How to sew knits on a regular sewing machine without an overlocker

An overlocker is handy, but knits can be sewn neatly and strongly without one. Here is which needle and thread to use, which stitches of a regular sewing machine stretch with the fabric and how to finish hems, necklines and armholes.

How knit differs from woven fabric

Ordinary fabric is woven: warp and weft threads cross at right angles and barely stretch. Knit fabric is made of loops that stretch and then return to place. Every peculiarity of sewing knits follows from this. Knit stretches, so the seam has to stretch with it. The loops are easily damaged by a sharp needle, so the needle needs a rounded point. And the edge of most knits does not fray the way woven fabric does, so it does not have to be finished: for knits an overlocker is a convenience rather than a necessity.

On the other hand, a knit edge often curls, especially on thin fabric. It is not a defect but a property of the knit structure: to keep the edge out of the way, hold it down lightly with your fingers in front of the foot or sew with a thin strip of paper underneath.

Why a straight stitch breaks

Knit fabric stretches and a straight stitch does not. When the garment is pulled on or stretched, the thread in a straight seam snaps. Knits therefore need stitches with spare length: zigzag, triple stretch stitch or a twin needle.

Top to bottom: straight stitch (breaks when stretched), narrow zigzag, triple stretch stitch, twin-needle hem.

Needle, thread, settings

• Needle: jersey (ballpoint) or stretch, size 75-90. A sharp universal needle cuts the loops of the knit and skips stitches.
• Thread: polyester, it stretches a little; cotton breaks.
• Presser foot pressure: lower it if your machine allows, or use a walking foot, so the layers do not shift and the seam does not wave.
• Do not pull the fabric while sewing, only guide it.

Before you sew

• Sew a test seam on a scrap of the same fabric, folded in two layers as in the garment. Stretch it: if the thread breaks or the seam does not stretch, change the stitch or the tension.
• Pin only within the seam allowance or use sewing clips: on thin knits pin marks may show on the right side.
• Mark the direction of greatest stretch on every piece so you do not mix it up when assembling.
• Seam allowances of 0.7-1 cm are enough: knits do not need wide allowances, and narrow ones are easier to finish with zigzag.

Which stitch to use

• Narrow zigzag (width 1-1.5 mm, length 2-2.5 mm) for joining seams, then a wider zigzag along the seam allowances so they lie flat.
• Triple stretch stitch (on many machines shown as three parallel lines) is very strong, good for side and shoulder seams of leotards and leggings.
• Overlock-type stretch stitch, if your machine has one: sews and finishes the edge at the same time.
• Twin needle for hems of the bottom and sleeves: two straight lines on top, a zigzag underneath, and the hem stretches with the garment.

Hemming without a twin needle

• Zigzag hem. Turn up the edge by 1.5-2 cm and stitch from the right side with a medium zigzag: the hem stretches and is barely visible.
• Lettuce edge. A wide, dense zigzag right on the edge while stretching the fabric hard in front of the foot: the edge curls into a wave. It looks lovely on skirts, sleeves and dance leotards.
• Raw edge. Biflex and most synthetic knits do not fray, so the hem of leggings or a skirt can simply be cut straight.

How to sew on elastic

Join the waist or leotard elastic into a ring, divide it and the garment edge into four equal parts and pin the marks together. Sew with a zigzag or three-step zigzag, stretching the elastic to the length of the edge between the marks but not stretching the fabric itself. Then fold the elastic to the inside and topstitch again with zigzag from the right side: this way it will not twist in the waistband.

Neckline, armholes, shoulders

• Necklines and armholes are finished with a binding of the same knit, cut across the greatest stretch and slightly shorter than the opening, or with elastic.
• Shoulder seams are stabilised with thin tape or clear silicone elastic so they do not stretch out.

Order of assembly: a leotard as an example

1. Sew the shoulder seams with triple stretch stitch, stabilised with tape.
2. Finish the neckline with binding while the garment still lies flat: it is easier that way.
3. Set in the sleeves, if any, or finish the armholes with binding or elastic.
4. Sew the side seams in one pass from sleeve hem to garment hem.
5. Finish the leg openings with elastic and the sleeve hems with zigzag or a twin needle.

Sew so that every seam crosses one that is already finished: the seam ends are then secured by themselves and do not unravel in wear.

When something goes wrong

Pressing

Synthetic knits are pressed at a low temperature, through a thin cloth and without pressure: the iron only touches the seam rather than gliding along it, or the fabric will stretch. Metallic fabrics (disco, holographic, lurex) are pressed on the wrong side only. Often a light steaming from a distance is enough: steam evens out wavy seams and gives the fabric its shape back.

Frequently asked questions

Do I need a special machine for knits?

No. Any domestic machine with a zigzag can sew knits, as long as you fit the right needle and lower the presser foot pressure.

Does a zigzag hold as well as an overlock seam?

For everyday clothes and leotards, yes: a narrow or triple zigzag withstands stretching and washing. An overlocker gives a neater inside and sews faster, but on ordinary garments the difference in strength is small.

Which thread for metallic fabrics?

Ordinary polyester thread in the colour of the base. Metallic threads are not needed for seams: they are stiff, stretch less and break more often, and the seam is hidden in the allowances anyway.

Which fabrics

All our stretch fabrics are sewn this way: biflex, disco, holographic, lurex and Italian velvet. Sew metallic fabrics with a new needle: the coating blunts it quickly. To choose a fabric for a garment, see our overview «Knits, satin and mesh», and to cut a leotard, our biflex article.