Fabric defect · Dyeing and printing - Dye spots and chemical stains: causes and how they count

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 dye spot is a spot.

A U.S. federal glossary of fabric imperfections defines a dye stain as "an area of discoloration in the cloth" and a dye streak as "a dye stain extended as an irregular stripe in the cloth" ¹. A U.S. military glossary of knitting imperfections adds "an area of shade difference" to its dye stain, and defines a speck as "a small particle of foreign substance" ².

Goldberg's casebook describes how dye stains arise: "through the deposition of some undissolved color, or by contamination from particles of dry dyestuff floating in the air of the dyehouse." Many chemicals "produce permanent stains or resist spots" when they are spattered by accident in the dyehouse or the finishing plant ³.

White and light-shade goods are especially at risk. They readily pick up "tiny color specks" from any dyehouse equipment that is not kept thoroughly clean ³.

In Goldberg's cases, small dark spots from undissolved dye lay "scattered throughout the piece." White stains, where some chemical had partly dissolved the acetate yarns, were "irregular in size and shape" and scattered too ³.

A stain can tell you when it happened. Discolored areas and holes along one selvedge of a dyed rayon shirting tested strongly acid, and Goldberg placed the damage after dyeing: "If the damage had taken place in the gray goods, there would have been little or no acid remaining in the fabric after it had been wet-processed" ³.

Cotton Incorporated's defect glossary rates its color spot example a major defect ⁵. Its grading guide defines a major defect as one severe enough, if exposed, to make the end item a second, and counts every defect visible at normal inspection speed from one yard or one metre ⁶.

On the 4-point scale a spot scores 1 point up to 3 inches, 2 points over 3 up to 6 inches, 3 points over 6 up to 9 inches and 4 points over 9 inches ⁷.

In a white broadcloth shirting with small blue specks and short blue streaks, the microscope showed color stains, not deposits on the surface. Under ultraviolet light the specks glowed bright orange, and "scores of additional smaller specks became visible." Goldberg traced them to a bluing pigment poorly dispersed in finishing, and found no sign of it in the greige goods as delivered to the finisher ³.

In an acetate taffeta, microscopic and chemical analysis showed small dark spots to be particles of undissolved dye, deposited on the cloth during or after dyeing ³.

Not every stain gives up its cause. Goldberg warns that finding the chemical behind a spattered stain "is generally extremely difficult" ³.