Definition
A cut-on facing is a facing cut in one piece with the garment, as an extension of its edge, then folded back to the inside instead of being sewn on.
When an edge is straight, a separate facing and seam are unnecessary: the pattern piece extends past the edge by the width of the facing, and that extension folds back along a fold line. You save a seam, reduce bulk and get a crisp folded edge.
Where you find them:
- Button fronts of blouses and dresses, where the facing carries the buttons and buttonholes and is interfaced.
- Center back openings on skirts and dresses with a zip or buttons.
- Front edges of jackets and cardigans.
- Hems and pocket tops, which work the same way.
A cut-on facing often joins a separate neck facing at the shoulder or neckline, since the curve at the top cannot be folded back.
Its limits: it only works where the edge is straight or nearly so, it uses more fabric because the facing is part of each piece, and it shares the grain of the garment piece, with no option to cut it differently.
Interface the facing half, or the garment half for a crisper outside, and press the fold before construction. Mark the fold line with small snips at the top and bottom.
The button-front version of the woven top is a good example. Compare with a separate facing and with a placket.