Pills are small balls of tangled fibers that form on the fabric surface during wear and washing. They make garments look old and are a common reason for customer complaints, especially on knits, fleece and blends. Pilling tests simulate wear in the laboratory and grade the result.
How pills form#
- Fuzzing: rubbing pulls fiber ends out of the yarn to the surface.
- Entangling: the loose fibers tangle into small balls.
- Wear-off or anchoring: weak fibers (such as cotton) let pills break off; strong fibers (such as polyester) hold them on the surface.
That is why polyester-cotton blends often pill more visibly than 100% cotton: the polyester anchors the pills.
Common test methods#
| Method | Principle |
|---|---|
| ISO 12945-1 | Pilling box: specimens on tubes tumble in a cork-lined box |
| ISO 12945-2 | Modified Martindale: specimens rubbed against fabric in a figure-of-eight pattern |
| ISO 12945-3 | Random tumble pilling |
| ASTM D3512 | Random tumble pilling tester |
| ASTM D4970 | Martindale tester |
The method, the number of cycles or revolutions and the assessment points are specified by the buyer. Results from different methods are not comparable.
Grading#
After the test, specimens are compared with photographic standards or described grades, usually in a viewing cabinet with light at a low angle to show the surface:
| Grade | Description |
|---|---|
| 5 | No change |
| 4 | Slight surface fuzzing or partially formed pills |
| 3 | Moderate pilling |
| 2 | Distinct pilling |
| 1 | Dense pilling covering the specimen |
Half grades are used. Some buyers assess at more than one stage, such as after a lower and a higher number of cycles.
Why fabrics pill#
| Factor | Effect |
|---|---|
| Short fibers | More fiber ends, more fuzz |
| Low yarn twist | Fibers pulled out more easily |
| Hairy yarns (such as open-end or carded) | More surface fibers |
| Strong synthetic fibers | Pills anchored on the surface |
| Loose fabric structure | Fibers move and escape more |
| Brushed or raised surface | Many loose fibers already on the surface |
| Harsh washing | More abrasion |
Improving pilling resistance#
- Yarn: longer fibers, combed or compact yarns, suitable twist.
- Fiber: low-pill polyester variants in blends.
- Fabric: tighter construction (shorter stitch length in knits, higher density in wovens).
- Finishing: singeing to remove surface fibers; biopolishing (cellulase enzyme treatment) on cotton; shearing on brushed fabrics; anti-pilling finishes.
- Garment care: care labels that recommend washing inside out and gentle cycles can help, but they do not replace a good fabric.
Practical tips#
- Test finished bulk fabric, because finishing changes pilling a great deal.
- Test both sides of fabrics where the back will be exposed, such as fleece.
- For fabrics that barely pass, check whether the result holds after washing as well.
See pilling for garment complaints and troubleshooting.
Related guides#
- ISO, ASTM and AATCC test methods: pilling methods by standard.
- Fleece fabric: the brushed fabric most prone to pilling.
- Single jersey fabric: jersey made from short-staple or open-end yarns.
- French terry fabric: looped-back fabric and its surface.
- Fabric testing standards and methods: pilling within the full test program.
- Sustainable bio-scouring process: enzyme processing, often paired with bio-polishing against pilling.
Frequently asked questions#
Why do my lab results differ from what customers see? Laboratory tests simulate wear under fixed conditions. Real wear varies with use, washing and friction points (underarms, thighs, bag straps).
Does fabric softener change pilling? Some finishes change the result; test the fabric as it will be sold.
Should I test after washing? Some buyers require pilling tests after a set number of washes, because washing can raise fibers and change results.