Why Sweaters Pill (And How to Stop It)

Most sweaters pill to some extent. It’s a surface issue — short fibers work loose from the yarn under friction and gather where the fabric rubs. Cashmere, cotton, wool, and blends can all pill. Here’s what causes it, what reduces it, and how to lift pills off without damaging the knit.

A pill is a small ball of short fibers that has worked loose from the yarn and tangled on the fabric surface.

Every spun yarn contains fiber ends. Friction teases those ends out of the twist — the crook of your arm against your side, a bag strap on the shoulder, a seatbelt across the chest. Once free, the ends tangle with their neighbors and roll into a ball that stays attached until it’s removed or drops off.

That’s why pills appear in specific places: underarms, the sides of the body, the forearms, wherever a strap sits. It’s a surface issue, not a structural one.

Most new knits shed some loose fiber in the first few wears and then settle down. Pilling that slows after the first few washes is normal.

Cashmere pills partly because its fibers are fine and short. Fineness is what gives cashmere its soft feel.

Cashmere fibers measure 14 to 19 microns across. Merino is 15 to 24. That fineness is what produces the softness — and finer, shorter fibers can work loose more easily than long, coarse ones.

Fiber length plays an important role in how much a sweater pills over time. Longer fibers help reduce shedding and pilling, because more of the fiber stays anchored inside the yarn twist. Quince Mongolian cashmere is knitted from fibers measuring 15.8 to 16.2 microns in diameter and 34 to 36 millimeters in length — both on the finer, longer end of what’s commercially available.

Use a fabric comb for fine knits, or a battery sweater shaver for chunky ones. Lay the sweater flat and work in one direction.

• 1.  Lay the sweater flat on a hard surface. Not on your body, not on a hanger — tension can pull the blade into the knit.

• 2.  Hold the fabric taut with your free hand.

• 3.  On cashmere and fine-gauge knits, use a fabric comb: short strokes, one direction, light pressure.

• 4.  On chunkier knits, a battery sweater shaver works better. Keep it moving, don’t press.

• 5.  Work in sections. Lift the shed fiber away as you go.

Skip scissors and disposable razors — both can cut anchored fibers along with the loose ones, which creates more pills or opens a hole.

Remove pills as needed, using a light touch.

Two things help most: reduce friction, and wash less often.

• •  Check the care label first. If machine washing is allowed, turn the sweater inside out and use a mesh bag to reduce rubbing.

• •  Wash less often. Every cycle creates friction. Wool refreshes when it’s aired, and three to five wears between washes is a good rule of thumb.

• •  For machine-washable knits, use cold water and the wool or delicate cycle.

• •  Skip fabric softener. It coats the fiber and weakens the yarn’s grip.

• •  Rotate your knits. Wearing the same sweater on consecutive days concentrates friction in the same places. A rotation of three or four helps.

• •  Alternate a shoulder bag between sides. A bag on the same shoulder every day will pill that shoulder first.

• •  Fold rather than hang. Hanging stretches the knit and adds friction at the shoulder.

Normal pilling slows down over time. Pilling that keeps accelerating after several washes may point to short fibers or loose yarn twist.

Heavy pilling that persists, or fabric that’s thinning, deserves a closer look.

Micron count and fiber length are useful specs to check before you buy — they predict how a sweater will feel and how well it will hold up. Not every retailer publishes them.