Imagine approving a checked cotton fabric by shade, weight and construction, only to find that its horizontal checks climb across a shirt front or curve around a kurta pocket. The fabric may be free of holes and stains, yet its geometry is unsuitable for the intended garment. Bow and skew deserve their own inspection decision because they concern the arrangement of yarns, not simply the dimensions of a rectangular piece.
Bow and skew are different distortions
Warp yarns normally run along the fabric length; weft yarns run across it. Bow describes curvature in the yarn path. Skew describes straight weft yarns lying obliquely rather than perpendicular to the warp. Both may occur together. A curved weft line can also change slope within the width, so checking only the two edges may miss local distortion. These distinctions underpin ISO 13015:2013.
Conceptual comparison: bow curves the crosswise yarn path; skew tilts it. The illustrated distortions are exaggerated, not measured specimens.
Measure the yarn path, not an untidy cut edge
Lay the conditioned fabric flat without tension. Identify the actual weft path rather than assuming that a cut edge or printed stripe follows it. A pick glass helps distinguish yarn direction from surface decoration.
For simple overall skew, the principle is longitudinal displacement divided by the useful crosswise width, multiplied by 100. An illustrative 30 mm displacement across 1,500 mm gives 2%. This is a slope percentage, not an angle in degrees. Under ISO 13015, local skew requires assessment of the relevant portions rather than automatically using the full width as every denominator.
Bow concerns deviation from a straight reference joining the yarn’s ends. Record the method, reference length and units: a bow distance in millimetres is not automatically interchangeable with a buyer’s width-based bow percentage. Use the complete agreed standard for contractual testing.
Conceptual inspection scene: following an actual yarn avoids confusing structural distortion with the shape of a cut edge.
Three questions need different tests
A report should distinguish the fabric’s present geometry from changes caused by care and the behaviour of a sewn garment. The following methods address different questions; their percentages should not be substituted for one another.
| Question | Relevant method |
|---|---|
| How much bow or skew is present in the original fabric? | ASTM D3882-08(2025), covering woven filling yarns and knitted courses |
| How does fabric skew change after home laundering? | AATCC TM179-2025 |
| How does a garment seam twist before and after home laundering? | AATCC TM207-2025 |
This separation is particularly important when a mill supplies finished fabric but the garment maker subsequently launders the sewn product. The blog’s explanation of fabric and garment performance testing provides the broader approval context.
Look along the process, not only at the loom
Unequal tension across a fabric web can create distortion during manufacturing and wet processing. Therefore, finding bow in finished cloth does not prove that weaving alone caused it. Compare retained samples or measurements before and after key stages to locate where the geometry changes.
Mahlo’s technical overview identifies uneven tension distribution as a common source of unwanted distortion. For a practical investigation, check fabric entry alignment, the left-to-right tension balance, roller condition and the way the web enters and leaves finishing equipment. These are investigation points, not proof of a particular machine fault. Record the article, width, speed and process stage so that a later improvement can be traced to a controlled change.
Straightening requires feedback and verification
Industrial weft straighteners combine distortion detection with mechanical correction. Mahlo’s Orthopac documentation describes skew and bow rollers used for the respective corrections. Correcting one geometry should not be assumed to correct every irregular or changing distortion.
A sensible mill trial checks the incoming fabric, adjusts within the equipment supplier’s operating guidance, and verifies the output. Retain evidence of residual distortion rather than relying solely on a control-screen setpoint. Where washing is part of the product route, include the relevant after-care assessment. Temporary visual improvement is not enough if the customer’s approved appearance is lost later.
Denim is the important exception
Zero skew is not a universal objective. ASTM D3882 explicitly recognises applications where specified skew helps prevent trouser-leg twisting in twill fabrics. Intentional, controlled skew must therefore be distinguished from uncontrolled distortion. For denim, obtain the supplier’s approved target and assess the intended garment-washing route; do not apply an ordinary checked-shirting rule indiscriminately.
Turn inspection into a cutting decision
For Indian apparel sourcing, consider checked shirting, woven kurta fabrics and blouse materials separately. A small patch pocket, a long placket and a broad front panel expose different alignment problems. As a practical approval exercise, place representative pattern pieces on suspect fabric and make a sample rather than relying only on a small swatch.
Conceptual cutting-room example: pocket and body checks need an agreed matching standard, not merely an acceptable average fabric result.
Agree tolerances by product and method before bulk purchase. ASTM D3882 notes that individual rolls are normally judged using their maximum distortion, rather than a favourable roll average. Keep roll identity and the positions of unacceptable sections. Rework, segregation or rejection should follow the agreed disposition; forcing distorted fabric into a lay is not a reliable correction. Link this decision to cutting-room control and recalculate usable consumption where pattern matching changes the marker plan.
Make supplier feedback reproducible. A useful defect record includes roll identity, useful width, position along the roll, direction of skew, maximum observed distortion, test method and care state. Photograph the yarn trace with a scale and retain labelled samples. If laboratories disagree, first compare specimen selection, preparation and calculation basis. The important question is whether both parties measured the same property on comparable material, not simply which report shows the smaller number.
Source acknowledgement
Sources checked on 17 October 2026: ISO 13015:2013 and its published preview; ASTM D3882-08(2025); AATCC’s method-selection guidance and 2026 Manual announcement, confirming TM179-2025 and TM207-2025; and Mahlo’s distortion-correction documentation. The calculation and sourcing examples are explanatory, not acceptance limits. The three original AI-generated illustrations are conceptual and do not represent laboratory results.
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Goyal, P. Bow and Skew in Woven Fabrics: Measurement, Causes and Cutting-Room Control. My Textile Notes. Available at: http://mytextilenotes.blogspot.com/2026/10/bow-and-skew-in-woven-fabrics.html
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