Woven, Knit, and Nonwoven Structures Explained

Fibre content tells you how a fabric behaves under heat and water. Structure tells you how it behaves under tension, which is the property you are relying on every time you match a fabric to a pattern. There are three ways to turn yarn or fibre into cloth, and they produce genuinely different materials.

Wovens: two yarn sets crossing at right angles

A woven fabric is made from warp yarns running the length of the cloth and weft yarns crossing them. The pattern in which they interlace is the weave. ISO 3572 defines the general terms used to describe weaves, including warp, weft, pick, face, back, interlacing, float and design paper, and describes the three basic weaves.

Those three behave differently in your hands. Plain weave alternates over and under on every pick, giving the most interlacing points per area, so it is stable, relatively stiff, and frays at a moderate rate. Poplin, calico and quilting cotton all sit here. Twill floats each yarn over two or more before going under, producing the diagonal line you see in denim and gabardine; fewer interlacing points mean better drape, more diagonal give and a tendency to torque if the fabric is unbalanced. Satin weave has long floats and very few interlacing points, which is what produces the sheen, and also what makes it slippery, prone to snagging and inclined to fray badly.

The key point for pattern matching is that a woven has almost no stretch along either yarn direction. What give it has comes from the bias, at 45 degrees, where the yarn grid can deform into a parallelogram.

Knits: one yarn looping through itself

A knitted fabric is built from loops rather than crossings, and that is why it stretches and recovers. Pull a knit and the loops change shape before any yarn has to extend. Release it and the loops return. A woven has no equivalent mechanism, so once you have pulled it past its bias give, it stays distorted.

ISO 8388 provides the vocabulary for knitted fabric types, which is the reference behind the two broad families. Weft knits are made by feeding yarn across the fabric, loop by loop, and include jersey, rib, interlock and purl. They stretch most across the width, they curl at cut edges in the case of single jersey, and they will run or ladder if a loop breaks. Warp knits are made with many yarns running lengthwise, each forming loops that link sideways, and include tricot and raschel. They are more dimensionally stable, they resist laddering, and they are what most swimwear, lingerie fabric and lining tricot are made from.

Nonwovens: bonded fibre, no yarn at all

Nonwovens skip the yarn stage entirely. ISO 9092, the nonwovens vocabulary standard, establishes the definition of the term and the auxiliary terminology that distinguishes nonwovens from other materials. In practice a nonwoven is a sheet or web of fibres held together by friction, adhesion or cohesion rather than by interlacing or looping.

Sewists meet nonwovens constantly without naming them: most fusible interfacing, craft felt, stabiliser for machine embroidery, disposable pattern tracing material. They have no grain in the woven sense, so they can be cut in any direction, and they do not fray. They also have little recovery, so a nonwoven interfacing stretched during application stays stretched.

Testing stretch before you choose a pattern

Patterns for knits usually specify a required stretch percentage, and guessing is unreliable. Measure it. Fold the fabric a few inches from a cut edge, mark a 10 centimetre section across the greatest stretch direction, and stretch it comfortably against a ruler without forcing. If the 10 centimetre section reaches 15 centimetres before it resists, that is 50 percent stretch. Then let go and check that it returns to 10 centimetres, because recovery is a separate property. A fabric with plenty of stretch and poor recovery will bag at the elbows and seat.

Matching structure to the pattern

• A pattern drafted for wovens has ease built in for a fabric that does not stretch. Made in a knit, it will be too big and shapeless.
• A pattern drafted for knits has negative ease and relies on the fabric stretching to fit. Made in a woven, it will not go on.
• Satin and other long float weaves need sharp needles, fine pins placed inside seam allowances, and a seam finish, because they fray.
• Single jersey needs a stitch with give, since a plain lockstitch across a stretched knit seam will snap.
• Nonwoven interfacing should be matched to the fashion fabric's behaviour, not just its weight, since a rigid nonwoven under a drapey knit fights it.