Managing off Loom Crimp Contraction in Sized Flax Warps
Managing off-loom flax warp crimp contraction requires precise reed denting allowances, ELO tension tuning, and size solubility control to hit target grey widths.
Yarn Modulus
Tensile Property
Mechanical properties define the resistance of a textile strand to deformation and stretching under an applied load. A high yarn modulus is characteristic of linen, because flax fibers are naturally stiff with very low elongation at break. This physical parameter dictates how the yarn behaves under the tension of spinning and weaving machinery.
Measurement Procedure
Measurement procedures use a tensile tester to plot the force applied against the elongation of the yarn until it breaks. To determine the yarn modulus, the slope of the initial linear portion of the stress-strain curve is calculated. This test must be performed under standard climate conditions of sixty-five percent relative humidity and twenty degrees Celsius to ensure accurate and repeatable results.
Processing Significance
Processing significance lies in the adjustment of tension controls on the warping frames and looms to accommodate the yarn’s stiffness. Because of the high yarn modulus of linen, even slight misalignments in the warp can cause yarn snap-breaks rather than gentle stretching. Mills use these testing values to configure their machinery for different yarn batches, ensuring that the yarn is not subjected to tensions that exceed its elastic limit.
These parameters are recorded in the mill’s yarn specification sheets to guide the weaving department.