Cotton flannel is a soft, brushed plain or twill weave that is easy to sew and kind to beginners, with one serious habit: it shrinks, often 5 to 10 % in length, and shrinks a little more on the second wash. Pre-wash it twice on the hottest cycle you will ever use, cut every piece in the same direction because the brushed surface has a nap, sew with a universal 90/14 needle at 3 mm, and finish the seams, because the loose weave frays. Press from the wrong side on the cotton setting so the nap is not flattened.
Quick reference: how to sew cotton flannel
| Setting | Recommendation |
|---|---|
| Needle | Universal 80/12 for shirt-weight, 90/14 for heavy flannel |
| Thread | Polyester or cotton all-purpose |
| Stitch length | 2.5 to 3 mm; 3 to 3.5 mm for topstitching |
| Presser foot | Standard; walking foot for plaids and bulky seams |
| Pre-wash | Yes, twice, warm or hot wash and tumble dry |
| Pressing temperature | Cotton setting, about 200 °C (390 °F), steam, from the wrong side |
| Seam finish | Overlock, zigzag or flat-felled; French seams on light flannel |
This post is about cotton flannel, the fabric of pajamas, shirts and baby blankets. Wool flannel is a different cloth with its own rules, covered in sewing with wool.
What is flannel, and why does it shrink so much?
Flannel is a cotton fabric, plain or twill woven, that is brushed with fine wire rollers after weaving to raise a soft nap on one or both sides. The brushing is what makes it warm: the raised fibers trap air. It is also why it behaves the way it does. The weave is usually loose and the yarns are soft and low-twist, so the cloth relaxes dramatically the first time it is washed and tumble-dried. Flannelette and brushed cotton are lighter versions of the same idea.
Weights run from about 120 g/m² (3.5 oz/yd²) for shirting and sheeting flannel to 200 g/m² (6 oz/yd²) and more for heavy shirt and blanket flannel. Quilting-shop flannel is often 110 cm (44 in) wide; shirting flannel comes in 140 and 150 cm (55 and 60 in). If your pattern gives quantities for several widths, as Sewly's sewing guide does for 110, 140 and 150 cm, pick the width you are buying and add 10 to 15 % to it for shrinkage and the nap layout, and 20 % for a plaid that must match.
How should you pre-wash flannel?
Wash it the way the garment will be washed, and then do it again. Most of the shrinkage happens on the first wash and dry, but a second cycle usually takes out another 1 to 2 %, which is enough to shorten a pair of pajama trousers by a visible amount. Warm or hot water, a normal spin and a tumble dry on medium are what pajamas will get, so that is the test to give the fabric.
Flannel sheds a lot of lint in the first washes. Wash it alone or with towels, clean the lint filter, and expect fluff in the machine's bobbin area later as well. The raw edges fray in the wash; zigzag them or trim them with pinking shears first, or accept a tangle of threads to cut away. Fabric shrinkage by fiber puts flannel's 5 to 10 % next to other cottons.
After drying, flannel is often off-grain: the brushed weave distorts and the plaid lines run at an angle. Fold it selvage to selvage and check that the crosswise lines meet the fold at a right angle; if they do not, pull the fabric diagonally from the short corners until they do, then press.
How do you cut flannel with the nap?
Brushed cotton has a direction, like velvet or corduroy but much subtler. Stroke it: one way is smooth, the other slightly rough, and the color looks a shade different in each. Lay out every pattern piece with its top pointing the same way, the "with nap" layout, or one trouser leg will look lighter than the other in daylight. For double-brushed flannel this matters less, but keep the habit.
Plaids and checks are the other cutting job. Cut a single layer, lay each piece on the same stripe at the hem and the side seams, and cut the second copy by placing the first, cut piece face down on the fabric with the lines matched underneath. How to match plaids and stripes explains where to match and where no one will look. Use long, sharp pins or clips; flannel grips itself and rarely slides, which is one of the reasons it suits beginners.
Which needle, thread and stitch length suit flannel?
A universal 80/12 is right for shirt-weight flannel, and a 90/14 for heavy or double-brushed cloth, where a thinner needle deflects and skips stitches. Flannel dulls needles faster than smooth cotton, so change it after each big project. Polyester all-purpose thread is the default; cotton thread matches the fabric's softness for pajamas and quilts. Set the stitch length to 2.5 mm for shirting and 3 mm for heavier flannel, and 3 to 3.5 mm for topstitching, where a short stitch disappears in the nap.
The brushed surfaces of two layers tend to creep against each other over a long seam, so the top layer arrives at the end a few millimeters behind. Pin more often than you would on poplin, or fit a walking foot, which also keeps plaids matched as you sew. Clean the lint from under the needle plate every few hours of sewing.
How should you finish seams in flannel?
The loose weave frays, and the seams are inside clothes that are washed often, so finish every one. A serger or a zigzag 2 mm wide and 1.5 mm long is quick; the seam finishing guide covers the alternatives. For pajamas and shirts, the flat-felled seam is the traditional choice: strong, flat and smooth against the skin, with no raw edge anywhere. French seams work on light flannel and on children's clothes but add bulk in anything heavier. Trim seam allowances to 1 cm (3/8 in) at crossings and grade them in collars and cuffs, because flannel on flannel builds thickness fast.
How do you press flannel?
Flannel takes a hot iron and steam, but press it from the wrong side, or through a pressing cloth from the right side, so the nap is not flattened into a shiny patch. Press seams open or to one side, lifting the iron rather than dragging it, and let the fabric cool before you move it. Fusible interfacing bonds well to the wrong side; use a light or medium weight and a press cloth, and give it the full time with pressure, since the nap keeps the glue a little away from the yarns.
How do you hem flannel?
A double-fold hem is the natural finish: fold 1 cm (3/8 in), then 2 cm (3/4 in), and topstitch at 3 mm. On trousers and robes, 2.5 to 3 cm (1 to 1 1/4 in) looks better and adds weight that keeps the hem down. Shirt hems with a curve take a narrow 1 cm double fold. Because the nap hides stitches, a machine blind hem works well on flannel skirts and dresses. How to hem shows the folds and the feet. Allow for a little further shrinkage even after two washes: a hem on the generous side is easy to adjust later.
What should you sew with flannel?
- Pajama trousers and shorts: the classic flannel project, and a good first garment. Pull-on trousers with an elastic waist have no fitting to worry about, and the pull-on shorts version uses less than a meter (yard).
- A shirt or an overshirt: a button-front woven top in shirting flannel, cut with the nap and the plaid matched at the front, with flat-felled seams for the full lumberjack effect.
- A robe-style kimono jacket or cushion covers: a kimono jacket in heavy flannel is a house coat, and a cushion cover in a plaid flannel is an evening's work and a good way to use the offcuts.