Definition
A raw edge is the unfinished cut edge of a piece of fabric, which can fray on wovens or curl on knits until it is finished, enclosed or hemmed.
Instructions mention raw edges constantly: "with raw edges aligned", "fold the raw edge under 1 cm", "finish the raw edges". The term separates a cut edge from a finished one, such as a hem, a fold, a selvedge or a bound edge.
What happens to raw edges:
- Woven fabrics fray. Threads slip out along the edge, slowly on firm cotton, quickly on linen, viscose and loose weaves. A seam finish or an enclosed seam stops it.
- Knit fabrics do not fray, but they may curl, like jersey, or ladder from one end. They are often left raw inside, or finished for neatness.
- Felt, fleece, leather and boiled wool have no threads to unravel and can be left raw on purpose.
Raw edges can also be a design choice: frayed denim hems, cut-edge jersey hems, raw-edge appliqué and fringed linen napkins.
When pieces are sewn "raw edges together", line them up exactly, because the seam allowance is measured from that edge. Handle raw edges cut on curves or on the bias gently, since they stretch.
With fabrics that fray heavily, many sewists zigzag or overlock the edges of each piece right after cutting, before any construction, so the seam allowances survive handling and fitting.