Sewing Princess Seams Smoothly Over a Curve

The center panel of a princess-seamed bodice has a convex, outward-curving edge over the bust, while the side panel has a concave, inward-curving edge. When laid flat they look mismatched, and they are: the seam is designed to pull a flat piece of fabric into a rounded shape over the body, so the edges only make sense once joined and worn.

This mismatch is the whole point. The seam builds shaping directly into the join rather than into a separate dart, which is what gives princess lines their smooth, uninterrupted appearance. It also means the two edges must be handled differently as you sew.

Before joining, staystitch the concave edge just inside the seam line to stop it stretching as you handle and clip it. The bias portion of these curves distorts easily, and a stretched edge will never match its partner. Transfer all the notches accurately, because they are the only reliable way to distribute the curve evenly.

Pin with the concave, staystitched piece on top, matching notches first and easing the fabric between them. The convex edge has slightly more length to fit around the fullest point, so ease it in gently rather than stretching the concave edge to reach. Working notch to notch keeps the fullness where the bust needs it.

1. 1.Stitch the seam slowly, keeping the curved edges aligned and easing between notches.
2. 2.On the concave side allowance, clip inward snips up to the staystitching so the allowance can spread.
3. 3.On the convex side allowance, cut small wedge notches so the allowance can compress.
4. 4.Space the clips and notches closest together at the tightest part of the curve, over the bust point.
5. 5.Check the seam lies flat before pressing, adding more clips only where it still pulls.

A princess seam is a three-dimensional shape and cannot be pressed flat on a board without crushing the very roundness it creates. Press it over a tailor's ham, which mimics the curve of the body, so the seam keeps its shaped form. Set the seam first by pressing along the stitching line, then press the allowances open or to one side over the ham.

Pressing on the flat is the second most common cause of a poor princess seam after wrong clipping. The ham lets the fabric mold to the intended curve, and a shot of steam sets that curve permanently into the cloth.

Once pressed, grade the seam allowances if the fabric is bulky, trimming one narrower than the other so the enclosed seam does not press through as a ridge on the right side. On a lined jacket the allowances are usually pressed open; on an unlined garment they may be finished together and pressed to one side, most often toward the side panel.

Finish the raw edges according to the garment, but avoid heavy finishing on a fine fabric where it would show through. The aim is a seam that is secure and clean inside while remaining smooth and invisible in its shaping outside.

A princess seam only fits if the curve is positioned correctly over the bust, which is a matter of the pattern rather than the sewing. If the seam's fullest point sits above or below the actual bust point, no amount of careful stitching will make it sit smooth. Minerva Patterns supplies made-to-measure patterns in DXF AAMA, PLT and PDF generated from individual measurements, so the princess seam curve is placed over the wearer's own bust point, which is what makes the shaping land correctly.