Yarns and Fabrics
What the exam tests
Yarn structure, count systems, twist, and the three fabric-forming routes. Questions often ask you to identify a weave from a description or to compare fineness using count.
Core rules
- Staple yarns are made from short fibres; filament yarns from continuous filaments.
- S twist and Z twist describe direction; twist adds strength up to a point, then causes snarling and liveliness.
- Count: Ne (cotton count) = number of 840-yard hanks per pound, so higher Ne = finer; tex = grams per 1,000 m, so lower tex = finer; denier = grams per 9,000 m, lower denier = finer.
- Plain weave: 1 up, 1 down; firm, inexpensive, good for shirting and sheeting.
- Twill: diagonal lines; 2/2, 3/1 etc.; durable, good for denim and gabardine.
- Satin: long floats; lustrous, smooth, snag-prone; sateen is the cotton version.
- Knitted fabrics stretch; weft knits like jersey are common in T-shirts; warp knits like tricot are stable.
Worked example
A fabric is described as having a pronounced diagonal wale on the face, a 3/1 interlacing, and good abrasion resistance. Reasoning: the diagonal wale comes from twill interlacing; 3/1 means three warp ends up and one down, producing a warp-faced twill. Twill’s longer floats and compact structure explain the durability, so the answer is twill, not plain or satin.
Traps
- Saying a higher Ne count is coarser; it is finer.
- Confusing satin weave with sateen: sateen is a satin weave in cotton.
- Assuming knits are always weaker; structure and density matter.