Fading and black denim

Why indigo fades the way it does

Indigo does not soak into cotton. It sits on the surface of the yarn in layers, and the core of the yarn stays white — which you can see if you cut a thread. Most denim is dyed by dipping a rope of yarn repeatedly, so the layers build up on the outside.

Wear scrapes those layers off. Wherever the cloth creases, folds or rubs — behind the knee, across the lap, along the seams, at the pocket mouths, under the belt — the surface wears down to the pale core. Everywhere else it fades slowly and evenly with each wash. The result is a map of how the garment was worn, and it is unique to the wearer.

Rope-dyed, ring-spun denim fades with the sharpest contrast, which is why it is prized. The material page for a denim says how it was dyed and spun.

Why black is different

Black denim is not indigo. It is usually dyed with a sulphur dye that penetrates the yarn more fully and does not have a white core to show. Two things follow:

• It does not fade to white. It fades to grey — first at the same rub points, then overall — and the effect is softer and more even.
• It shows wear on the surface as a slight sheen and a slight dustiness rather than as high-contrast lines.

A black denim will also lose colour in the wash more evenly across the garment than an indigo does. A worn black jean is a charcoal jean, and that is the intended life of the cloth, not a failure of it.

What this means for the work here

Both are used, and the difference is part of the choice. The Foundry Jacket's indigo will map its wear. A jean cut from a black selvedge will go grey along the seams and topstitching first, and the contrast will be quiet.

Topstitching goes first on either, because the thread sits proud of the cloth — see Topstitching. Washing habits are under Washing denim; none of them stops fading, and none should.