Fabric skew, bow and spirality: what to check before you cut

On this page

Three distortions, three different shapes
Why buyers should care
How it is measured
Where it comes from
Acceptance limits — there is no universal number
How we handle it (woven range)

Three distortions, three different shapes

All three are grain distortion — the weft yarns (in wovens) or courses (in knits) are not running at a clean 90° to the selvedge. They look different:

Skew — the weft line is straight but runs at an angle across the width, so one selvedge is ahead of the other. A checked cloth becomes a stack of parallelograms instead of squares.
Bow — the weft line curves, like a smile or a frown across the width; the centre lags behind or runs ahead of the edges.
Spirality (mainly knitted) — the wales slant away from vertical. In a finished T-shirt the side seam swings toward the front or back after the first wash.

Buyers usually meet them together, but the fix for each is different, so the names matter.

Why buyers should care

Stripes and checks stop matching. A woven stripe or yarn-dyed check looks slanted across a garment body.
Seams twist after washing. Side seams swing front or back, trouser legs turn, hems stop hanging level.
It often hides until the first home wash. Finishing can hold the cloth square temporarily; relaxation releases the distortion.

How it is measured

Lay the fabric flat without tension. Measure how far a weft yarn, course or stripe has moved from a line drawn perpendicular to the selvedge, divide by the fabric width, and multiply by 100:

Measure	Formula
Skew %	displacement along selvedge ÷ fabric width × 100
Bow %	max arc depth ÷ fabric width × 100

Commonly referenced test methods:

Standard	What it measures
ASTM D3882	Bow and skew in woven and knitted fabrics (confirm current edition)
AATCC TM179	Skew change after home laundering (confirm current edition)
AATCC TM207	Seam twist in finished garments
ISO 16322-1 / 2 / 3	Wale spirality / spirality after laundering in woven and knitted fabrics

Where it comes from

Woven skew & bow: one side of the cloth fed ahead of the other on the stenter, or the weft straightener not set or working. Twill fabrics (denim, chino) tend to skew in the twill direction after washing — some mills finish them with a deliberate pre-skew to counteract this, in which case the agreed value becomes part of the spec.
Knit spirality: torque in the yarn (high-twist single yarns try to untwist), multi-feeder circular knitting, and finishing that only hides the twist for a while.
Cutting: aligning panels to the fabric edge instead of the true grain transfers the distortion straight into the garment.

Acceptance limits — there is no universal number

Several reference points float around the industry, but none is a law:

Often-cited reference	Value
Premium UK woven spec	≤ 2% skew, ≤ 1.5% bow
Stretch knits / printed stripes	> 3% skew often treated as critical
Single-jersey spirality (starting point)	up to ~5% sometimes used

The honest rule: no single limit fits every product. A solid cloth, an engineered stripe, tubular underwear and a side-seamed T-shirt each have different visual and sewing tolerance. The buyer must define both the test method and the acceptance tolerance in the tech pack before bulk — your brand standard takes precedence over any number quoted here.

How we handle it (woven range)

We are an integrated woven mill (yarn dyeing → weaving → fabric dyeing → printing → finishing), so grain control happens on our own finishing range, where weft straighteners keep the weft square and final inspection records skew and bow alongside the 4-point result. For twill constructions, a controlled pre-skew can be written into the agreed specification. Specific achievable limits depend on the construction and end use and are confirmed in writing at enquiry. We recommend stating your method and tolerance in the quote request so we test to it; see how to read a fabric specification for the other fields.