Making and Applying Bias Binding for Curved and Straight Edges

The true bias runs at forty-five degrees to both the lengthwise and crosswise grain, and it is the direction in which woven fabric has the most give. That stretch is what allows a binding to be coaxed around a concave neckline or a convex armhole and still sit smooth, because the strip can lengthen along its outer edge and compress along its inner edge.

A strip cut on the straight grain has almost no give and will buckle the moment it meets a curve. This is why binding intended for anything but a dead-straight edge must be cut on the bias, without exception.

Find the bias by folding the fabric so the crosswise grain aligns with the lengthwise grain; the diagonal fold is the true bias. Mark and cut parallel strips along that direction. Strip width is usually four times the finished width for double-fold binding, or twice the finished width plus seam allowances for single-fold.

Join strips end to end with a diagonal seam, not a straight one, so the join is distributed across the width and does not stack into a lump. Place two strip ends right sides together at a right angle, stitch across the diagonal, trim the allowance and press it open. A continuous-loop method can produce yards of binding from a single square with just two seams.

• Single-fold binding: both raw edges pressed to the center, used where one layer of coverage is enough or bulk must be minimal.
• Double-fold binding: folded again down the middle, giving a sturdier, fully enclosed finish ideal for edges that take wear.
• Bias facing: binding turned fully to the inside so nothing shows on the right side, for an invisible edge finish.
• Bound edge as decoration: contrast binding left visible on the right side as a design feature.

1. 1.Open one fold of the binding and pin its raw edge to the garment edge, right sides together.
2. 2.Gently ease, not stretch, the binding around convex curves and let it relax around concave ones.
3. 3.Stitch in the pressed crease, keeping the seam allowance even.
4. 4.Turn the binding over the raw edge to the wrong side, enclosing it fully.
5. 5.Stitch in the ditch or slipstitch the folded edge down, checking it catches on the underside.

At an outward corner, stop stitching a binding width from the edge, fold the binding back on itself to form a miter, then continue down the next side. The mitered fold distributes the excess neatly instead of bunching it. Inner corners are clipped into the garment allowance so the edge can open out straight for binding.

Close the binding loop with a diagonal join rather than overlapping raw ends. Overlaps create a hard bump; a bias join blends into the run of the binding and is nearly invisible once pressed.

Lightweight, tightly woven fabrics such as fine cotton lawn or lightweight poplin make the best binding, folding crisply without adding bulk. Heavier fabrics work for decorative bound edges but become unwieldy on tight curves. Match the binding fiber to the garment where possible so the two behave the same in laundering.

Where a pattern calls for a bound finish, the edge length and curve are defined by the piece itself. Minerva Patterns supplies made-to-measure patterns in DXF AAMA, PLT and PDF, so you can measure the exact neckline or armhole run and cut the right length of binding before you begin.