BH

A buttonhole, or BH in workshop shorthand, is a finished opening cut into fabric, usually in rows along the front of a garment, through which a button passes to fasten two layers of material together. The opening itself is rectangular or slightly curved, typically 6 to 12 mm wide depending on button diameter, with reinforced edges to prevent tearing and fraying under repeated use.

Buttonholes appear almost exclusively on shirts, coats, waistcoats, and similar tailored garments where buttons are the primary fastening method. Each BH must be positioned precisely: measurements are taken from a datum line (usually the center front of the garment) and marked before cutting. Industrial production uses specialized buttonhole machinery that cuts the opening, applies thread binding or piping around its perimeter, and sometimes produces a bar tack (reinforcing stitches) at each end, all in one operation.

The most common approach is thread binding: the cut edges are wrapped with tight overlock stitching, typically using polyester or nylon thread that matches the garment. More formal garments may receive piping, where a narrow bias strip is sewn into the cut edges for strength and appearance. Budget-conscious production sometimes relies solely on a dense zigzag stitch along the perimeter. The bar tack, a cluster of stitches perpendicular to the opening at each short end, prevents the buttonhole from splitting further if the button pulls hard against the fabric.

Quality control focuses on three critical points: precise length and width (measured to 0.5 mm tolerances in mass production), straight alignment perpendicular to the garment edge, and secure stitching that will not unravel after hundreds of wash cycles and button fastenings. Defects such as skipped stitches, frayed edges, or crooked cuts cause garment rejection. The strength of the finished BH depends equally on thread type, stitch density, and the stability of the base fabric; flimsy fabrics require additional reinforcement inside the garment to prevent the button from tearing through.

The term BH is understood across cutting rooms, sewing shops, and quality departments internationally, appearing on work tickets and spec sheets as a neutral abbreviation. It distinguishes the sewn component (the hole and its finishing) from the button itself, which is a separate part and fastening point. In some contexts, particularly in pattern-making, a buttonhole is also called a button slit or opening, but BH remains the standard shorthand in production environments.