SS

A side seam is the primary lengthwise seam running down the side of a garment, joining the front and back panels. In apparel manufacturing, it runs from armpit to hem on shirts, dresses, and similar items. The seam absorbs significant stress during wear and must be constructed to withstand repeated flexing, stretching, and laundering without separation or puckering.

The strength of an SS depends on thread choice, stitch density, and fabric preparation. Most side seams use a lockstitch or chainstitch, with thread count ranging from 16 to 20 stitches per inch depending on fabric weight. Polyester or cotton-wrapped polyester thread is standard; the wrap protects the core from moisture absorption and maintains elasticity on knit fabrics. On lightweight materials, the seam may be finished with a flat-fell or french seam construction to prevent raveling and reduce bulk.

Why it fails and how to avoid it

Puckering occurs when thread tension is uneven or when needle deflection happens on loosely woven fabrics. Seam slippage results from insufficient thread tension or undersized needles that fail to engage yarns deeply enough. On knit goods, skipped stitches indicate needle damage or incorrect needle type; ballpoint needles designed for knits prevent this. Operators must verify needle size, thread type, and bobbin tension before each run, especially when switching between fabric weights.

The term "side seam" distinguishes this seam from the shoulder seam (which joins front and back at the neckline), inseams (on sleeves or trouser legs), and construction seams used in pattern assembly. In industry shorthand, SS appears on work orders, quality checksheets, and specification documents. On finished garments, the SS is typically one of the last seams constructed, after shoulders and sleeves are joined, which means errors here are expensive to correct.