Usable Width, Bow and Skew: How Width and Grain Control Marker Efficiency in Woven Polyester and Nylon
A woven polyester or nylon fabric is sold by the metre, bought by the width and consumed by the marker. Those three numbers are not the same, and the gap between them is where garment programs quietly lose cloth. A roll quoted at a generous width can arrive with two centimetres of pin holes down each edge and a weft line that curves three centimetres across the panel; neither looks like a defect until the marker is laid. This guide covers the four width numbers, how bow and skew are measured, what distortion costs in cutting, and how to write width and grain so the result repeats.
Why Width Is Never One Number
Every woven has at least four widths, and only one belongs on the order sheet. Grey, or loomstate, width comes off the loom. Finished width leaves the stenter after dyeing and setting. Full width is the edge-to-edge measurement of the finished roll, including everything the cutting room cannot use. Usable width is what remains once selvedge, pin holes, edge damage and distortion allowance come off.
Confusion between the last two is the most common specification error in synthetic woven programs. A mill quoting full width is quoting the standard measurement for that cloth; the buyer cuts on the usable width. When the two are not distinguished in writing, the difference surfaces at the cutting table, where it is expensive. There is also a fifth number that matters more than any of them: the minimum usable width on any single piece. An average is not a specification, and one narrow roll is enough to stop a cutting line.
The Four Width Numbers Side by Side
Each number answers a different question, and only one belongs in a purchase contract.
| Measurement | What it includes | Specify it? |
|---|---|---|
| Grey width | Width before any wet processing | No — an input, not a delivery property |
| Finished width | Width after dyeing, setting and finishing | Only as a reference beside usable width |
| Full width | Edge to edge, including selvedge and pin holes | No — it overstates what can be cut |
| Usable width | Full width minus selvedge, holes, damage, distortion | Yes — with a stated minimum per piece |
Bow and Skew Are Two Different Faults
Both describe weft yarns no longer square to the warp, and both are measured the same way, but they cut differently. Bow is a curve: the weft line arcs across the fabric, symmetric about the centre. Skew is a diagonal: the weft runs at a constant angle from selvedge to selvedge, so one edge leads the other along the length.
Bow wastes cloth in the middle of the panel, because the marker must sit inside the arc. Skew wastes cloth along the length, and produces garments that twist after washing as the yarns relax back toward square. Both are measured as a percentage of width, not in centimetres: three centimetres on a narrow cloth is far worse than three on a wide one. Measure on relaxed, flat fabric, because tension hides distortion that reappears on the cutting table.
Where Distortion Comes From
Nearly all bow and skew is introduced after weaving. The loom makes weft square; the stenter is where it stops being square. Uneven tension across the width while the cloth is hot pulls the weft out of line permanently, because heat setting locks in whatever geometry the fabric holds at that moment.
Three mechanisms account for most of it: uneven pinning or clipping lets one edge run ahead; a temperature or dwell difference across the chamber sets the two sides differently; and off-centre batching distorts cloth that left the frame straight. Mechanical straighteners can correct skew but are less effective on bow, which is why bow is prevented rather than fixed. Finishing adds tension cycles too — the hand routes in our guide to choosing a hand-feel finish, and the thermal history set during dyeing, reduction clearing and heat setting, which is what makes the distortion permanent.
What It Costs in the Cutting Room
Marker efficiency — the share of fabric area that ends up in garment pieces — converts width and grain into money. On woven synthetics it commonly lands in the eighties to low nineties percent depending on the style and how pieces nest. It is not a property of the fabric alone; it is fabric, marker and tolerance working together.
Width sets the ceiling. If a style needs a panel width the usable width cannot provide, no marker recovers it. A one-centimetre shortfall on a tight marker can drop efficiency by several points, and that loss applies to every garment in the order. Distortion sets the floor: skew forces waste triangles along both edges, bow forces a wider allowance through the centre. Cutting to the fabric edge instead of the grain produces panels that twist in wear, which is the more expensive version because the customer finds it.
