Crystalline Cellulose Microfibrillar Realignment and Viscoelastic Shear Dynamics
Microfibrillar realignment under shear dictates linen dimensional stability, demanding controlled loom tension and zero-tension wet relaxation to prevent skewing.
Fell Jump
Displacement Anomaly
Beat-up boundary instability during loom stops creates abrupt local pick density deviations across the cloth construction. The defect known as fell jump occurs when the newly formed cloth edge shifts forward or backward from the reed impact line during an unexpected stop or restart of the weaving machine. High flax yarn stiffness exacerbates this sudden shift because linen lacks the elastic recovery seen in wool or synthetic fibres.
The resulting mismatch appears in finished linen cloth as a distinct horizontal line of high or low pick density.
Loom Dynamics
Loom restart cycles require synchronized take-up motion and warp tension compensation to maintain consistent beat-up geometry. When dynamic braking arrests the machine, warp relaxation pulls the fell line backward against the reed position. Slower motor acceleration during restart prevents the first inserted pick from packing with standard force, leaving a thin bar across the flax fabric width.
Modern electronic take-up motors counter this displacement by executing pre-programmed step offsets upon machine restart. Mill mechanics adjust dynamic braking parameters according to yarn count and reed density settings.
Finishing Appearance
Inspection tables reveal dense restart lines under transmitted perch lighting during standard cloth examination. Finishing processes such as scouring, mercerization, and calender pressing fail to obscure the optical contrast generated by compressed or loose flax picks. Export quality control logs record fell jump occurrences under start-mark defect codes, rejecting rolls that display visible bands within prime garment panels.