Fabric defect · Knit fabric - Barre defect in knit 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, barre shows as bands across the width, often at an even spacing.

Cotton Incorporated defines barre as "an unintentional, repetitive visual pattern of continuous bars and stripes usually parallel to the filling of woven fabric or to the courses of circular knit fabric" ¹. In a warp knit it runs along the length instead, following the yarn ¹.

A streak can be one course wide or several, a shadow band. It can come from physical, optical or dye differences in the yarns, from geometric differences in the fabric's structure, or from any combination of these ¹.

Woven fabric has its own filling barre, a cluster of streaks in the filling direction with normal filling between them ². Woven bands are covered on the filling bars page.

Barre repeats; that is part of its definition. Cotton Incorporated has the analyst record how often the bars come and which way they run, whether they are dark or light, and the total length of the pattern repeat ¹. On a single jersey machine, one turn knits a course for each feed of yarn ³, so a fault at one feed comes back once a turn, after as many courses as the machine has feeds.

A streak along the length points elsewhere: Cotton Incorporated links worn needles to streaks in the length direction ¹.

Barre is a continuous defect. One buyer manual, which follows the 4-point system of ASTM D5430, lists it among continuous defects, with uneven finish, and gives up to 4 points to each yard or metre that has one. No linear yard or metre gets more than 4 points, however many defects it holds ⁴. Barre down the length of a roll can cost 4 points in every yard, and a buyer can set a stricter rule.

Cotton Incorporated notes that dyeing to a very dark or very light shade can mask barre ¹.

Cotton Incorporated's bulletin sets out how a lab separates the causes: viewing the fabric flat, on both sides, under fluorescent and ultraviolet light; an instrument that isolates barre caused by physical differences; taking the fabric apart; microscopy; and a tester for knitting tension ¹.

To prevent barre, the bulletin asks for consistency: labelled stock yarn, fugitive tints to tell yarn lots apart, first-in, first-out use of yarn, well-kept machines, and sample dyeings before full production ¹.