How to wash wool, knitwear and delicates without shrinking them
By the Pacco Pacco Laundry team · Updated 18 September 2026 · 5 min read
The short answer
Wool shrinks through felting: heat, agitation and sudden temperature changes make the fibre's microscopic scales lock together, and the process is permanent. Wash wool cold or at 30°C on a dedicated wool cycle or by hand, with wool detergent, never wring it, and always dry it flat. If a knit is structured, lined or labelled dry clean only, felting risk is exactly why that label is there.
Why does wool shrink? Felting, explained once
Wool fibres are covered in tiny overlapping scales, like roof tiles. Heat and moisture lift those scales, and agitation then ratchets neighbouring fibres past each other until the scales interlock. The fabric pulls tighter and denser and cannot be pulled back, because millions of microscopic barbs are now hooked together. That's felting, and it's why a jumper that met a normal warm cycle comes out two sizes smaller and oddly stiff.
Understanding that mechanism makes every wool rule obvious: avoid heat, avoid agitation, avoid rubbing, and avoid shocking the fibre with big temperature swings between wash and rinse.
Hand washing that doesn't wreck the knit
Fill a basin or trough with cool water and a small amount of wool detergent (the labels say wool wash; ordinary detergents contain enzymes that literally digest protein fibres like wool and silk). Submerge the garment, press gently to move water through it, and leave it for ten minutes. No scrubbing, no swishing back and forth.
Rinse in water of the same temperature, then press the water out against the side of the basin. Never wring or twist. Roll the garment in a clean towel and press to blot the remaining water before drying.
Can you machine wash wool? Yes, carefully
Modern front loaders with a dedicated wool cycle are genuinely safe for most machine-washable and even hand-wash-labelled knits. The cycle uses cold or 30°C water, minimal drum movement and a gentle spin. Put the knit in a mesh bag, use wool detergent, and wash it with other lightweight items rather than alone in an empty drum where it can be thrown around.
What the machine can never do safely is dry it. No wool in the tumble dryer, ever; that's the single fastest way to felt a garment.
Dry flat, and store smart
Wet wool is heavy, and hanging it stretches shoulders and hems permanently. Lay knits flat on a towel or a mesh drying rack, gently pushed back into shape, away from direct sun and heaters. They take a day or two; patience is part of the deal.
Between wears, fold knits rather than hanging them, and air them after wearing instead of washing every time; wool is naturally odour-resistant and overwashing ages it faster than wearing does.
When a knit is a job for the professionals
Structured or lined knitwear, coats, anything with beading, and blends you can't identify are safest professionally cleaned. And if a treasured jumper has already shrunk, be wary of internet miracle fixes: a soak in water with hair conditioner can relax mild shrinkage slightly, but true felting is permanent, and honesty beats false hope.
You can add dry cleaning or a gentle hand-wash request to any Pacco Pacco pickup; flag the item when you book and we'll confirm the right treatment, and the price, before any work is done.
Quick questions
Can I unshrink a felted jumper?
Not really. A 30-minute soak in lukewarm water with hair conditioner, followed by gentle stretching and flat drying, can ease mild shrinkage, but felted fibres are physically locked together and won't return to their original size.
Is the hand-wash label safe to machine wash on a wool cycle?
Usually yes in a modern front loader, inside a mesh bag with wool detergent. The risk isn't zero, so make that call only on garments you could bear to lose, and never for structured or lined pieces.
Why can't I use normal laundry detergent on wool?
Most standard detergents contain protease enzymes that break down protein, which is what wool and silk are made of. Over time they weaken and thin the fibre. Wool washes are enzyme-free and pH-neutral.