How to rescue a shrunken wool jumper (and when you cannot)

To rescue a shrunken wool jumper, soak it for about half an hour in lukewarm water with a generous squeeze of hair conditioner, which helps the fibres relax. Then press out the water without wringing, lay the jumper on a towel and gently stretch it back towards its old size, a little at a time. Leave it to dry flat, reshaping it as it dries. This can win back some of the lost size on a jumper that has shrunk a little. It cannot undo heavy felting, where the knit has turned thick and stiff.

It is worth trying before you give up on a favourite jumper, or before you pass up a second-hand one that has come out of the wash a size smaller. Here is how, and how to tell whether it is worth the effort.

Why wool shrinks

Wool fibres have tiny scales along their length. Heat, agitation and sudden changes of temperature make those scales lock together, pulling the knit tighter. Washed gently, the fibres stay loose. Washed hot or tumbled, they can lock permanently. This is called felting.

Shrunk or felted? Check first

Look closely at the knit.

Shrunk a little: the jumper is smaller, but you can still see the individual stitches clearly and it still feels soft and stretchy. This is the kind that can often be helped.
Felted: the stitches have blurred into a dense, fuzzy fabric, and the jumper feels thick and stiff. You may win back a little size, but it will not return to how it was.

Pure wool, merino and cashmere all respond to this method. Wool blended with acrylic or nylon tends to shrink less in the first place, and it may not stretch back as well either.

What you need

a clean basin or sink
lukewarm water
hair conditioner, or a gentle baby shampoo
two or three clean, dry towels
a flat surface to dry on
a tape measure, and ideally a jumper that fits you, as a guide

Step by step

Fill the basin with lukewarm water. Not hot, which would make things worse, and not cold.
Mix in a tablespoon or two of hair conditioner until it dissolves.
Submerge the jumper and press it gently under the water. Leave it to soak for about 30 minutes.
Do not rinse it yet. Lift it out and press the water out gently against the side of the basin. Do not wring or twist.
Roll it up in a dry towel like a sausage and press to soak up more water. It should be damp, not dripping.
Lay it flat on a fresh towel. If you have a jumper that fits, lay it next to it as a guide.
Ease it back to size. Gently stretch the body widthways and lengthways, then the sleeves, a little at a time. Work evenly so it does not end up lopsided.
Hold it in shape while it dries. Some people use heavy books or rustproof pins along the edges to keep it stretched. Check the shape every hour or so for the first few hours.
Let it dry fully, flat and away from radiators and direct sun. This can take a day or two.

Once it is dry, if it feels a little soft or slippery from the conditioner, give it a quick, cool rinse and dry it flat again, reshaping as before.

Tips that help

Be patient. Gentle stretching over two or three goes works better than one hard pull.
Measure as you go. Compare chest and length with the jumper that fits.
Focus on the parts that matter. Sleeve length and body length are often what makes a shrunk jumper unwearable.

What not to do

Do not use hot water. It will tighten the fibres further.
Do not tumble dry it, even to speed things up.
Do not hang it to dry. The weight of the water stretches it unevenly.
Do not mix products, such as conditioner with detergent or other treatments. One is enough.

If it cannot be saved

A felted jumper still has its uses. Pass it to a smaller friend or family member, or sell it honestly described with its measurements in cm. Felted wool is also useful for craft projects, such as cushion covers, mittens and patches.

How to stop it happening again

Check the care label before every wash. "Hand wash" usually means exactly that.
Use cool water and a wool detergent.
Rinse in water of the same temperature as the wash.
Never tumble dry wool unless the label says you can.

Our guide to washing and storing knitwear covers the full method, and our guide to reading a clothing care label explains the symbols.

Buying second-hand knitwear

Second-hand jumpers may have shrunk at some point, which is why the measurements matter more than the size on the label. Ask the seller for the chest, length and sleeve in cm, laid flat, using Message the seller on the listing, and compare them with a jumper you own. Our guide to measuring clothes for buying online shows how. A close-up photo of the knit also tells you whether it has felted.

For cashmere, our guide to telling if cashmere is good quality covers what else to check.

The short version

Soak in lukewarm water with conditioner, press out the water, stretch it gently back to size on a towel and dry it flat. It works on mild shrinking, not heavy felting. Next time, wash cool, gently and never tumble dry.

Find your next piece

Second-hand clothing from sellers across the UK, with measurements in cm where sellers add them and buyer protection at checkout.

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