Overview
ISO 13015:2013 - "Woven fabrics - Distortion - Determination of skew and bow" defines a standardized laboratory method to measure distortion in woven fabrics where the weft yarns are intended to be perpendicular to the warp yarns. The standard provides clear procedures to quantify overall skew, local skew, weft bow, and warp bow, enabling repeatable fabric distortion measurement for quality control, specification and acceptance testing.
Key topics and requirements
- Scope: Measurement of distortion (skew and bow) in woven fabrics with perpendicular weft and warp yarns.
- Conditioning: Specimens must be conditioned at least 16 hours in the standard atmosphere per ISO 139 before testing.
- Test specimens: Full-width specimens, minimum 500 mm length; do not take specimens from within 1 m of fabric ends.
- Apparatus: Set square (right angle), metallic ruler at least 100 cm (or not less than fabric width) and a 20 cm ruler; measurements to the nearest millimetre.
- Preparation: Two accepted methods to reveal the weft line - marking the selected weft yarn or fraying the specimen to expose it.
- Measurement principle:
- Model the course of a selected weft yarn with one or more triangles.
- For each triangle measure height (a) in the warp direction and base (b) perpendicular to the warp.
- Calculate skew as: Skew% = (a / b) × 100.
- For each specimen measure three weft yarns and record the highest skew value as the result.
- Bow (Annex A):
- Weft bow: greatest perpendicular distance (d in mm) between the exposed weft and a straight line joining its ends.
- Warp bow: greatest perpendicular distance between the fabric edge and a straight line joining two selected edge points.
- Test report requirements: include reference to ISO 13015, fabric identification, preparation method (marking or fraying), positions measured, overall and/or local skew results, weft/warp bow (if measured), and any deviations.
Practical applications
- Quality control in textile mills and finishing plants to ensure panels and yardage meet geometric tolerances.
- Apparel and home-textile manufacturers checking pattern alignment (plaids, stripes, checks) to prevent visual distortion in cut parts.
- Specification and acceptance testing in commercial contracts and technical textile applications where dimensional stability matters.
- Troubleshooting weaving or finishing processes that introduce skew or bow.
Who should use this standard
- Textile and fabric manufacturers, QC laboratories, product designers, apparel manufacturers, commodity graders, and standards/inspection bodies involved in fabric specification and testing.
Related standards
- ISO 139 - Textiles - Standard atmospheres for conditioning and testing (referenced for conditioning and testing atmosphere).
Keywords: ISO 13015, woven fabrics, fabric distortion, skew measurement, bow measurement, weft bow, warp bow, textile testing, fabric quality control.