The Yield Arithmetic Worth Doing First
Three checks catch most width problems while they are still cheap to fix.
- Take usable width, not full width. Subtract both selvedges and any pin-hole band before testing the marker: a cloth quoted at 150 centimetres with 1.5 unusable each side gives 147 to cut on.
- Subtract the distortion allowance. Two percent skew on a 150-centimetre cloth consumes roughly three centimetres along the length.
- Test the narrowest roll, not the average. If the marker only fits the average, it will fail on the worst roll in the shipment.
Weight interacts here, because what you buy is area. Our article on specifying fabric weight and matching it to end use covers the grams per square metre side; width is the other half of the same cost equation. A slightly heavier cloth on a wider usable width can cost less per garment than a lighter one that cuts badly.
Setting a Tolerance That Fits the Garment
Grain and width tolerance should be set from the marker, not copied from a previous order. A plain, small-panel style tolerates more distortion than a long, matched-panel style, and a check or stripe tolerates none, because the pattern makes any deviation visible. Long panels, matched panels and large prints demand tighter control; short, plain, unmatched panels accept more.
Two clauses make the limit enforceable: state that measurement is taken on relaxed fabric laid flat without tension, and state the sampling basis — per roll, per piece, or across a lot. Without both, the same cloth can pass one inspection and fail the next. The acceptance structure in our article on grading woven defects with the four-point system applies the same logic to surface faults.
Why Polyester and Nylon Differ
Both polymers are heat-set and hold the geometry they are given, but they arrive differently. Polyester is dimensionally stable once set and resists further movement in washing. Nylon is more prone to relaxation movement afterwards, so a nylon program needs that behaviour tested on the finished cloth rather than assumed from the base. Our comparison of polyester versus nylon wovens covers the wider trade-offs, and the construction variables in our guide to nylon ripstop specification affect how the cloth behaves on the stenter: a denser, higher-cover construction resists distortion better than an open one.
Writing Width and Grain Into the Specification
Six lines turn a width requirement into something enforceable.
- Specify usable width, not full width, and label it as such.
- State a minimum per piece or per roll, not an average across the delivery.
- Give the width tolerance as a plus-or-minus range, and say whether plus is acceptable.
- State bow and skew as a maximum percentage of width, measured on relaxed fabric.
- Name the measurement condition: flat, relaxed, and the sampling basis per lot.
- Declare the consequence — rejection, credit, or acceptance at an agreed allowance.
Anything not written will be measured the mill's way, which is normally full width under light tension. The wider build-up of a synthetic woven order is set out in our polyester woven buyer's guide. Usable widths, tolerance bands and grain limits depend on the construction and the order, and are confirmed on request.
Frequently Asked Questions
What is the difference between bow and skew?
Bow is a curve across the width, symmetric about the centre. Skew is a constant diagonal, with one selvedge leading the other along the length. Both are measured as a percentage of fabric width, but they waste cloth in different places and need different remedies.
Why is usable width smaller than the quoted width?
Because the quoted figure is normally the full edge-to-edge width, which includes selvedge, pin holes from the stenter chain and any edge damage. Usable width removes those and a further allowance for bow or skew. Always test the marker against the usable figure.
Can bow and skew be corrected after the fabric is made?
Skew can often be straightened mechanically, because it is a uniform diagonal. Bow is harder, since the curve is set into the middle of the panel. In practice both are prevented at the stenter rather than corrected afterwards.
How much distortion is acceptable?
It depends entirely on the garment. Long or matched panels, stripes and large prints need tight control; short plain panels tolerate more. Set the limit from the marker and style, and state it as a maximum percentage of width on relaxed fabric.
Next Step
Decide the usable width your marker needs first, then write the tolerance and grain limit around it. Send the panel width, the style and the pattern type and we will come back with the usable width we can hold, the bow and skew limit for that construction, and how to state it on the order sheet. If you already have a specification, send the width and grain clause and we will confirm whether it is measurable as written.
