How to Wash Woollens Without Shrinking Them

Why Woollens Shrink in the First Place

Wool is a remarkable fibre, but it is also a delicate one. Under a microscope, each wool fibre is covered in tiny overlapping scales, rather like roof tiles. When those scales are exposed to heat, agitation and alkaline detergents, they lock together and the fabric tightens permanently. This is called felting, and unlike simple shrinkage, it cannot be undone.

The second problem is weight. Wet wool is heavy, and if you lift a soaking jumper by the shoulders or hang it up to dry, gravity stretches it out of shape. So the golden rules are simple: keep the water cool, keep the movement gentle, and never let a wet woollen garment hang. Get those three things right and most jumpers, cardigans and scarves will come out soft, fresh and exactly the size they went in.

Check the Care Label Before Anything Else

Before you fill a basin, read the label inside the garment. Most woollens will fall into one of three categories, and each needs a different approach.

• Hand wash only: treat it gently in a basin, as described below.
• Wool cycle or delicate: a modern machine wool programme is often gentler than hand washing, because it controls temperature and agitation precisely. Follow it.
• Dry clean only: usually reserved for structured tailoring, heavily embellished knits or unusually fine fibres. Respect it.

It is also worth testing for colour bleed on an inside seam with a damp white cloth. If dye transfers, wash the item alone or with similar dark shades.

Hand Washing Woollens Step by Step

Fill a clean basin or sink with cool water — below 30°C, and ideally around 20°C, which feels barely tepid on your wrist. Hot water is the single biggest cause of shrinkage.

Add a pH-neutral wool detergent or, if you have none to hand, a small squeeze of baby shampoo. Avoid biological powders, enzyme cleaners, bleach and fabric conditioner, all of which damage wool fibres. Conditioner in particular coats the scales and strips out the natural bounce.

• Submerge the garment and let it soak for 10 to 15 minutes. Do not scrub, rub or twist.
• Gently squeeze the sudsy water through the fabric with flat hands, then drain the basin.
• Refill with water at exactly the same temperature. A sudden change from cool to cold can shock the fibres and cause felting.
• Rinse until the water runs clear, again pressing rather than wringing.
• Lift the garment with both hands supporting the whole weight, never by one shoulder.

Using a Machine Wool Cycle Safely

If your machine has a wool or hand-wash programme, it is a genuinely good option for everyday knits. Set the temperature to 30°C or lower and reduce the spin speed to 400–600 rpm — a fast spin is the machine equivalent of wringing.

• Use a liquid detergent formulated for wool, never a powder with enzymes or brighteners.
• Place the garment inside a mesh laundry bag for extra protection.
• Wash with similar colours and textures, and keep the drum half full at most.
• Skip the fabric conditioner compartment entirely.

Never use a standard cotton cycle, even on a cold setting. The long agitation phase is what ruins woollens.

Drying Flat Is Non-Negotiable

Tumble dryers are off limits for wool. So is a washing line, a radiator and the back of a chair. All of them let the weight of the wet garment pull the fibres downwards, and the heat from a radiator can felt the surface.

The reliable method is to lay the garment flat. Press the excess water out against the side of the basin, then lay the item on a clean bath towel, roll the towel up loosely and press down to blot out more moisture. Unroll, lift the garment with both hands and place it on a fresh dry towel or a mesh drying rack. Smooth it back into shape, matching the original measurements, and pat the seams straight.

Dry it somewhere airy, out of direct sunlight and away from radiators. Turn it over once or twice so both sides dry evenly. A mesh airer is ideal because air circulates underneath. It may take a day or two, but that slow drying is exactly what keeps the fit true.

Washing Less Often, and Rescuing a Shrunken Jumper

Wool is naturally odour-resistant and self-cleaning to a degree, so it rarely needs a full wash. Airing a jumper on a hanger for 24 hours, or spot-cleaning a mark with a damp cloth, will keep it fresh for several wears. When you do store woollens, fold rather than hang them, and tuck in a few cedar balls or a lavender bag to deter moths. Always store them clean, since food stains and sweat attract larvae.

If a jumper has already shrunk slightly, all is not lost. Soak it in cool water with a generous squeeze of hair conditioner for about 30 minutes. The conditioner relaxes the fibres, allowing you to stretch the garment gently back towards its original size. Work slowly, section by section, then dry it flat as described. It will not fix serious felting, but it has rescued many a favourite knit.