Sewing with scuba (neoprene-look) knit

Scuba is a smooth, spongy polyester and elastane double knit that looks like neoprene and stands away from the body instead of draping. Sew it with a 75/11 to 90/14 stretch needle, polyester thread, a 3 mm (1/8 in) stitch, a walking foot, and no seam finish, because the cut edge does not fray. Keep the iron on the synthetic setting with a press cloth, since polyester glazes, and let the fabric's body do the work in full skirts and structured dresses.

Quick reference: how to sew scuba

What is scuba fabric, and is it the same as neoprene?

Neoprene is a sheet of synthetic rubber, usually laminated between two thin knits; it is the material of wetsuits. Scuba borrows the look and the spring but is a knit alone: a polyester or polyester-elastane double knit of 250–400 g/m² (7–12 oz/yd²), with a smooth face, a fine, spongy hand and no rubber layer. It stretches 30–50 % across the grain and usually along it too, recovers almost completely, does not fray and does not crease. Scuba crepe has a pebbled face and a little less body; it sews the same way.

Because it is polyester, scuba holds heat and does not breathe much. It suits cool-weather garments, evening and party clothes and anything meant to hold a shape, more than a summer dress. Its stability also means it is cut close to the body measurements rather than with the strong negative ease of a jersey: 0–2 cm (0–3/4 in) at the hip is enough for a fitted skirt.

Do you need to pre-wash scuba?

Polyester does not shrink, so scuba needs no pre-shrinking. Wash it anyway before cutting, on a cool, gentle cycle, to remove finishing residues and to see how the surface behaves, then line or flat dry. Never tumble it hot: the heat sets creases and dulls the face.

How do you cut scuba?

Scuba is thick but cooperative: it does not slip or curl, and it cuts cleanly.

• Fold it selvage to selvage, or cut a single layer for a heavy scuba so the two halves come out identical.
• Use pattern weights and a sharp rotary cutter. Pins leave visible holes in some smooth scubas, so if you pin, stay inside the seam allowance.
• Mark the wrong side of each piece with chalk. Many scubas have a slightly shinier face; pick one and keep it consistent.
• Lay the greatest stretch around the body. On a two-way-stretch scuba the difference is small, but the grainline still runs along the length.
• Mark darts and dots with chalk or a washable marker, never a tracing wheel: the wheel's teeth leave permanent marks.

Which needle, thread and stitch work on scuba?

A stretch needle slides between the loops without cutting them. A 75/11 suits a 250 g/m² scuba; a 90/14 pushes through the heavy ones without bending. Skipped stitches on scuba almost always mean a worn or wrong needle, so change it first.

Most seams in a scuba skirt or dress are not under much stretch, and a straight stitch at 3 mm works. For a seam that must stretch, such as the side seam of a pull-on pencil skirt, use a 1 mm × 3 mm zigzag or the lightning stitch. A 4-thread overlock with the differential feed at 1.0 is the fastest; raise it a little if the edge waves. The spongy layers shift against each other under a standard foot, so the top layer creeps and the seam ends do not match. A walking foot feeds both layers evenly; reducing the presser-foot pressure helps if you do not have one.

How do you press scuba?

Scuba does not take a crease, which is good news for a skirt and bad news for seam allowances. Press on the synthetic setting with a press cloth and light steam, lower and lift, and let it cool. The allowances will not stay open on their own: finger press them, then topstitch 6 mm (1/4 in) each side of the seam line, or edgestitch both allowances to one side. The topstitching holds the seam flat and reads as a design line on the smooth face. A strip of fusible knit tape under each allowance is the alternative when you want no visible stitching. Never put the iron on the right side without a cloth: polyester glazes, and the shine does not come out. How to press seams properly has the general rules.

How do you finish seams and hem scuba?

The cut edge is the finish. Trim the allowances to 6 mm (1/4 in) on curves to reduce bulk, and leave straight seams as they are.

For hems, a raw edge is standard in scuba: cut the hem line with a rotary cutter against a ruler and it stays sharp through washing. On a circle skirt this is the cleanest finish and the only one that does not fight the curve. Where you want a visible hem, fold once by 2 cm (3/4 in) and topstitch with a straight stitch at 3.5 mm, or a twin needle if the hem has to stretch, as on a fitted skirt. Skip double-fold hems: three layers of scuba make a stiff, rippling band. How to hem explains the single-fold and narrow hems in detail.

Necklines and armholes follow the same logic. A self-fabric facing is thick; a binding cut from a lighter knit, a narrow turn-and-stitch, or a clean raw edge is lighter and sits better.

Common mistakes with scuba

• A hot iron. Glazing, and in the worst case a melted patch.
• Deep or double-fold hems. Too much bulk; keep hems single and narrow, or raw.
• Jersey-style negative ease. Scuba stretches, but it is firm; cut close to the body, not well under it.
• Self-fabric facings. Use a lighter fabric or a binding.
• A standard foot on a long seam. The top layer creeps and the hem ends up uneven.

What to sew with scuba

Scuba is for shapes that stand away from the body and hold a line.

• A circle skirt in scuba is the classic use: a full or three-quarter circle flares like a 1950s skirt without a petticoat, and the raw-edge hem keeps the curve clean. Let it hang overnight anyway; it drops less than a woven but it does drop.
• A fit-and-flare dress with a half-circle skirt gets a sculpted bodice and a skirt that swings. Sewly drafts it with a 1 cm (3/8 in) seam allowance on knits, the allowance scuba likes.
• A pencil skirt in scuba pulls on with an elastic waist, holds its shape over the hips and needs no lining.