Standardized Testing
An international testing protocol defines the method for determining the crimp of warp and weft yarns in woven textile fabrics. Performing an ISO 7211 crimp analysis allows mills to calculate the percentage of yarn contraction that occurs due to the weaving process. This standard requires the extraction of yarns from a conditioned fabric sample and the measurement of their straight lengths under a specified tension.
Laboratory technicians document these measurements in the fabric’s structural analysis report.
Yield Calculation
The test measures the difference between the length of the straight yarn and the length of the fabric from which it was removed. For linen fabrics, conducting an ISO 7211 crimp analysis is essential to calculate the correct yarn consumption and the fabric’s raw material cost. Because flax yarns have low elasticity, the crimp percentage must be tightly controlled on the loom to prevent fabric stiffness or excess shrinkage.
The results of the analysis are utilized by production managers to adjust the tension settings on the weaving machines for future batches, ensuring that the finished linen fabric matches the thickness and weight specified in the buyer’s contract.
Fabric Specification
This crimp value is a key parameter in the fabric design sheet and is checked during final quality inspections. It helps the mill ensure that the fabric has been woven with the correct yarn spacing. The verified crimp data is sent to the purchaser with each shipping invoice.
