How to Wash a Sweater Without Shrinking It (Wool, Cashmere and Cotton)

It went into the wash a size medium and came out fitting a ten-year-old. Almost everyone has shrunk a favorite sweater once, and it is the reason so many knits end up on the "dry clean only" pile. To wash a sweater without shrinking it, use cool or lukewarm water, a gentle wool or delicates detergent and as little agitation as possible, never wring it, rinse at the same temperature, and dry it flat away from heat. Above all, keep wool and cashmere out of the tumble dryer. Below is why sweaters shrink, how to hand wash and machine wash safely, how to dry and reshape them, whether a shrunken sweater can be saved, and why a light pass with a 2-in-1 steamer and iron is safer for knits than a hot iron.

Why do sweaters shrink in the wash?

It depends on the fiber. Wool and other animal fibers, such as cashmere, alpaca and angora, have tiny scales on their surface. Heat, moisture and agitation together make those scales catch and lock onto each other, so the fibers mat and pull closer together. This is called felting, and once it happens it is very hard to undo. Cotton sweaters shrink differently: the fibers relax and tighten with heat, especially in a hot dryer. Acrylic and other synthetics rarely shrink, but high heat can stretch or distort them instead.

So the three things to control are temperature, agitation and drying.

How do you hand wash a sweater without shrinking it?

Hand washing is the safest method for wool and cashmere. Always check the care label first.

1. Fill a basin with cool or lukewarm water, never hot, and add a small amount of wool or delicates detergent.
2. Turn the sweater inside out and press it gently under the water.
3. Let it soak for about 10 minutes. Squeeze the suds through gently; do not rub or scrub.
4. Rinse in water of the same temperature. A sudden change from warm to cold can encourage felting.
5. Press the water out by squeezing gently. Never wring or twist.
6. Roll it in a towel: lay the sweater flat on a clean towel, roll them up together and press to absorb more water.

Can you machine wash a sweater without shrinking it?

Yes, if the care label allows it and your machine has a wool, hand-wash or delicates cycle with cold water and a low spin. To protect it further:

• Turn the sweater inside out and put it in a mesh laundry bag so it does not stretch or snag on zips and hooks.
• Wash it with other light, soft items rather than heavy jeans and towels.
• Use cold water and a wool or gentle detergent.
• Choose the lowest spin speed available.

Our mesh laundry bags come in a set of seven, including a roomy 60 x 60 cm bag that suits a sweater. Fill each bag loosely, about two-thirds full, so water can move through the mesh.

How do you dry a sweater so it does not shrink?

Flat, away from heat. Lay the sweater on a dry towel or a mesh drying rack, gently pull it back to its original shape and size, and smooth the sleeves, hem and neckline. Turn it over once the top is dry. Keep it away from radiators, heaters and direct sun.

Do not hang a wet sweater, because the weight of the water stretches the shoulders and lengthens the body. And unless the label clearly says it can be tumble dried, keep it out of the dryer; that is where most shrinking happens.

Does steaming shrink sweaters?

No, light steaming does not shrink a sweater when you hold the steamer just above the fabric. Shrinking comes from soaking, agitation and sustained heat together, as in a hot wash or dryer. A short pass of steam actually helps knits: it relaxes creases from storage and lifts flattened fibers. With a handheld steamer and iron such as the RosyIron SteamerPro, use the Silk setting for cashmere and fine knits and Blend for wool, steam from just above the fabric rather than pressing down, then let the sweater rest flat for a minute. Our guide on how to steam wool and cashmere has the full method.

Can you unshrink a sweater?

Sometimes, partly. If a wool sweater has only shrunk a little, this mainstream method can help it relax:

1. Soak it for about 30 minutes in lukewarm water with a spoonful of gentle hair conditioner or baby shampoo.
2. Press out the water without wringing, and roll it in a towel.
3. Gently stretch it back toward its original size, a little at a time, and lay it flat to dry. Some people pin it to a towel or weigh the edges.

Be realistic: a sweater that has felted, with a thick, stiff, fuzzy texture, will not fully return to its old size. Cotton sweaters can often be eased back more easily while damp.

How to wash a sweater at a glance

Fiber	Wash	Dry	Shrink risk
Wool	Hand wash or wool cycle, cool water	Flat, no dryer	High with heat and agitation
Cashmere	Hand wash, cool water, gentle detergent	Flat, no dryer	High
Cotton	Cold, gentle cycle	Flat or low heat if the label allows	Medium, mostly in the dryer
Acrylic and blends	Cold or warm, gentle cycle	Flat or low heat	Low, but can stretch

FAQ

What water temperature shrinks sweaters?

Hot water is the biggest risk, especially combined with agitation. Cool or lukewarm water is safest for wool and cashmere, and keeping the wash and rinse at the same temperature helps.

Can I wash a "dry clean only" sweater at home?

Sometimes, but it is at your own risk. Many wool and cashmere knits labeled dry clean only can be hand washed gently, but structured or mixed-fabric pieces should go to a dry cleaner. Test on a hidden area if you are unsure.

How often should you wash a sweater?

Less often than you think. Wool and cashmere can be worn several times between washes; air them out on a flat surface and spot clean small marks.

Does the dryer always shrink wool sweaters?

It is the most common cause. Unless the label clearly says the sweater can be tumble dried, dry it flat.

Wash gently, wear for years

Most shrunken sweaters are the result of one hot wash or one trip through the dryer. Cool water, a gentle touch and drying flat keep knits the size you bought them. When they come out of storage or a suitcase with creases, a light steam from just above the fabric with the RosyIron SteamerPro 2-in-1 steamer brings them back without a hot iron.