The looms at Kuroda Mill are older than the people who run them. They weave a narrow cloth, about 80 centimetres wide, slowly, with a shuttle that passes the weft through the warp and leaves a clean finished edge on both sides. That edge is the selvedge: self-finished, so it never frays.
Why the narrow cloth matters
A wide modern loom is faster and cheaper. A shuttle loom is gentler on the yarn, which is slightly irregular and slightly slubby, and that irregularity is what gives the cloth its depth once it fades. We cut with the selvedge on the outseam, so a rolled cuff shows the mill's ID line.
Rope dyed
The yarn is dipped in indigo and lifted into the air to oxidise, from green to blue, dip after dip. Because the core stays white, the denim fades from the outside in. That is why a pair gets better with wear.