The singeing finishing process smoothes the surface of denim by removing the excess cotton fibres that give unfinished denim it’s “hairy” look.
This is done by running the fabric quickly over a flame one side at a time. Most denim—even most raw denim—goes through this finish. The video below shows how it’s done.
The “hairy” surface of unsinged denim is something denimheads love; it’s another characteristic of vintage denim. But while singeing affects the look and feel of a denim, it doesn’t do much to the way it fades.