Sewing with twill: trousers, jackets and bags

Twill is any fabric woven with a diagonal rib, and the cotton twills used for trousers, jackets and bags (chino, drill, stretch twill, gabardine) are medium to heavy, stable and easy to sew. Use a universal or jeans needle in 90/14 (100/16 above about 300 GSM), all-purpose polyester thread, a 3 mm stitch and a standard foot, pre-wash because cotton twill shrinks 3–5%, press hot with steam and a press cloth, and finish seams by serging, binding or flat-felling. The one thing to watch is the direction of the diagonal: cut every piece the same way up.

Quick reference: how to sew twill

What is twill and which twills are good for garments?

Twill is a weave, not a fiber. The weft passes over two or more warp threads and the step shifts by one on each row, which draws the diagonal line you see on the surface. That structure makes twill denser and more supple than a plain weave of the same weight, more resistant to wrinkles, and gives it a definite right side: the diagonal is clearer there, usually running from bottom left to top right.

The twills you will meet in a fabric shop:

• Chino twill (200–260 GSM, 6–7.5 oz/yd²): the classic trouser fabric, soft after washing.
• Cotton drill (260–340 GSM, 7.5–10 oz/yd²): a steeper, denser twill for workwear, jackets and bags.
• Stretch twill: chino with 2–3% elastane, comfortable in tapered and slim trousers.
• Gabardine: a tight, steep twill in wool, polyester or a blend, for trousers and raincoats; it shows needle holes and dislikes heavy pressing.
• Tencel and viscose twill (150–200 GSM): drapey and fluid, cut on the bias for dresses; sew it as you would viscose.
• Denim: a twill with a dyed warp and white weft, covered in its own post.

The trouser fabrics comparison puts twill next to linen, Tencel and ponte if you are choosing for a specific pair.

Should you pre-wash twill?

Yes, and dry it the way the garment will be dried. Cotton twill shrinks 3–5%, which is 4–5 cm (1 1/2–2 in) on a 100 cm (39 in) trouser leg, and it shrinks more along the length than across. Wash it twice if you plan to tumble dry the garment. Wool gabardine should go to the dry cleaner or be steamed thoroughly instead. After washing, press the fabric flat while it is still slightly damp; creases in dry twill are stubborn.

How do you cut twill?

The diagonal is the thing. Plain cotton twill has no pile, but the diagonal line reflects light differently in each direction, and some twills are brushed on one side. Treat it as a fabric with nap and lay every piece the same way up; a trouser leg cut head to toe next to one cut toe to head can look like two shades of the same color.

• Fold selvage to selvage with the right side in, line up the diagonal and check that the fold lies flat; a skewed fold means the fabric is off grain.
• Use weights and a rotary cutter, or sharp shears; twill is heavy enough that pins distort the layers when you lift them.
• Mark the wrong side of each piece with a chalk cross, because the diagonal is faint on light twills and pieces get turned over on the table.
• Cut waistbands and belt loops on the lengthwise grain, where twill stretches least.

How do you sew twill, especially at thick seams?

Seams in twill are easy on the flat; the trouble comes where seams cross and at hems, where you can be sewing through six or eight layers. A few habits make the difference:

1. Match the needle to the weight. 90/14 universal for chino and stretch twill (or a 90/14 stretch needle for a high elastane content), 100/16 jeans for drill and anything over about 300 GSM. A needle that is too thin deflects at a thick crossing and breaks.
2. Lengthen the stitch to 3 mm. Short stitches pack thread into a dense fabric and the seam puckers.
3. Grade the seam allowances where seams cross: trim one layer to 6 mm (1/4 in) so the bulk steps down instead of piling up.
4. Level the foot over thick seams. Fold a scrap of twill and slide it behind the foot (or use a hump jumper) so the foot sits flat as it climbs the seam; otherwise the stitches shorten and the needle can jam.
5. Topstitch with a longer stitch. 3.5 mm, with topstitching thread on top and all-purpose thread in the bobbin, and a 100/16 topstitch needle whose larger eye stops the heavier thread from shredding.
6. Use a walking foot for bags. When you sew a tote in drill, the walking foot feeds the top and bottom layers together so the handles and seams come out even.

For trousers, a flat-felled seam on the inside leg looks like ready-to-wear and wears for years; on the outside leg a serged, pressed-open seam is flatter under a pocket. The waist of pull-on trousers takes a 3–4 cm (1 1/4–1 1/2 in) elastic in a casing folded down from the trouser fabric itself.

How do you press twill?

Hot and wet. Set the iron to cotton, use plenty of steam, and press each seam flat first, then open. On dark twill protect the surface with a press cloth, because the dense diagonal weave picks up shine quickly. Flatten bulky seams with a clapper: steam the seam, then hold the wooden block on it for ten seconds as it cools, and the seam stays flat. Gabardine is the exception: press lightly through a cloth, because its surface marks and glazes.

How do you hem twill?

Trousers and shorts take a 3 cm (1 1/4 in) double-fold hem, pressed and topstitched 2.5 cm (1 in) from the edge, or a blind hem if you prefer it invisible. On drill and heavy twill reduce the bulk by finishing the raw edge with a serger or bias tape, folding once by 3 cm and topstitching. For jackets and aprons a 2 cm (3/4 in) double fold is enough. Press the hem over a seam roll so the seam allowances inside do not print through to the right side.

What should you sew with twill?

• Pull-on trousers with a straight or tapered leg: a 220–260 GSM chino twill with 2% elastane keeps the knees from bagging. The same fabric makes sturdy pull-on shorts.
• A kimono jacket in a soft, washed chino twill: the simple shape suits a fabric with some body, and the seams can be bound for a clean inside.
• A tote bag or apron in drill: heavy enough to stand up, lighter and easier to sew than canvas.