Pilling happens when loose fibre ends work out of the yarn, tangle on the surface and stay anchored. Short fibres, low yarn twist, open knit structures and blends with strong synthetic fibres that hold the pills on the surface all make it worse. Friction in wear, under the arms and at the sides, and abrasion in washing speed it up. Some pilling on jersey is normal, but how much depends heavily on the fabric, so it can be specified and tested.

Choose a named method

Two common laboratory methods are ASTM D3512, which tumbles specimens in a random tumble pilling tester, and ASTM D4970, which rubs specimens on a Martindale tester. Both rate the surface against visual standards on a scale where higher numbers mean less pilling. They do not give the same results, so the spec should name one method and keep using it, rather than accepting whichever report the mill already has.

Test after washing too

Because complaints usually appear after washing, it is useful to test fabric that has been washed under a named procedure such as ISO 6330, with the conditions your care label allows, as well as fabric in the as-received state. A fabric that rates well new can behave differently after finishing residues wash out.

What to change if it fails

Options include a longer staple or combed cotton, a higher yarn twist, a tighter knit, a different blend ratio, or finishing such as singeing or biopolishing. Each affects hand feel and cost, so change one thing at a time and retest. Write the agreed minimum rating, the method and the test state into the fabric approval.

Also look at where the pills form. If they appear only under the arms, wear friction dominates and a tougher fabric is the main fix. If the whole garment pills in the wash, washing abrasion and the yarn are the bigger factors.

Record the result in a simple table per fabric lot: method, test state, rating and date. When a reorder comes from a different dye lot or a different mill, the table makes it easy to see whether pilling performance has changed, and it gives the factory a clear, measurable target instead of a subjective description such as 'less fuzzy'. Keep the physical rated specimens too, so the comparison can be repeated by eye.