Deformation Threshold
Physical boundary beyond which a fiber or yarn cannot return to its original length after the removal of a stretching force marks the end of its elastic behavior. Exceeding the tensile elasticity limit in linen production leads to permanent thinning and eventual rupture of the thread. This occurs because the molecular bonds within the flax cellulose are forced past their point of recovery.
Mechanical Consequence
Loom settings that pull the yarn too close to this threshold cause the fabric to sag once it is removed from the machine. If the warp is stretched permanently during the shedding cycle, the resulting cloth will have poor dimensional stability and will shrink unevenly during washing. This failure is often identified when the fabric weight per square metre falls below the target specification despite the correct thread count.
In extreme cases, the yarn loses its structural integrity and the loom must be stopped to repair multiple breaks across the width of the beam.
Testing Boundary
Determining this threshold involves applying increasing loads to a sample until the stress-strain curve shows a permanent departure from linearity. Once this point is passed, the yarn is no longer suitable for weaving high-quality linen. The measurement is valid only for the specific batch of yarn tested and must be re-evaluated whenever the spinning source changes.
