Woven and Knitted Fabric Structural Construction Specifications
Fabric specifications mandate exact finished thread densities, stitch lengths, and test conditions to enforce supplier compliance and control landed costs.
Spirality Skew
Distortion Type
Fabric structural distortions occur when the courses and wales of a knitted material do not meet at a ninety degree angle. A spirality skew results from the residual torque in the yarn which causes the loops to tilt in one direction. This phenomenon is most common in single jersey fabrics made from highly twisted yarns.
Measurement Process
Laboratory technicians quantify the distortion by marking a square on the fabric and measuring the deviation of the side seams after washing. The spirality skew is expressed as a percentage of the total width. If the angle exceeds five percent, the garment will likely twist on the body of the wearer.
Mechanical Correction
Finishing plants use stenter frames and skew straightening machines to pull the fabric back into alignment before the final heat setting. While this treatment masks the spirality skew temporarily, the internal stresses in the yarn often cause the twist to return during home laundering.
Production Impact
Cutting and sewing operations are disrupted when the fabric grain is not straight. If a cutter ignores the spirality skew, the side seams of the finished shirt will migrate toward the front and back. This misalignment creates a poor fit and makes it impossible to align stripes or patterns correctly across the garment.
Quality control teams at the sewing factory must check every roll of fabric to ensure that the grain line is within the allowable tolerance before they start the production run.