Fabric Construction and Finishing
This domain examines how fabrics are made and finished. The exam tests your understanding of woven, knitted and nonwoven structures, basic weave names, fabric weight and the purpose of mechanical and chemical finishing.
Core rules
- Woven fabric is made by interlacing warp and weft yarns. Basic weaves are plain, twill and satin/sateen. Plain weave is firm and stable; twill shows a diagonal line; satin has long floats and high lustre.
- Knitted fabric is made by interlocking loops. Weft knitting uses courses and wales; warp knitting uses a different loop structure. Knits generally stretch more than woven fabrics.
- Nonwoven fabric is made from fibres bonded by heat, chemicals or mechanical action, not by yarn interlacing.
- GSM means grams per square metre. It is a measure of fabric mass per area, not thickness or quality by itself.
- Finishing includes singeing, desizing, scouring, bleaching, mercerising, calendering, sanforising, flame retardancy and easy-care treatments. Mechanical finishes change handle or surface; chemical finishes change properties.
Worked example
A 10 cm × 10 cm fabric sample weighs 2.4 g. Its area is 0.10 m × 0.10 m = 0.01 m². GSM = mass ÷ area = 2.4 g ÷ 0.01 m² = 240 g/m². Reasoning: convert the sample dimensions to metres before dividing; otherwise the result is wrong by a factor of 10,000. A running-metre weight cannot be found from GSM alone unless fabric width is known.
Traps that cost marks
Do not use centimetres directly as square metres. Do not equate high GSM with high quality; end use matters. Do not confuse sanforising, which controls shrinkage, with calendering, which gives surface smoothness. Do not describe knitting as interlacing warp and weft.
Key idea
Fabric structure and finishing must suit the product: durability for upholstery, drape for curtains, stretch for activewear.