Denim

Twill-weave fabric typically 100% cotton. The warp is indigo-dyed blue; the weft is undyed white. The blue-out, white-in is the defining characteristic.

Raw denim (rigid) is unwashed and shrinks 5-10% on first wash. Pre-washed is industrially washed and pre-shrunk. Raw fades more dramatically; pre-washed fades less.

Woven on shuttle looms (or modern equivalents with selvedge attachment). The self-finished edge is tight and does not unravel. Narrower width, more expensive, premium product.

With indigo, a vat dye. Indigo is reduced to its soluble leuco form, applied to the cotton warp, then oxidized by air to reform insoluble blue. Repeated dip-and-oxidize cycles (6-12 boxes) build the indigo color in multiple thin layers, giving denim its characteristic fade.

Conventional denim: 1,500-7,500 L per pair. Sustainable programs target < 500 L via closed-loop water recycling and organic cotton. Some laser-only programs use < 100 L per pair.