How to Sew a Bias Edge
Sew a sturdy binding even on your most delicate garments with this technique by Susan Crane. This bias edge is lightweight enough to use on chiffon and sturdy enough to hold armhole and neckline shapes. This works with most fabrics, but you’ll discover that a fabric takes curves better if it has a little give.
On a curve, especially an armhole, fabric is shorter in the seam allowance than on the seamline, so if you turn the edge under to finish it, the outer edge will pucker. So I trim the seam allowance to almost nothing (1/8 inch), and if the fabric is unusually stable, I relax it by carefully clipping into the tiny seam allowance.
To bind an armhole, you sew the shoulder seams and side seams, and then bind the armhole “in the round”. Binding the armhole while it’s still flat is faster, but sewing in the round makes a neater finish at the side seam.
From Threads #145