Wash wool at 86°F (30°C) or cooler, in a pH-neutral detergent, with as little movement as you can manage, and dry it flat. Those four conditions are the whole method. Break any one of them and the fiber may felt, which is a permanent change rather than a bad wash.
Why wool felts, and what that means for the drum
A wool fiber is covered in overlapping scales. Warm water opens them, agitation makes them slide past each other in one direction only, and they lock. The result is felt: denser, smaller and impossible to reverse, because the fiber has changed rather than the stitch. A wool cycle works by using very little water and a slow, shallow drum action, so the garment is cushioned and barely moves.
Two labels change the rules. Superwash wool has been treated with a polymer or stripped of its scales, so a machine wash is genuinely safe, though a hot dryer will still ruin the shape. And a blend with more than about 10 percent synthetic fiber behaves differently again, because the synthetic content holds shape while the wool around it shrinks, which shows up as a pilled, lumpy surface rather than an obviously smaller sweater.
Wash and dry, by fiber
| Fiber | Wash | Dry | Never |
|---|---|---|---|
| Lambswool, Shetland | Wool cycle at 30, pH-neutral detergent | Flat, reshaped, away from heat | Chlorine bleach, a hot dryer |
| Fine merino, superwash | Wool cycle at 30, or a mesh bag | Flat, or a cool tumble if the label allows | A hot dryer and a hot iron |
| Cashmere | Hand wash at 30, five minutes, no rubbing | Roll in a towel, then flat | Wringing, hanging, fabric softener |
| Silk | Hand wash cool, pH-neutral soap, three minutes | Roll in a towel, then flat in shade | Alkaline soap, bleach, wringing, sun |
| Wool with over 10% synthetic | Wool cycle at 30 | Flat | A hot dryer, which sets the creases |
Detergent choice matters more than cycle choice. Standard laundry detergent sits at around pH 9 to 10 and soap is worse, while a wool wash is formulated near neutral so it lifts soil without opening the scales. Fabric softener is the third trap: it coats the fiber, reduces absorbency and leaves a residue that holds odor, which is the opposite of what a wool garment needs. Wool asks for less washing than you'd think; Woolmark notes merino doesn't need washing often and describes wool as naturally odor-resistant.
Cashmere needs less washing than you think
Cashmere is a fine wool with a high crimp and a soft hand, and it pills because short fibers work their way out of the yarn under friction. Washing does not cause the pilling, but rubbing does, so a five-minute soak and a gentle press is the entire job. Air a cashmere sweater between wears, and spot clean the cuffs and collar, which is where it soils first.
De-pill with a comb or a shaver rather than your fingers. Pulling a pill takes the fiber that is anchoring it, which thins the surface and makes the next pill worse. Comb in one direction over a flat surface, and do it after the garment is dry, because damp cashmere stretches as you pull it.
Silk is the one that punishes rushing
Silk loses a significant share of its strength when wet, which is why wringing and hanging are the two things most likely to destroy a silk blouse. Wash cool with a pH-neutral soap for no more than a few minutes, rinse at the same temperature so the fiber is not shocked, then roll the garment in a towel and press out the water rather than twisting it.
Dry silk flat and in the shade, because sunlight fades the dye and degrades the fiber over time. Iron it while it is still just damp, on the lowest setting and with a press cloth, or hang it in a steamy bathroom and let the creases drop out. Dry cleaning remains the right answer for a silk garment with a stain or a lining.
Six things that make wool washing routine
Everything here costs less than two dry cleaning visits, and each removes a way of ruining a sweater. Prices are shown only where we confirmed them on the brand or retailer page in Oct 2026.
Buy this firstWoolovers
Wool wash, 500ml
A neutral liquid that lifts soil without opening the fiber scales, and no rinse means less handling, which is the part that damages wool. Roughly twelve washes per bottle.
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Soak
No-rinse delicate wash, 375ml
Built for the soak-and-press method rather than the wash cycle, with a scent-free version for anyone who reacts to fragrance in a garment they wear against the skin.
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John Lewis
Fine mesh laundry bags, set of 3
A mesh bag cushions a knit inside the drum and keeps a knitted hat or a silk scarf from being pulled out of shape, which is what turns a wool cycle into a safe one.
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Lakeland
Flat drying rack, 3 tier
Wool must dry flat and off a radiator. A rack of mesh shelves holds four sweaters without the shoulder marks a line leaves, and it folds away when the season ends.
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Honey-Can-Do
Cashmere comb
Removes pills by cutting the anchor rather than tugging the fiber out, which is the difference between a surface that recovers and one that thins a little more each season.
Check pricePhilips
Fabric shaver, rechargeable
Faster than a comb on a chunky lambswool sweater and easier on the surface than a razor, which cuts loops rather than lifting the pill away from them.
Check priceWhat it costs against dry cleaning
A bottle of wool wash covers many hand washes, so each wash costs very little. Dry cleaning is priced per garment, and on a cashmere sweater cleaned several times a season, the difference adds up quickly, sometimes to more than a thrifted sweater cost.
The saving only lands if the washing is gentle enough that the garment lasts as long as it would have done otherwise. Wash less often, dry flat every time, and treat the fiber as the thing you are protecting rather than the stain you are removing.
