The resistance of the yarns forming a woven fabric to slip or unwinding is called shear or opening resistance. This depends on the twist of the yarns, the kind of fibers that make up the yarn, the weaving density of the fabric and the connections of the weft and warp yarns. In fabrics with high stitch opening strength, yarns do not deteriorate during sewing and use.

In woven fabrics, the resistance to suturing is the strength value that must be applied perpendicular to the stitch for a certain amount of displacement of yarns parallel to the stitch. These tests are applied to woven fabrics. These tests are not applied to belts and other industrial textile products.

For physical tests performed by authorized laboratories, many standards issued by local and foreign organizations are complied with. In this context, the following standards are used in stitching tests:

• TS EN ISO 13936-1 Textile - Determination of shear strength of yarns in woven textile products - Sewing method - Part 1
• TS EN ISO 13936-2 Textile - Determination of shear strength of yarns in woven textile products - Sewing method - Part 2
• TS EN ISO 13936-3 Textile - Determination of the shear strength of yarns in woven textile products - Part 3: Needle fastening method
• TS EN ISO 13935-1 Textile - Stitching properties of fabrics and finished textile articles - Part 1: Determination of the maximum force for seam break using the ribbon method
• TS EN ISO 13935-2 Textile - Stitching properties of fabrics and ready-made textile articles - Part 2: Determination of the maximum force for seam breaking using the clutch method

Laboratories to perform sewing opening tests must be accredited from national or international foreign institutions in accordance with the standards of TS EN ISO / IEC 17025 General Conditions for the Competence of Testing and Calibration Laboratories.