain tests fibre families, weave names, grain behaviour and the small calculations that stop a finished garment shrinking or twisting out of shape.
Fibres and their behaviour
- Natural: cotton is absorbent but creases and shrinks 3–5%; linen is strong and stiff but creases badly; silk is lustrous and needs gentle hand wash or dry clean; wool is warm and felts in hot water with agitation.
- Regenerated: viscose rayon drapes softly but is weak when wet. Synthetics: polyester is strong and quick-drying, nylon very strong with low absorbency, acrylic wool-like.
- Blends: poly-cotton 67/33 for uniforms and shirting; cotton-lycra for churidar and leggings.
Construction
- Plain weave: poplin, cambric, voile, muslin - stable, little stretch.
- Twill, diagonal lines: denim, drill, gabardine - stronger and hides stains.
- Satin: long floats give shine but snag easily. Pile: corduroy and velvet, which have a nap.
- Knits: single jersey curls at the edges, rib stretches most crosswise, interlock is stable on both faces.
Grain, selvedge and bias
- Warp threads run lengthwise, parallel to the selvedge; strongest, least stretch, and the direction the grainline arrow follows.
- Weft runs crosswise with more give. The 45° bias has maximum stretch and is used for bias binding and cowl drape.
- Off-grain fabric hangs twisted after washing. Straighten by drawing a crosswise thread and cutting along the line.
Worked example
Finished kurta length is 2.00 m and the cotton shrinks 5%. Required pre-shrunk length = 2.00 ÷ 0.95 = 2.11 m. Add 10 cm for seam allowances and matching: buy 2.21 m, so purchase 2.25 m, not 2.00 m.
Traps
- Testing shrinkage after the garment is cut.
- Treating the crosswise weft as the grainline.
- Cutting directional prints and napped fabrics with pieces facing different ways.