Yarn Elasticity
Undyed yarn exhibits a specific degree of waviness and contraction resulting from the spinning and texturizing processes. Variations in this physical property, known as greige yarn crimp variance, measure the difference in texture and stretchability across different batches of raw yarn. This inconsistency stems from uneven heat setting or tension during the drawing stage.
The test must occur before the yarn is loaded onto the knitting machine, as subsequent processing cannot correct these molecular differences.
Weaving Effect
Uneven stretch in the raw material leads to visible fabric defects such as barré lines and striping after the dyeing stage. When yarn with highly variable crimp is woven into a fabric, the tension variations cause different rates of dye absorption. This results in alternating light and dark bands across the fabric width.
Controlling this variation is critical for producing solid-coloured garments.
Measurement Method
Testing involves measuring the length of the yarn under a light preload and then under a heavy tension that removes the crimp. The difference between these two lengths is calculated as a percentage of the original crimped length. This procedure is repeated for multiple packages in the shipment.
Quality Standard
Acceptable limits for this variation are defined in the supply contract to ensure consistent fabric appearance. If the crimp variance exceeds two percent, the yarn is rejected or redirected to patterned fabrics where the texture changes are less noticeable. This rigorous quality standard protects the garment manufacturer from costly fabric failures.
