Fabric defect · Woven fabric - Reed marks in woven fabric

ConductVision Textile is designed to flag each defect with its place on the roll, its size, its points and a still image. Your inspector names the defect and confirms or dismisses it.

On the defect map in the roll report, a reed mark is a line along the length of the roll.

The reed is a comb of evenly spaced flat metal wires, and the warp ends pass through the spaces between the wires, called dents ¹. A U.S. federal glossary defines a reed mark in cotton and synthetic fabric as "a mark running warpwise in the cloth," and in wool and worsted cloth as "thick or thin lines or both running warpwise in the cloth" ². Goldberg names the usual cause: warp ends spaced unevenly by a damaged reed ¹.

Mills also speak of reediness, or a reedy fabric, which spreads across the cloth instead of showing as one streak. Cotton Incorporated describes a reedy fabric as having "open streaks following the pattern of the reed wires," also called "poor cover" ³, and a teaching module on woven defects describes spacing between groups of warp ends across the width of the fabric ⁴. A 1982 Leeds thesis treats reediness as a matter of local thread spacing, which loom settings change ⁵.

A reed mark can look dark or dull. In one of Goldberg's cases a dark streak came from a cracky open place in the warp left by a damaged reed, and in another a single dull streak came from three neighbouring warp ends chafed in weaving ¹. Cotton Incorporated shows an open reed, where a bent reed wire holds the warp ends apart and the filling shows through ³.

A reed mark runs warpwise, along the length of the cloth ². Goldberg describes warp streaks from damaged reeds running through full pieces, a narrow streak throughout a piece, and several narrow dark streaks running the full length of a piece ¹. Cotton Incorporated puts its reed faults in its first category, narrow or fine-lined warpwise defects "of a continuous or lengthy nature" ^{3, 6}.

In one of Goldberg's cases, warp streaks in a regular pattern across the full width were traced to poor reeding, with double ends split in the reed ¹. Cotton Incorporated describes reedy streaks as following the pattern of the reed wires ³.

Dyeing can bring uneven spacing out. In an acetate fabric, uneven spacing of the warp let the dye penetrate unevenly and left narrow dark streaks, which Goldberg put down to a damaged reed, weak dents or some other shift in the even spacing of the yarns ¹.

A reed mark that runs along the roll is a running defect. One buyer manual, which follows the 4-point system of ASTM D5430, gives a maximum of 4 points to each linear yard or metre that a running defect longer than 9 inches covers, and no linear yard gets more than 4 points ⁷. A reed mark through a whole piece can cost 4 points in every yard.

A faint reed mark counts the same as a strong one once it can be seen: every defect visible at normal inspection speed from one yard or one metre is counted ⁶, and the 4-point system scores it by its length. Cotton Incorporated rates its open reed and reedy examples as major and its reed misdraw as minor ³.

A 1982 Leeds thesis wove fabric while varying the warp tension and the balance and timing of the shed. The settings changed reediness and the air permeability that goes with it, and changed the fabric's other properties fairly little ⁵.

The thesis used air permeability as a gauge of reediness. Permeability fell when the shed was unbalanced, as expected, and fabric samples woven with near balanced and very unbalanced shed tensions showed the difference in reediness clearly ⁵.