How to wash wool without shrinking it

Woolmark’s pages describe wool that is made to be machine washed without shrinking, and they tie the risk to ignoring the label: a hand wash garment put in a machine, a rougher cycle than the wool is meant for, or a tumble in the dryer. A good wash is a short list of rules. Read the label. Keep the water lukewarm and the handling gentle. Press the water out and never wring. Dry the garment flat. This guide follows the care pages of The Woolmark Company and adds the pest advice from Virginia Cooperative Extension, since clean wool is also moth-safe wool.

Where Woolmark’s pages are silent, this guide says so and does not guess.

Read the care label first

Everything depends on the label. Woolmark says that when a garment’s care claim allows machine washing, it can be safely machine washed in a washing machine multiple times without shrinkage taking place. When it says hand wash, it must be done by hand. The symbols on the label tell you which.

Woolmark’s guide to the symbols sets out the main ones:

• Machine wash, very mild: the label shows 40 degrees Celsius (or 30) and a very mild wash. That is 104 degrees Fahrenheit (or 86). Use a wool or delicates cycle, which reduces mechanical treatment, and fill the drum no more than one third full.
• Hand wash: water between 30 and 40 degrees Celsius at most, which is 86 to 104 degrees Fahrenheit, depending on the garment.
• Do not wash: the garment may be sensitive to any wet treatment, or unsuitable for a home machine. Take it to a dry cleaner.
• Do not tumble dry: Woolmark warns that doing so may cause shrinkage.
• Dry flat: dry the garment lying flat. The steps are further down.

If there is no label, or you cannot read it, wash by hand.

How often to wash

Woolmark’s pages do not say how often wool should be washed, so this guide does not set a rule. Virginia Cooperative Extension sets a floor for moth protection: clean all wool clothing and other woolen items at least once a year, following label precautions, whether you wash at home or use a dry cleaner. Between washes, you can air a garment and treat spills as they happen.

Washing wool by hand

Woolmark’s hand wash, for any garment marked hand wash only and for anything you are unsure of, goes like this.

1. Turn the garment inside out. Woolmark says this prolongs the “as new” look and feel.
2. Fill a clean basin or sink with lukewarm water, about 86 degrees Fahrenheit (30 degrees Celsius), and add a mild, gentle wool detergent. Woolmark prefers one that carries its approval symbol. Dissolve it in plenty of water first.
3. Let the garment float and soak for 10 minutes. Move it gently. Woolmark’s instruction is to agitate carefully, and not to rub, pull or wring out.
4. Rinse thoroughly in lukewarm water, then finish with a rinse in cold water.
5. Press out the excess water. Do not wring. Woolmark says to press the excess water out gently before you reshape the garment.
6. Dry flat, as described below.

Do not leave a wet wool garment lying in the water or in a wet heap. Woolmark’s guidance for colored and delicate pieces is to deal with them quickly and not leave them lying in the wet state.

Washing wool in the machine

Only if the label permits it.

1. Turn the sweater inside out, or put it in a laundry bag.
2. Add a wool detergent, preferably one that is Woolmark approved. Woolmark describes a neutral, mild wool detergent as the way to prolong the life of a favorite sweater.
3. Set the wool cycle. Woolmark says the wool setting is usually a gentle action at 40 degrees Celsius, which is 104 degrees Fahrenheit. If your machine has no wool cycle, Woolmark advises the cold water wash, or the cycle for delicates.
4. Do not overfill. The symbol guide says the drum should be no more than one third full.
5. Take it out as soon as the cycle ends.

Woolmark gives no spin speed. Many machines let you choose a lower spin or switch it off, and with wool that is the cautious choice, but it is an inference and not Woolmark’s instruction.

What to avoid

• The wrong machine setting. Woolmark’s symbol guide ties the very mild wash to reduced mechanical treatment. A normal cycle is rougher.
• A garment marked hand wash only, put in the machine. The label says no.
• Tumble drying, unless the label permits it. Woolmark says tumble drying a garment not marked for it may cause shrinkage.
• Wringing, rubbing and pulling. Woolmark’s instruction is not to rub, pull or wring out.
• Hanging a wet sweater. Woolmark says line drying or drying on hangers can cause knitted garments to stretch, and wire hangers are particularly bad for this.
• Ammonia. UGA Cooperative Extension warns that ammonia damages silk and wool.

Woolmark’s pages that I checked do not cover fabric softener or bleach, so this guide has nothing to say about them. Stay with a wool detergent.

Drying wool

Woolmark’s advice for drying a sweater is to dry it flat.

1. Lay it on a towel. Use a pale or white towel that is free of lint.
2. Shape it. Knead the towel into the shape and size of the garment by hand, and smooth out as many creases and folds as you can.
3. Pin it only if you must, and use pins that are totally rustproof.
4. Keep it out of sun and heat. Woolmark says to flat dry out of direct sunlight, and to avoid direct heat and radiators. It suggests the shade.
5. Do not hang it. Line drying or drying on hangers can stretch knitted garments.
6. Use a mesh drying rack if you have one. Woolmark says the mesh screens that fit over a bathtub tend to speed up drying.
7. Do not tumble dry unless the sweater’s care claim says it can be.

If an area has come out misshapen, such as the shoulders, Woolmark’s one reshaping tip is to dip the area in warm water, 86 to 104 degrees Fahrenheit (30 to 40 degrees Celsius), and massage it gently by hand.

None of the Woolmark pages I checked say how to reverse shrinking. If a sweater has shrunk in the wash, the honest answer is that these sources give no fix. Take it to a dry cleaner or a tailor and ask what is possible.

Stains on wool

Wool does not like to be rubbed, so treat a spill by blotting. Woolmark’s stain guide says to scoop or blot any excess quickly using a white tissue or an absorbent towel, to apply small amounts of liquid treatment and blot well, and to work from the edge of the stain toward the center. Its guidance includes not rubbing with clean tissue after each application. For black coffee, it says to rinse under cold running water immediately to dilute it.

Wool, moths and storage

Moth larvae feed on wool. Virginia Cooperative Extension says only the caterpillars, and not the adult moths, damage woolen fabrics, and that damage is more likely on items that are not frequently used or cleaned. Wash or dry clean wool before you put it away for the season, and store it in a tight-fitting chest or an airtight plastic container, which is what Virginia Cooperative Extension advises. The guide to organizing a closet covers the seasonal swap, and the one on getting rid of clothes moths covers what to do if you find larvae. Note that UC IPM’s moth-killing wash is in water at least 120 degrees Fahrenheit, which is hotter than the 104 degrees Fahrenheit that Woolmark’s symbol guide allows for wool, and for woolens that cannot take hot water it advises dry cleaning.

If a wool shirt or sweater has a sweat mark, see the guide on removing sweat stains and yellowing, which covers why ammonia needs care on wool.