Overlock Stitch (Serging)

An overlock stitch, the technical name for what most people call serging, runs on a fast machine with multiple thread cones that trims the raw fabric edge and wraps it in interlocking loops in one motion. Most garment overlockers run 3 or 4 threads and stitch at speeds up to 8,000 to 9,000 stitches per minute, which is why serging is the fastest way to finish a raw edge in bulk production.

Flip any decent tee inside out and the shoulder seams, side seams, or sleeve-set seams show this looped overlock stitch binding the raw edge; it's what keeps a cut knit edge from unraveling into a fringe of loose yarn after a few washes. Cheap blanks sometimes skip a real overlock and just fold-stitch the edge instead, and those seams shed thread and curl noticeably faster.

When evaluating a new blank supplier, turn a sample inside out and check the overlock stitch quality at the underarm and side seam, looking for even stitch length, no skipped loops, no puckering, before committing to a bulk order, since that seam takes the most stress in wear.

Buyers sometimes assume overlock stitching alone makes a seam stretchy, but a standard overlock stitch just binds the edge; it's the seam construction underneath, like a flatlock or coverstitch, that actually determines how much a seam flexes with the body.