Seams and sewing techniques: a catalogue of the trade's techniques
From the simple straight seam to finish that must withstand wash after wash
The seam is the place where two pieces of fabric become one garment, and the choice of seam type is far from random. The right seam depends on the fabric's properties, where on the garment it sits, and how much strain it needs to withstand. An experienced clothing craftsperson chooses a seam the way a carpenter chooses a joint — based on function, not habit.
§The flat seam — the foundation
The ordinary straight seam is the trade's most used seam: two fabric layers are placed right-to-right and sewn together with a straight stitch line. It is fast, strong enough for most firm fabrics, and forms the basis for most other seam types, which simply add extra processing of the seam allowance or edges.
§French seam — the hidden, neat edge
With a French seam, the fabric is first sewn wrong side to wrong side, the seam allowance is cut down and the parts are turned and sewn again right side to right side so the raw edge is completely enclosed in the seam. The result is a seam without visible raw edges on either side of the fabric — suitable for thin and transparent fabrics where a regular plain-sewn edge would spoil the appearance.
§Overlock stitch — the seam that edges in the same grip
The overlock machine (lock machine) sews and edges the fabric simultaneously with chain stitch that surrounds the edge so it does not fray. It is fast, strong and especially suitable for stretch fabrics like jersey, because the stitches themselves can stretch with the fabric without breaking — something an ordinary straight seam struggles with.
§Flat seam and flat seam
A flat felled seam lays two layers of fabric on top of each other with an overlap, which is sewn down with two parallel rows of stitches — as you often see on jeans and workwear. It is very strong and flat to wear because there is no seam allowance sticking out, and is therefore used for areas with high stress or close body contact.
| Seam type | Characteristic | Typical use |
|---|---|---|
| Flat seam | Simple, fast straight to straight | Most solid substances |
| French seam | Double-stitched, hides raw edge | Thin, transparent fabrics |
| Overlock stitch | Sew and trim edges at the same time | Stretchable fabrics such as jersey |
| Flat seam/flat seam | Flat very strong | Jeans, work clothes, high stress |
| Blind stitch | Invisible from the legal side | Trimming edges and clipping |
§Blind stitch and finish
For hemming lower edges, where the seam should preferably not be visible from the right side, a blind stitch is used — either sewn by hand or on a special machine that only takes a small stitch on the very edge of the fabric. Combined with proper edge finish, pressing and removal of loose threads, these are the final touches that determine whether a garment looks homemade or professional.
“The seam may not always be visible — but it's felt every time the garment is worn.”