Loom Stoppage Defect
Horizontal bands of varying density appear in a fabric when a weaving machine is restarted after a pause. The phenomenon of restart pick barre occurs because the tension on the warp and the position of the cloth fell change while the loom is stationary. When the machine resumes, the first few weft insertions are not spaced identically to those produced during continuous operation.
Mechanical Tension Shift
During a stop, the warp yarns undergo stress relaxation, causing them to stretch or slacken slightly over time. This change in the physical state of the yarn leads to restart pick barre as the beat-up force of the reed varies on the initial picks. In linen weaving, the high tension required for flax makes the material particularly sensitive to these interruptions.
Automated loom controllers attempt to compensate by moving the cloth fell slightly before the first pick is inserted.
Visual Quality Impact
These bands are often visible as shadows or streaks across the width of the linen cloth, especially in light-colored or plain-weave fabrics. Minimizing restart pick barre requires quick intervention by the weaver to fix broken ends and a well-calibrated electronic let-off system. Modern looms include anti-crack settings that adjust the motor timing to ensure the first pick lands in the correct position.
Avoiding frequent stops is the best strategy for maintaining a flawless fabric surface.
