Sewing a hem with a twin needle for polished results

A twin needle is one of the simplest ways to give handmade garments a neat, ready-to-wear finish. It creates two parallel lines of stitching on the right side, while the bobbin thread forms a flexible zigzag underneath. This makes it especially useful for T-shirts, knit dresses, leggings, cuffs and casual tops.

The technique works well with many indie sewing patterns, including the relaxed knit styles often featured by Love Notions. With the right needle, thread, tension and preparation, you can achieve a clean hem at home without investing in a coverstitch machine. The result is tidy enough for everyday wear and durable enough for repeated washing.

Choose the right needle and thread

Twin needles are available in different widths and types. For most stretch garments, begin with a 75/4 or 75/3 stretch or jersey twin needle. The first number refers to the needle size, while the second indicates the distance between the needles in millimetres. A 4 mm spacing gives a familiar double row, while a narrower 2.5 or 3 mm option can suit lightweight fabrics and smaller hems.

Use two reels of the same ordinary sewing thread for the needle threads, with a bobbin wound from that thread. Polyester thread is a reliable choice because it has some give and tolerates regular laundering. Avoid using heavy topstitching thread through both needles unless your machine specifically supports it; it can create excess bulk and tension problems.

Check the needle package before sewing. A twin needle designed for woven fabrics may have a sharp point, while a stretch twin needle has a rounded point that is less likely to damage jersey. If you are working with sequins, metallic coatings or embellished cloth, change your approach entirely and protect the machine first by reading these tips for sewing with sequined fabric.

Prepare the hem before stitching

Press the hem allowance accurately before bringing the garment to the machine. For a knit, a double fold of around 2–3 cm is common, although the pattern instructions should take priority. A narrow hem may be preferable on lightweight bamboo jersey, while a deeper fold adds weight and stability to a sweatshirt hem.

If the fabric curls, use a warm iron with a pressing cloth and avoid stretching the edge. A little spray starch can help on stable knits, but test it on a scrap first. Washable glue stick, temporary fabric tape or a few well-placed pins can hold a troublesome fold in place. In Australia’s humid summer weather, some viscose knits relax after pressing, so let the hem cool and settle before measuring it again.

Always sew a test sample using the actual fabric, folded in the same number of layers as the garment. Test on scraps left from cutting rather than a single layer, since the hem’s thickness affects stitch formation. This is particularly important with fabrics purchased from Spotlight, Lincraft or smaller online Australian shops, where the same fibre content can behave very differently depending on the knit structure.

Set up the machine correctly

Insert the twin needle with the flat side facing the correct direction for your machine, then thread it carefully. Each needle thread should pass through the usual guides, but do not force both threads through a single needle eye. If your machine has two spool pins, place one reel on each. Otherwise, use a thread stand, a small cup beside the machine or two reels positioned so they unwind smoothly without catching.

The bobbin is threaded normally. Select a straight stitch and begin with a medium length, usually around 2.5–3.5 mm. Lower the presser foot and turn the handwheel towards you to check that both needles clear the foot and needle plate. A standard zigzag foot may be suitable if the needle fits through its opening, but a straight-stitch foot is unsafe because the needles can strike the metal.

Reduce the presser-foot pressure if your machine allows it, especially with soft jersey. Do not pull the fabric from behind as you sew. Guide it gently and let the feed dogs move it at a steady pace. For a hem on a Love Notions knit pattern, sewing from the right side usually makes it easier to keep the double row an even distance from the folded edge.

Fabric or project	Needle choice	Starting stitch settings	Helpful adjustment
Lightweight cotton jersey	75/3 stretch twin	2.5–3 mm length	Use a narrow hem and light pressure
Medium-weight T-shirt knit	75/4 stretch twin	3–3.5 mm length	Stabilise the fold if it rolls
Rib knit or very stretchy fabric	75/4 stretch twin	3 mm length	Sew slowly and avoid stretching
Woven cotton hem detail	80/4 universal twin	2.5–3 mm length	Press firmly and test for puckering
Thick sweatshirt fleece	90/4 stretch twin	3.5–4 mm length	Use a deeper hem and longer stitch

Sew a steady, even double row

Place the garment under the presser foot with the folded edge positioned so the twin needle stitches sit just inside the hem allowance. The outer needle should remain on the garment body while the inner needle runs near the fold. On the first few centimetres, keep your eyes on the fabric edge rather than the needles; a marked line or seam guide can help maintain an even distance.

Lower the needle into the fabric before starting. Sew slowly for the first stitches, especially around side seams where several layers meet. If the machine struggles over a bulky join, use a hump jumper, folded scrap or height compensation tool to keep the presser foot level. At the end, leave thread tails long enough to pull to the underside and secure by hand, or use a very small amount of fabric sealant if appropriate for the fabric.

The twin needle will naturally create a zigzag on the wrong side. That movement provides the stretch needed for many knit hems, but it is not unlimited. If the garment hem must stretch significantly when pulled over the body, a coverstitch, narrow zigzag or stretch stitch may be more suitable. A twin needle gives a polished appearance, but the finished seam still needs to match the demands of the garment.

For long hems, sew in manageable sections and stop with both needles down when adjusting the fabric. This prevents the layers shifting. A circular hem, such as the bottom of a knit dress, may need careful easing to prevent tiny tucks. If the circumference is longer than the garment edge, distribute the excess before stitching rather than trying to push it under the foot.

Fix common problems and care for the finish

Tunnelling occurs when the fabric rises between the two rows of stitching. It is common on fine jersey and can usually be reduced by lowering the upper thread tension, lengthening the stitch or adding lightweight knit interfacing to the hem allowance. Wash-away stabiliser placed beneath the hem can also support delicate fabric during sewing and disappears after laundering.

Skipped stitches often point to the wrong needle type, a blunt needle, incorrect threading or excessive stretching while sewing. Replace the needle, rethread both paths and test again. If the thread breaks, check for a burr on the needle plate, rough thread guides or tension set too tightly. A fresh needle is inexpensive insurance, particularly when sewing garments intended for the harsh Australian sun and frequent washing.

Wavy hems can result from stretching the fabric, a high presser-foot pressure or feed problems. Let the fabric recover, press the finished hem with steam and allow it to cool flat. If the edge remains distorted, a narrow strip of fusible stay tape inside the allowance can stabilise it. Before washing the completed garment, follow the pattern’s care advice and allow shrinkage for fabrics that were not prewashed.

Keep a small record of the successful settings for each fabric type. Notes such as “75/4 stretch twin, 3 mm stitch, tension 2.5” can save time when working through several garments in a season. If you publish project photographs or join an online sewing group, avoid sharing personal details such as addresses or private order information; the site’s privacy policy explains how personal data should be handled online.

A well-prepared hem, a compatible needle and a calm sewing pace make the greatest difference. Once the test scrap looks balanced on both sides, the final garment should have two smooth rows on the outside, a flexible zigzag underneath and a finish that looks deliberately made rather than improvised.