How to Clean 100% Wool | Without the Shrinkage

100% wool is best cleaned by hand in cool water with a wool-safe detergent, then dried flat away from heat.

For the full breakdown, see our best 100% Wool Coats guide.

Wool is naturally stain-resistant and odor-resistant, which means it needs far fewer washes than your cotton t-shirts. Most of the time, a quick airing is all a wool sweater really needs. But when it does need a proper clean, the process matters — get the water too hot, wring it out, or toss it in the dryer, and that $200 sweater shrinks into a child’s vest.

Whether you can machine wash 100% wool comes down to one thing: the care label. “100% wool” tells you the fiber, not the construction. A loosely knit merino cardigan and a tightly woven wool coat behave very differently in the wash. The golden rule is that you’re never truly done until the garment is dry flat and reshaped while damp.

How to Hand Wash 100% Wool (The Safest Method)

Hand washing is the default for good reason. It gives you total control over agitation, temperature, and treatment.

1. Fill a basin with cool or lukewarm water — never hot. Some wool programs cap the temperature at 30°C (about 86°F), which is a good ceiling for hand washing too.
2. Add a wool-safe detergent and swirl it in before adding the garment. If you’re using powdered detergent, dissolve it completely first — undissolved granules can settle into the weave and create felted spots.
3. Submerge and soak for 3–5 minutes. Gently squeeze the suds through the fabric. Do not scrub, rub, or twist the fibers against each other.
4. Drain and rinse twice using water at the same temperature as the wash water. A sudden temperature change shocks the wool fibers and causes shrinkage.
5. Press out excess water. Lift the garment from the basin and gently squeeze — don’t wring. Roll it in a clean, dry towel and press down to absorb moisture.
6. Dry flat on a fresh towel or drying rack, reshaping the garment to its original dimensions while it’s damp. Keep it out of direct sunlight and away from radiators or heaters.

For a garment that just needs freshening rather than a full clean, skip the basin entirely. Hanging it in the bathroom while you shower lets steam release odors — it’s a gentler reset that extends the time between washes.

Can You Machine Wash 100% Wool?

Yes — but only if the care label explicitly permits it. Many 100% wool garments can handle machine washing on the wool or gentle cycle, and some merino items are even labeled for it. When the label allows it,

What machine washing cannot do is forgive a mistake. The same rules apply: no hot water, no biological or enzymatic detergents (they break down wool protein), and no spin-speed heroics. Unzip all zippers and turn the garment inside out before washing to reduce surface friction. And never machine wash a wool item that says “dry clean only” — the construction isn’t built to survive the agitation whether the label claims 100% wool or not.

If the label gives you the choice, hand washing is still the safer route.

Drying and Care for 100% Wool

Drying is where most wool damage happens. Hanging a wet wool sweater lets gravity stretch the fibers, which permanently deforms the shape. Tumble drying shrinks it — unless the care label explicitly says it’s safe, it isn’t. The short version: flat, out of the sun, away from heat.

Color bleeding is a real concern with dyed wool. A red wool scarf can stain a cream one in a single warm rinse.

If you’re shopping for a new wool piece, consider how you’ll care for it before you buy. A beautifully tailored coat demands a different routine than a machine-washable merino base layer.

FAQs

Does water temperature really matter for wool?

Yes, and it’s usually the reason a sweater shrinks. Hot water causes the wool scales to open and lock together, a process called felting. Keep the water cool to lukewarm — roughly 30°C (86°F) maximum — and keep the rinse water at the same temperature as the wash water to avoid thermal shock.

Can I use regular laundry detergent on wool?

Only if it’s marked wool-safe, mild, or pH-neutral. Standard detergents often contain enzymes or brighteners that break down wool’s protein structure over time, leaving it rough, faded, or weakened. Bleach is never safe for wool. A dedicated wool detergent is a small cost compared to replacing a ruined garment.

Why did my wool sweater shrink even though I used cold water?

Agitation and drying usually cause shrinkage, not just temperature. Twisting, wringing, or rubbing the fibers while wet enables felting, and tumble drying accelerates it further. Squeezing, rolling in a towel, and drying flat are the protection measures — cold water alone isn’t enough.