The selvedge outseam

What it is

The outseam is the seam running down the outside of a trouser leg. On a jean cut from selvedge denim, the pattern is laid so that the finished edge of the cloth becomes the seam allowance on that seam. The two pieces are sewn together, the seam is pressed open, and the selvedge edges are left exactly as they came off the loom. No felling, no overlocking, no binding — the edge is already finished.

Turn up the cuff and you see it: two parallel lines of selvedge, sitting flat, with the mill's coloured thread running along them.

Why it was chosen

Because it is the simplest correct seam for that cloth. The edge does not fray, so it does not need enclosing; a pressed-open seam is the flattest seam there is; and it says plainly what the garment is cut from. It also keeps the outseam narrow. On the Standard Issue Jean the allowance is 1 cm — set by the width of the selvedge itself, not by a construction choice.

The pattern pays for this. Every leg piece has to be laid out with its outseam edge on the selvedge, which fixes where the pieces sit on a cloth that is less than a metre wide, and decides how much cloth a pair takes.

Where it appears

The Standard Issue Jean, on both legs. The inseam of the same jean is the opposite approach — a flat-felled seam with a wider allowance, enclosed and stitched down.

What it changes

Functionally, a pressed-open outseam is flatter and less stiff than a felled one, and it makes the leg width a little easier to adjust later, since there is a plain seam to let out or take in. Visually, it is quiet until the cuff is turned. Over time the selvedge stays crisp while the cloth around it fades, so the contrast at a cuff grows rather than wears away.