How do I sew neat corners and curves?

Corners and curves are where the difference between a home-made and a bought-looking item is most visible, and both come down to the same idea: fabric that has to turn a corner or a curve has to either lose or gain length in the seam allowance, and the technique is about managing that.

What you'll need

• Small sharp scissors, ideally embroidery scissors
• A point turner, or a blunt knitting needle or chopstick
• An iron

Step by step

1. Sew corners by pivoting with the needle down.Slow to a handwheel as you approach, and stop with the needle right down in the fabric at the exact corner point. Lift the presser foot, swivel the work round the needle, lower the foot, and carry on. The needle is the pivot, which is why it must be down.
2. Mark the pivot point in advance on anything precise.A chalk dot where the two seam lines cross. Judging it by eye at speed is the reason corners come out rounded or overrun.
3. Take one stitch across the corner on anything turned out.On a cushion, a bag or a collar, sew to a stitch short of the corner, pivot, take one diagonal stitch across the corner, pivot again, and continue. That one stitch creates room for the bulk of fabric that has to fit inside the turned point. On heavy fabric, take two.
4. Trim the corner before turning.Cut across the corner close to the stitching — about 3mm away — and taper the two allowances either side. All the bulk you leave in there is bulk that has to fit inside the point, and it is why unturned corners look blunt and lumpy.
5. Turn corners out with a blunt tool.A point turner, a chopstick or the eye end of a knitting needle. Never scissors or a pin: a sharp point pushes straight through the corner and there is no repairing it.
6. Shorten the stitch on curves.About 2mm. A short stitch approximates the curve in smaller straight segments, which is what makes it look smooth, and it strengthens a seam whose stitches are all slightly off the line of pull.
7. Steer curves in small corrections, not one turn.Sew slowly and make many small adjustments to the direction of the fabric. Stopping to pivot on a curve leaves visible flats.
8. Clip inward curves.A concave curve — the inside of a neckline, an armhole — has too little fabric in the allowance to open out when turned. Cut small snips into the allowance, perpendicular to the seam, up to about 2mm from the stitching. That lets the allowance spread.
9. Notch outward curves.A convex curve — the outside of a collar, a pocket flap, a rounded hem — has too much fabric in the allowance, which bunches when turned. Cut small wedges out of the allowance so the excess can close up. Notch more often on a tighter curve.
10. Grade the allowances on anything with layers.Trim the two allowances to different widths so the seam steps down rather than making a ridge. On a collar or a facing this is what stops a hard line showing through on the right side.
11. Press over a curved surface.A tailor's ham, or a rolled-up towel. Pressing a curved seam flat on a flat board presses the curve out of it.

Tips

• Reinforce before you clip anything you are cutting close to — a second row of stitching just inside the first on a tight inward curve stops the clips reaching the seam.
• On a very tight curve, sew, then clip, then press before turning. Turning first and clipping afterwards is much harder to do accurately.
• For repeated identical corners, such as on a set of cushion covers, mark all the pivot points before you start sewing anything.
• Very thick fabric will never give a sharp point. Accept a slightly softened corner rather than trimming so close that the stitching lets go.

Common mistakes

• Lifting the presser foot with the needle up to pivot — There is nothing holding the fabric, so it shifts, and the corner comes out rounded or offset. Needle down, always.
• Cutting clips right up to the stitching — It leaves nothing holding the seam, and the clip opens into a hole under tension. Stop 2mm short, and reinforce first on a tight curve.
• Poking a corner out with scissors — It pushes through the fabric between the stitches and leaves a permanent hole exactly at the point where it is most visible.
• Notching an inward curve and clipping an outward one — It is the wrong way round. Inward curves need to spread, so they get clips. Outward curves need to shrink, so they get wedges removed.

If it doesn't work

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