How T-shirts and knit tops are made
The fabric is knitted on circular machines, usually as a tube. Single jersey is used for most T-shirts, piqué for polo shirts, interlock for heavier tops, and rib for necklines and cuffs. The greige tube is dyed, then compacted to control shrinkage, and sometimes slit and finished open-width. Bodies are cut in layers, joined on overlock machines, and hemmed with coverstitch. Prints go on as cut panels or on finished garments.
Tirupur in Tamil Nadu is a Town of Export Excellence for hosiery, the trade's name for knitted garments. Knitting, dyeing, compacting, printing and sewing are often done in separate units, which means one fault can be introduced in a unit the garment factory does not control. A tube knitted at a slight angle will twist after washing no matter how well it is sewn.
What we check on T-shirts and knit tops
| Check | How it is checked | What fails |
|---|---|---|
| Fabric weight (GSM) | Round sample cut from a spare panel or offcut and weighed, where you allow it | Below the ordered GSM beyond your tolerance; lighter fabric also affects 16 CFR 1610 testing |
| Side-seam twist | Garment laid flat; side seam position measured against the body at the hem. Wash test where the factory has a machine, or the lab report reviewed | Side seam swinging to the front or back beyond the spec |
| Neck rib stretch and recovery | Neck opening stretched to the minimum head size on the spec, then released and remeasured | Rib that stays stretched, wavy neckline, cracked overlock stitches |
| Measurements | Chest, length, shoulder, sleeve and neck width with the garment flat and relaxed, not pulled | Out of tolerance, or sizes that overlap instead of grading |
| Print stretched across its width; tape pressed on and pulled off; rubbed with a white cloth | Cracking, peeling, colour lifting onto tape or cloth, misplaced or crooked print | |
| Panel shading | Body, sleeves and rib compared side by side under the same light | Sleeve or back a different shade from the front |
| Polo collar and placket | Collar laid flat; placket length and button alignment checked; buttonholes opened | Curling collar tips, crooked placket, uncut or frayed buttonholes |
| Knitting faults | Each panel viewed against light | Holes, needle lines, dropped stitches, barre stripes across the body |
Common T-shirt, polo and knit top defects and how they are classed
| Defect | Typical cause | Class |
|---|---|---|
| Broken needle tip in a garment | Needle snapped during sewing and not recovered | Critical |
| Hole or dropped stitch on the body | Knitting fault not caught at fabric inspection | Major |
| Barre stripes across the body | Yarn from different lots knitted into one roll | Major |
| Side-seam twist after washing | Fabric spirality from knitting and finishing, or panels cut off-grain | Major |
| Shade difference between panels | Panels cut from different dye lots | Major |
| Print cracking on stretch | Ink not cured fully, or the wrong ink for stretch fabric | Major |
| Wavy neck rib | Rib sewn under uneven tension | Minor or major by severity |
| Untrimmed threads at the hem | Thread trimming skipped | Minor |
Your defect list decides the final class.
Market rules for knit tops
- US flammability. Under 16 CFR 1610, plain-surface fabric of 2.6 oz/yd² (about 88 g/m²) or more is exempt from testing. A standard cotton jersey is usually above that. Lightweight slub, burnout and viscose jerseys, and brushed or fleece-backed fabrics, are not exempt and need a lab test.
- US labels. Fibre content by generic name and percentage, country of origin at the inside centre of the neck, the importer's name or RN, and a permanent care label under 16 CFR 423. Elastane is labelled as spandex in the US.
- EU and UK. Fibre names follow Regulation (EU) 1007/2011, where spandex is called elastane. REACH restricts azo dyes and other substances in dyes and print inks.
- Claims. Organic or certified-fabric claims need certificates that match the shipment; see OEKO-TEX and GOTS.
Spirality and shrinkage after washing, colour fastness and pilling are lab tests. We pull samples for them through lab testing coordination.
Packing, transit and your purchase order
Cotton knits that are folded and bagged while still warm or damp from compacting and pressing can develop mildew spots and a sour smell at sea. The inspector feels folded stock for damp, checks that polybags carry any warning you require, and checks the size ratio in each carton against the packing list. Overfilled cartons crush folded tops and crease printed fronts.
- Fabric construction, fibre blend and GSM with a tolerance.
- Maximum spirality and shrinkage after washing, with the test method.
- Neck stretch requirement and rib composition.
- Print method, print size and position, and wash durability.
- Size chart with tolerances and how garments are to be measured.
- Fold, polybag, size sticker and carton assortment.
Sources
- DGFT: Appendix 1B, Towns of Export Excellence (Tirupur, hosiery)
- eCFR: 16 CFR Part 1610, flammability of clothing textiles
- FTC: Threading your way through the labeling requirements under the Textile and Wool Acts
- eCFR: 16 CFR Part 423, Care Labeling Rule
- Regulation (EU) No 1007/2011 on textile fibre names and labelling