Thread

What it is

Thread is the yarn a garment is sewn with. It is easy to ignore because it is small, and it is the thing that fails when a seam fails. The Bench Note Thread matters is the opinion; this is the reference.

Three things describe a thread: what it is made of, how heavy it is, and what it is for.

• Fibre. Cotton is traditional, takes dye like the cloth, and fades with it. Polyester is stronger for its size and does not rot. A core-spun thread wraps cotton around a polyester core and behaves like cotton on the surface with polyester's strength inside. Most construction here is core-spun.
• Weight. Thread comes in sizes; a heavier thread makes a bolder, more visible stitch and needs a bigger needle. The visible stitches on a jean are heavier than the ones holding the pocket bag together.
• Job. Construction thread holds the garment together and mostly disappears into the seam. Topstitching thread sits on the surface and is chosen for how it looks as much as how it holds — see Topstitching.

Why it matters here

A seam is only as strong as its thread, and a repair is only as easy as its thread lets it be. Cheap thread breaks under a rivet, frays where it rubs, and cannot be matched later. Good thread costs more per spool and almost nothing per garment.

There is one place cheap thread is right: the toile, or muslin — the fitting sample that exists to be measured, marked, unpicked and thrown away. Those are sewn with plain, inexpensive polyester, so the good thread goes into garments that will last.

How it wears

Cotton and core-spun topstitching fades and softens along with the cloth, which is why an old jean's stitching looks like it belongs. Polyester stays the colour it started. Where thread rubs — the hem, the fly, the pocket mouths — it goes first, and that is the seam to watch for a small early repair.