Fabric defect · Yarn - Foreign fibers and contamination in fabric

Foreign fibers are fibers that do not belong in a yarn or fabric: another fiber, another color, or bits of plastic, leaf or other matter that came in with the raw fiber or settled on the yarn in the mill. Many are hard to see in the greige and show only after dyeing, as specks or short streaks of another shade.

A few short stray fibers in the face of the fabric, outlined in cyan.

What ConductVision Textile records

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 foreign fiber is a spot.

Fabric inspectionDefects, points and a final points forecast

What foreign fibers are

A U.S. military glossary of knitting imperfections defines foreign matter as "waste, fly or extraneous material that has been knit into the fabric or spun into the yarn" ¹. A U.S. federal glossary uses nearly the same words for woven cloth, under the names woven-in waste, gout and loom fly: "waste that has been woven into the cloth, or spun into the yarn" ².

Goldberg's 1950 casebook defines fly as "short fibers which generally float in the air in a spinning or weaving mill and which may come to rest and be deposited on yarns or fabric during the process of manufacture" ³. Where a weave room runs more than one fiber, fly of one kind trapped in goods of another is nearly impossible to find until the goods are dyed. Then, because the fibers take dye differently, they show "in different shades or completely undyed" ³.

Contamination that is not fiber behaves the same way. Goldberg notes that bits of leaf and seed can survive every cleaning process and "emerge as tiny dark specks in an otherwise perfect piece of fine woven goods" ³. With plastic, the International Textile Manufacturers Federation notes, the damage "is becoming visible only by the time the fabric leaves the final finishing process" ⁴.

Where foreign fibers come from

Goldberg wrote that "every single operation is a possible source of defect through contamination" ³. These are the routes his cases and later studies trace, from the field to the loom.

Where foreign fibers come from
Stage	What happens	What to check
Field and gin	Plastic twine or rope that reaches the gin is shredded and spread through the lint; even a short piece "can contaminate several bales of cotton" ⁵.	Bale origins, and contamination by growth
Field and gin	Hats, gloves and cleaning rags near gins and seed cotton can add apparel fibers ⁵.	What suppliers do at the gin
Raw cotton	Bales can carry leaves and feathers; strings and fabric of plastic film, woven plastic, jute or cotton; sand, dust, rust and metal; or grease, oil, rubber, stamp color and tar. These are the kinds an international survey asks spinning mills to rate ⁴.	Contamination by growth and origin
Raw cotton	Asphalt paint on bale straps, where too thick to dry, stuck to the cotton; the tar left black spots in the cloth and kept the yarn from drafting properly, which left slubs ³.	Bale straps and covers
Blending	Dark wool hairs spun in with the yarn showed as short dark streaks; in goods finished white or light, nothing in finishing removes or bleaches them ³.	Wool selected free of black hairs for white and light shades
Carding	Cards probably not cleaned of cotton before a run of rayon left bunches of cotton fly in the yarn, which dyed lighter as short slubs ³.	Cleaning between fibers on shared preparatory machines
Weaving	Fly from other fibers in the weave room is trapped in the goods. In one case, red cotton fibers from plush facing on the loom race plates were woven in and showed as small red streaks in white goods ³.	Fly in mixed weave rooms, and loom coverings

Where foreign fibers show on a roll

Goldberg's cases show how foreign fibers sit on a roll: leaf and seed as tiny dark specks, red cotton fibers from a loom as small red streaks running fillingwise through the piece, cotton fly in rayon as short light slubs in both warp and filling, and dark wool hairs as short dark streaks ³.

The shade of the finished goods decides whether they show. In the red streak case, "in cases in which the goods were finished in medium and dark shades, the contaminating fibers were not visible" ³. Plastic may not show until the fabric leaves final finishing ⁴.

Defect positionWhat a defect's place on the roll points to

How foreign fibers count

Cotton Incorporated's grading guide lists color fly among isolated defects and counts every defect visible at normal inspection speed from one yard or one metre. It also lets the purchaser and the supplier agree which small characteristics are not counted ⁶. A foreign fiber that is counted is scored by its length on the 4-point scale, so a speck or a streak up to 3 inches gets 1 point ⁷.

For military contract cloth, a 2012 U.S. specification scores "any embedded foreign matter or uncleanness" at 4 points for each yard in which it occurs, when it is clearly visible at 3 feet by direct view or with light through the fabric ⁸. A 2019 military standard scores the same defect in cloth, webbings, knits and threads ⁹.

What research says

The International Textile Manufacturers Federation asks spinning mills to rate the cotton growths they used. In its 2019 survey of 128 mills in 25 countries, mills rated 26 percent of cottons moderately or seriously contaminated. Organic matter such as leaves, feathers, paper and leather topped the list at 55 percent, and strings and fabrics of plastic film each affected 39 percent ⁴.

Its 2022 survey, of 104 mills in 21 countries, rated 22 percent of cottons moderately or seriously contaminated. Organic matter came first again, at 43 percent, and fabrics made of plastic film affected 39 percent ¹⁰.

A 2017 paper by USDA researchers explains how plastic reaches the fabric. Machines break it into single fibers or small pieces that pass through normal mill processing unnoticed, until a yarn breaks in spinning or the fabric reaches inspection. The pieces raise spinning costs, and "large quantities of fabric must be sold as defective materials or seconds" ⁵.

Sources

Pilot - How a pilot starts

We start with recorded video of your inspection frame and agree with your team on one fabric to test. The pilot runs for a set time, and before it starts we agree on what counts as success. For each defect it marks, ConductVision saves a still image and its place on the roll on your network for your inspector to check.

You bring: Recorded video of fabric running over your inspection frame
We set up: One fabric, and the limit you grade it against
You get: Marked defects, running points and a final points forecast for each roll, and a results report checked against what we agreed

One question to start with

Which yarn or fabric shows foreign fibers most often?

Plan a pilot