Fabric defect · Holes, threads and stains - Snags and pulled threads in fabric
A snag is a yarn pulled out of place, usually by a sharp point or a rough surface. It leaves a loop or a pulled end standing out from the face of the fabric.
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 snag is a spot.
What a snag is
A U.S. military glossary of knitting imperfections defines a snag as "a yarn or yarns pulled out of place, usually by a sharp point or projection" 1. A 2020 study of knit fabric quotes the snag entry in ASTM D3990, the standard terms for fabric defects 2.
Snags happen mostly in fabric made from continuous filament yarn. A university module on knit defects says snagging occurs "almost without exception" in such fabric, where filaments or yarns are pulled out by rough surfaces 3.
What causes snags
| Stage | What happens | What to check |
|---|---|---|
| Knitting | Rough surfaces on yarn guides, yarn feeders, needles and the fabric take-down catch the yarn 3. | Guides, feeders, needles and take-down |
| Dyeing and drying | Rough contact points on soft-flow dyeing machines, tumble dryers and centrifuges 3. | Every point where the fabric touches these machines |
| Handling | A sharp point or projection anywhere along the way can pull a yarn out of place 1. | Sharp edges and burrs on carts, racks and tables |
| Yarn | To make yarn snag less, the same module advises a coarser single filament, less crimp elasticity and more twist 3. | How fine each filament is, the crimp and the twist |
Where snags show on a roll
A snag is a single spot and can sit anywhere along the roll. Snags that repeat at a regular spacing point to a part the fabric runs over, as Goldberg found for repeating damage in woven goods 4.
How snags count
Under the 4-point system, a snag is scored by its length, as most defects are 5. Agree with your buyer whether that is the length of the loop or of the pulled line it leaves. A buyer's manual can also set its own rule for snags and pulls.
Sources
- 1U.S. Department of Defense, MIL-STD-1491, Glossary of Knitting Imperfections (1971)
- 2A. K. M. M. Hossain and M. I. Islam, Exploring weft knit fabric defects based on their presence and quality impact: a case study, Communications in Development and Assembling of Textile Products 1(1), 57-64 (2020)
- 3S. Natarajan, Knitted fabric defects, chapter 17 of Textile Manufacturing and Testing, e-PG Pathshala, INFLIBNET
- 4J. B. Goldberg, Fabric Defects: Case Histories of Imperfections in Woven Cotton and Rayon Fabrics, McGraw-Hill (1950)
- 5DXLG Fabric Inspection Guidelines, version 1.1
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 fabric snags most often?
Related pages
- Loose threadsA yarn end or loop lying on the face of the fabric.
- HolesAn opening where yarns have broken or been cut.
- Runs and laddersStitches that unravel down a wale.
- Defect positionWhat a defect's place on the roll points to
- Fabric defect libraryWoven, knit and yarn defects, and how they are measured