How to Unshrink a Jumper (Sweater) That Shrank in the Wash

A shrunken jumper (sweater) can often be eased back towards its old size: soak it for about 30 minutes in lukewarm water with a spoonful of hair conditioner or baby shampoo, press the water out in a towel, then gently stretch it and dry it flat. The conditioner method works best on wool and cashmere that have shrunk only a little, gives more modest results on cotton, and usually cannot fully restore a jumper that has felted into thick, stiff fabric.

Why do jumpers shrink in the wash?

Wool and other animal fibres are covered in tiny overlapping scales. Heat, water and rubbing make those scales catch on each other and lock together, which pulls the knit tighter and smaller. Taken far enough, the process is called felting, and it is the same thing makers do on purpose to produce felt.

Cotton shrinks for a different reason. The fibres are pulled taut when the yarn is spun and the fabric is knitted, and hot water and a hot dryer let them relax back to a shorter length. Synthetic fibres such as acrylic and polyester shrink much less in water, although high heat can distort them.

Can a shrunken jumper be fixed?

Often, yes, but how much you get back depends on the fibre and on how far the shrinking went. Before you start, lay the jumper flat and look closely at the knit.

• Good chance: the fabric still feels soft, you can see individual stitches, and it has lost a size or so in length or width.
• Partial result likely: the knit feels denser and slightly fuzzy, but the stitches are still visible if you stretch it gently.
• Unlikely to recover: the jumper feels thick and stiff, the stitches have merged into a solid surface, and it springs back when pulled. That is felting, and the scales have locked too tightly to release.

Even a felted jumper may give back a little length or width, so the soak is still worth a try. Just set your expectations accordingly.

What you need

• A clean sink, basin or bucket big enough to submerge the jumper
• Hair conditioner or baby shampoo (a gentle, unscented one is best)
• Two large, clean bath towels
• A flat drying rack, or a spare towel on a table
• A tape measure, or an old jumper that fits you well to use as a template
• Optional: rustproof pins or a few heavy books to hold the edges in place while it dries

How to unshrink a jumper with conditioner, step by step

1. Check the label. Note the fibre content and any care instructions. If the label says dry clean only, a specialist cleaner may be the safer route for an expensive piece.
2. Fill the basin with lukewarm water. Aim for roughly body temperature, so it feels neither warm nor cold on your wrist. Stir in one to two tablespoons of conditioner or baby shampoo until it dissolves.
3. Soak for about 30 minutes. Push the jumper under, press it gently so the water soaks through, then leave it. Do not rub, scrub or wring it, because agitation is what tightens wool fibres.
4. Drain without rinsing. Let the water out and press the jumper against the side of the basin to remove the worst of it. Leaving the conditioner in helps the fibres stay supple while you stretch them.
5. Press it in a towel. Lay the jumper flat on a dry towel, roll the towel up like a Swiss roll, and press down along the roll. The jumper should end up damp, not dripping.
6. Stretch it gently. Unroll it onto the second dry towel. Working a little at a time, ease the body lengthways and widthways, then the sleeves, then the cuffs and hem. If you have a template jumper, lay it underneath and stretch towards its outline.
7. Hold the shape. Pin the edges to the towel or rack, or weigh down the hem and cuffs with books, so the jumper cannot shrink back as it dries.
8. Dry flat and reshape. Leave it somewhere airy, away from radiators and direct sunlight. Every hour or two, give it another gentle stretch while it is still damp.
9. Repeat if needed. If it is closer but still too small, you can do the whole process a second time once it is dry.

How hard should you stretch?

Stretch only until you feel resistance, then hold for a few seconds and move on. Wet wool is weaker than dry wool, and pulling hard in one spot can thin the knit or leave a bulge. Several gentle passes do more good than one forceful one.

Does the conditioner method work on cotton?

It helps a little, but cotton does not respond as well as wool. There are no scales to relax, so what you are doing is gently pulling relaxed fibres back out while they are wet. You can usually regain some length in the body, and ribbed cuffs and hems tend to be the most stubborn.

With a cotton jumper, follow the same soak, then stretch it firmly but evenly while damp. Pinning it out to dry makes more difference with cotton than with wool, because cotton tends to creep back to its shrunken size as it dries.

What about cashmere, merino and blends?

Cashmere and merino

Both are fine, soft wools and usually respond well to the conditioner soak. They are also more delicate than a standard wool jumper, so handle them lightly, keep the water lukewarm and support the whole weight of the jumper when you lift it out of the basin.

Wool blends

A jumper that mixes wool with nylon or acrylic may partly recover. The wool portion relaxes, but the synthetic portion may hold its new shape, so results vary from piece to piece.

Acrylic and polyester

Water and conditioner will do very little here. Some people carefully use a steam iron held just above the fabric while stretching, but heat can permanently soften acrylic so that it goes limp and loses its bounce. If you try it, test on an inside seam first and keep the iron moving.

What if the jumper cannot be saved?

A fully felted wool jumper is still useful. Felted wool does not fray when cut, so it works well for mittens, a hot-water bottle cover, coasters or a cushion front. If it is simply a size or two too small, it may fit a younger family member or a friend.

How can you stop jumpers shrinking again?

• Wash wool and cashmere by hand in cool water, or on your machine’s wool or hand-wash cycle.
• Use a detergent made for wool. Many standard detergents contain enzymes that are designed to break down protein, and wool is a protein fibre.
• Never tumble dry knitwear unless the label clearly says you can.
• Dry jumpers flat. Hanging a wet jumper lets the weight of the water stretch the shoulders and body out of shape.
• Wash knitwear less often. Airing it out between wears is often enough.

If a jumper was already snug before it went in the wash, the real fix may be the next size up. Our men’s clothing size converter shows how US, UK and EU sizes line up, which helps when a brand sizes small. For more washing and storage advice, the Luxeurs Journal has other clothing care guides, and if a favourite piece is past saving you can look through the knitwear in our shop.

FAQs

Can you unshrink a sweater that has felted?

Not fully. Once the wool fibres have matted into felt, the scales are locked together and a soak will only loosen them slightly. You may get back a little size, but the fabric will stay thicker and stiffer than before.

Is hair conditioner or baby shampoo better for unshrinking wool?

Both do the same job of softening the fibres so they are easier to ease back into shape. Use whichever you have, and choose a mild, unscented one if you can so no strong fragrance is left in the jumper.

Should I rinse the conditioner out afterwards?

Most people leave it in, because it keeps the fibres pliable while you stretch and dry the jumper. If the finished jumper feels greasy, give it a quick dip in cool, clean water and press it dry in a towel.

Can I use a hairdryer to speed up drying?

It is better not to. Direct heat can tighten wool again and undo the stretching you have just done. Let it dry naturally in a well-ventilated room, even if that takes a day or more.

How many times can I repeat the soak?

You can repeat it two or three times on a jumper that is getting closer to the right size. If nothing has changed after a second attempt, the fibres have probably felted and further soaking is unlikely to help.