Denim
Fabric — one of 56 in the glossary
A rugged cotton twill woven from an indigo-dyed warp and an undyed filling, which is why the face is blue and the reverse is pale. The indigo sits on the outside of the yarn rather than penetrating it, so denim fades where it rubs — the basis of every wash and distressing treatment sold. Weight is quoted in ounces per square yard, with 8-10 oz for shirts and 12-14 oz for jeans. It embroiders well and takes a screen print, but expect the indigo in unwashed denim to crock onto light-coloured ink and plan for a heavier deposit.
Blue on the outside only
Denim is a cotton twill woven from an indigo-dyed warp and an undyed weft. The twill structure puts mostly warp on the face and mostly weft on the reverse, which is why the outside is blue and the inside is pale.
Indigo is a surface dye: it clings to the outside of the yarn rather than penetrating to the core. Abrade the yarn and the white core shows through.
That is the entire mechanism behind denim fading at knees, seams and pocket edges — the colour is being worn off, not washed out.
Reading the weight
Denim is quoted in ounces per square yard, and the range is wide: around 10 oz is light, 12 to 14 oz is standard, and above 16 oz is heavyweight.
Heavier denim is stiffer, lasts longer and takes much longer to break in. Lighter denim is comfortable immediately and wears out sooner.
Raw or dry denim has not been washed after dyeing, so it is stiff and fades according to how the wearer moves. Washed denim has been processed to soften and fade it at the mill.
Decorating it
It is a heavy woven twill, so it is stable and hoops well, and embroidery is the common decoration on caps and jackets.
The diagonal texture shows through a thin ink film, and the indigo can crock — rub off onto other surfaces — which matters against a light print.
Heavy denim needs a firm hoop and the right needle; standard apparel embroidery settings will fight it.
Common questions
- Why does denim fade?
- Because indigo sits on the outside of the yarn rather than soaking into it. Abrasion wears the dyed surface away and exposes the white core, which is why fading follows wear points.
- Why is the inside of jeans white?
- Denim is a twill woven from an indigo warp and an undyed weft. The structure puts warp on the face and weft on the reverse, so the outside is blue and the inside is pale.
- What is raw denim?
- Denim that has not been washed after dyeing. It is stiff at first and fades according to how the wearer moves, rather than being pre-faded at the mill.
- What weight should denim be?
- Around 10 oz is lightweight, 12 to 14 oz standard, and 16 oz and above heavyweight. Heavier lasts longer and takes much longer to break in.
See also
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