Threads Contributing Editor Kenneth D. King explain show to handle princess seams in heavy fabrics, so the seam is smooth and the seam allowances don’t add bulk.

When sewing princess seams, you can press the allowances open or press both to one side, depending on the garment and the fabric. In heavier fabrics, pressing the allowances open balances the bulk on both sides of the seamline, so this is the preferred method. Kenneth also recommends not clipping or notching the seam allowances. Although most pattern instructions tell you to do so, he avoids cutting into the allowances so there is intact seam allowance width in case the garment needs to be let out later.

Prepare the seam allowances

Instead of clipping the allowances on the concave center panel seam, Kenneth uses a steam iron to stretch the allowance. Avoiding the seamline, press and stretch just the allowance edge until it is the same length as the side panel’s edge. This enables you to sew the princess seam easily.

You’ll also need to ease the side panel’s allowance so that, once the seam is sewn, this longer allowance can be pressed flat to the garment. Kenneth demonstrates his method for applying easestitching to the seam allowance.

Press the seam

After sewing the seam, press it as sewn. Then press the allowances open over a ham. The center panel’s prestretched allowance should fold flat to the garment, but if necessary, stretch it with the steam iron. Do the same for any concave curves below the bust level. On the side panel’s allowance, pull the easestitching bobbin threads and shrink-press the allowance flat. Press the seamline, allow to cool, then remove the easestitching.

This technique ensures a smooth seam that gracefully shapes your garment, with no unsightly…