Pilling is the formation of small balls of tangled fibre on a fabric surface after rubbing in wear or washing. It is tested by rubbing the fabric under controlled conditions and then grading the surface from 1 to 5, where 5 means no pilling, using the ISO 12945 methods, the Martindale and the ICI pilling box, or their AATCC and ASTM equivalents. Buyers usually ask for grade 3 to 4 or better, depending on the end use.
Pills form in three stages. Loose fibre ends work their way to the surface, they tangle into a ball, and the ball either breaks off or stays anchored. Fabrics made from strong fibres such as polyester hold their pills, which is why a polyester cotton shirting can look worse than a pure cotton one even though less fibre has come loose.
What makes a woven fabric pill
- Short staple cotton and carded yarn, which have more loose fibre ends than combed or compact-spun yarn.
- Low twist and low thread density, which leave fibres free to migrate to the surface.
- Polyester and other strong synthetics in blends, which anchor the pills so they do not break off.
- Brushed, peached or sueded finishes, which deliberately raise fibre to the surface.
- Abrasive wear points such as cuffs, underarms and seat areas, where any fabric is under more stress.
How the tests work
In the Martindale method, ISO 12945-2, the fabric is rubbed against itself or a standard abradant in a shifting pattern and assessed at stages, typically up to a few thousand cycles. In the ICI pilling box, ISO 12945-1, specimens are mounted on rubber tubes and tumbled inside a cork-lined box for a set number of hours. ASTM D4970 and ASTM D3512 are the common American counterparts.
After rubbing, the specimen is compared with photographic standards or rated by eye under a standard light and given a grade from 1 to 5, with half grades allowed. Like other visual assessments, results can differ by half a grade between operators, so agree one lab and one method in advance.
Choosing the right spec
Specify the method, the number of cycles or hours and the minimum grade. Grade 4 is a realistic target for combed cotton shirting and most bottom weights, while grade 3 to 3.5 is more usual for brushed or blended fabrics. Ask the mill to test the finished fabric, as a softener or peach finish can change the result considerably compared with the greige.
How we approach pilling
During mill visits we check which yarn the mill is actually using against what was quoted, since a switch from combed to carded yarn is a common cause of pilling complaints. Before loading, we send sealed bulk samples to an NABL-accredited lab for pilling alongside the other tests. If you are unsure which pilling method suits your product, a free 20-minute sourcing review is a good place to start.