Wash 100% wool only according to the garment’s care label, using a wool or cold/delicates cycle with mild detergent for machine-washable items, or a lukewarm hand wash for hand-wash-only pieces.
Wool earns its reputation as a delicate fiber, but that doesn’t mean it’s high-maintenance. The real key to washing 100% wool starts before the water runs: checking the permanent care label sewn into the garment. Under FTC rules, every piece of clothing sold in the U.S. must carry one with regular care instructions, and for wool, that label is the final authority on how to wash 100% wool without turning a favorite sweater into a child-sized version of itself.
What the Care Label Is Telling You
Woolmark, the global authority on wool care, says to wash each garment according to its specific care claim. That label tells you which of three paths your sweater can take: machine washable, hand wash only, or dry clean only. A garment marked dry clean only should never see water — professional cleaning is the only safe route for those pieces.
The care claim matters because not all 100% wool is created equal. Some wool is treated to resist felting and shrinkage, which is why the label — not the fiber content — determines what the garment can handle. Machine-washable wool can go through the washer multiple times without shrinking when the care claim allows it and you follow the right settings.
Machine-Washing Wool: Step by Step
For garments labeled machine washable, Woolmark’s instructions are straightforward and worth following in order:
- Turn the garment inside out before washing to protect the outer surface from friction.
- Sort dark and pale colors separately to cut down on color bleeding.
- Wash on the wool setting if your machine has one — this uses gentle action at about 40°C (104°F). If there’s no wool cycle, use the cold water wash or delicates cycle instead.
- Use a neutral, mild detergent — ideally one that’s Woolmark-approved. Skip heavy-duty, enzyme-based “bio” detergents and bleach entirely; Woolmark warns against both chlorine and oxygen bleaches.
- Powdered detergent should be pre-dissolved in water before it touches the wool.
- Flat dry the garment after the cycle finishes.
Fabric softener is allowed but only sparingly — Woolmark notes that excess softener can encourage pilling in later washes. If you’re shopping for a detergent that’s safe for this step, our tested roundup of the best detergents for wool garments covers the options that won’t damage the fiber.
Hand-Washing Wool the Right Way
For sweaters labeled hand wash only — or anytime you’re unsure and the label permits wet cleaning — fill a clean sink or basin with lukewarm water at about 30°C (86°F). Hot water is the fastest route to shrinkage, so keep it cool. Add a mild, gentle detergent and swish it through the water before adding the garment.
Submerge the wool and let it soak for about 10 minutes. Don’t scrub, rub, or agitate — American Wool’s guidance is clear that rubbing, pulling, and wringing are all off-limits during hand washing. After the soak, drain the soapy water and rinse thoroughly in lukewarm water, then finish with a cold rinse. Press the water out gently rather than wringing, then reshape the garment while it’s still damp.
| Step | Machine Wash | Hand Wash |
|---|---|---|
| Water temperature | 40°C wool cycle or cold | ~30°C lukewarm |
| Detergent | Mild, wool-safe; no enzymes or bleach | Mild, gentle; pre-dissolved |
| Agitation | Wool or delicates cycle only | Soak 10 minutes; no rubbing or wringing |
| Rinse | Machine’s normal rinse | Lukewarm, then cold; thorough |
| Drying | Flat dry | Reshape, then flat dry |
How to Dry Wool Without Ruining It
Drying is where most wool damage happens after a successful wash. Woolmark recommends flat drying for knitwear, and American Wool adds that woven items should dry out of direct sunlight and away from direct heat. Lay the garment flat on a clean towel, reshape it to its original dimensions while damp, and let it air dry naturally.
Skip the tumble dryer entirely unless the care label explicitly allows it. The combination of heat and tumbling is what felts wool fibers together, producing the shrinkage everyone fears. Drying near radiators, in direct sun, or over a clothesline stretched under the sweater’s weight can also distort its shape. Patience here is the whole game — a wool sweater that air-dries flat keeps its fit and feel for years.
FAQs
Does 100% wool always shrink when washed?
No, but the risk depends on the care label. Machine-washable wool is treated to resist felting and can be washed repeatedly without shrinking when you use the wool cycle and cold or lukewarm water. Garments without that treatment shrink when exposed to heat, agitation, or both, which is why the label dictates the safe method.
Can I put 100% wool in the dryer?
Only if the care label explicitly says it’s safe. For most wool garments, tumble drying combines heat with constant agitation — the two factors that felt wool fibers and cause shrinkage or distortion. Woolmark and American Wool both recommend flat drying knitwear and air drying woven items instead.
What happens if I wash wool in hot water?
Hot water accelerates the felting process that tightens wool fibers into a denser, smaller fabric. The result is usually a shrunken, stiff garment. If that happens, the damage is largely irreversible. Always use cool or lukewarm water — around 30°C for hand washing and the cold or wool setting for machine washing.
References & Sources
- Woolmark. “How to Wash Wool.” Official machine-wash and hand-wash instructions, temperatures, and detergent guidance.
- Woolmark. “Care.” Care-label authority and wool garment washing principles.
- American Wool. “Care Tips.” Drying, hand-washing, and bleach-prohibition guidance for wool.