How to Wash a Wool Sweater by Hand or Machine (Without Shrinking It)

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Wool sweaters shrink when three things meet: warm water, agitation and a sudden temperature change. Avoid those and wool is easy to wash. The first thing to know is whether your sweater is superwash wool, which tolerates a machine wool cycle, or untreated wool, which should be washed by hand.

Protein fibers like wool are the most delicate fibers a dyehouse handles, and I have worked with them for 14+ years. This guide covers both methods and explains the reasons behind each step.

Step 1: read the care label

Label says	What it means	How to wash
Machine washable, superwash, or a wool cycle symbol	Treated wool that resists felting	Cold wool or delicate cycle, wool detergent, dry flat
Hand wash	Untreated or loosely knit wool	Basin, cool water, wool detergent, dry flat
Dry clean only	Construction, trims or dyes may not tolerate water	Dry clean, or spot-clean between cleans

How to hand wash a wool sweater

1. Turn it inside out to protect the face of the knit.
2. Fill a basin with cool to lukewarm water, no warmer than about 30°C (86°F), and dissolve a little wool detergent.
3. Submerge and soak for 10 minutes. Press gently a few times. Do not rub or twist.
4. Rinse in water of the same temperature. Temperature shock encourages felting.
5. Press out the water against the side of the basin, then roll the sweater in a towel and press.
6. Dry flat on a towel or rack, reshaped to its original size, away from heat and sun.

How to machine wash a wool sweater

1. Only do this if the label allows it, or the sweater is superwash.
2. Turn it inside out and place it in a mesh laundry bag.
3. Choose the wool or hand-wash cycle with cold water and the lowest spin.
4. Use a wool detergent; avoid enzyme (bio) detergents and fabric softener.
5. Wash with other wool or alone, never with towels or jeans.
6. Take it out promptly and dry it flat.

What not to do

• Do not use hot water or a normal cycle.
• Do not tumble dry; even low heat can shrink untreated wool.
• Do not wring or hang a wet sweater; the weight of the water stretches it.
• Do not use bleach or enzyme detergents; they damage protein fibers.

How often should you wash a wool sweater?

Wool resists odor naturally. Air it between wears, spot-clean small marks and wash it every five to ten wears, or sooner if it is stained or worn next to skin. Over-washing wears it out faster than wearing it.

Related guides

• How to wash a cashmere sweater
• Merino wool vs cashmere
• Will clothes shrink in the dryer? on our sister site

Frequently asked questions

Can you put a wool sweater in the washing machine?

Only if the label allows it or it is superwash wool. Use a cold wool cycle, a mesh bag and the lowest spin, then dry flat.

What detergent is best for wool?

A pH-neutral wool detergent without enzymes. A mild hair shampoo works in an emergency.

Why did my wool sweater shrink?

Usually warm water, agitation or tumble drying caused the fibers to felt. Felting is largely permanent.

How do you dry a wool sweater?

Press the water out, roll it in a towel, then lay it flat and reshape it. Keep it away from heat and direct sun.