Testing & Quality Control
Needle penetration damages yarn. Every seam trades fabric strength for construction.
— %
Seam strength as a share of fabric strength
—% retained —% lost
Raising stitch density improves seam strength up to a point, then weakens the fabric through needle damage. Test rather than assume more stitches are better.
Seam Strength & Efficiency Calculator — free, with the formula and a worked example, at Textile School.