You put your favourite wool hat through the wash and pulled out something unrecognisable — stiff, misshapen, two sizes too small. Or maybe it's fine, but it smells like last winter and you're afraid to touch it. I design wool hats for a living. Every week I answer questions about cleaning, and the answer is almost always the same: wool is forgiving, but only if you respect two rules. No heat. No agitation. Everything else is detail.

This guide covers every cleaning scenario you'll encounter — spot cleaning a sweat stain, hand washing a felt cloche, refreshing a cashmere beanie, treating an oil stain, and storing hats so they don't need cleaning as often. The Master Matrix below tells you which method applies to your hat in under ten seconds.

Master Matrix — Which Method for Which Hat

Why Wool Needs Different Care Than Other Fabrics

Wool fibres are covered in microscopic scales, like overlapping roof tiles running along each strand. Under a microscope they look like a pine cone. In normal conditions those scales lie flat — the fibre is smooth, soft, and resilient. Expose those scales to three things simultaneously — heat, moisture, and agitation — and they lock together. The fibre structure contracts, the hat shrinks, and the process is permanent. This is called felting, and it's exactly what a washing machine cycle on the wrong setting will do in under ten minutes.

The good news is that wool is naturally odour-resistant, dirt-repellent, and self-regulating. The lanolin in wool fibres — a natural wax secreted by sheep — actively resists moisture and bacteria, which is why a quality wool hat can be worn many times between cleanings. Most wool hats don't need washing nearly as often as their owners think. A brush and a proper air-out handles the vast majority of maintenance. Deep cleaning is for genuine soiling, not routine wear.

Method 1 — Spot Cleaning (Most Hats, Most of the Time)

Spot cleaning is the right first response to almost any hat soiling — a mud splash, a food mark, a makeup transfer. It treats the problem area only, without exposing the whole hat to moisture. For felt hats (berets, cloches, structured wool hats), spot cleaning is often the only cleaning method that should ever be used.

The Correct Spot Clean Process

1. Let any fresh stain dry completely first. Trying to wipe a wet mud stain spreads it. Wait until it's fully dry, then brush away the residue with a soft-bristled hat brush before introducing any moisture.
2. Dampen a clean cloth with cold water — not wet, just barely damp. Wring it out thoroughly. Excess moisture on felt can leave water marks that are harder to remove than the original stain.
3. Dab — never rub. Rubbing pushes the stain deeper into the felt and creates a rough patch on the surface. Dab gently from the outside edge of the stain inward, lifting rather than spreading.
4. For anything beyond water alone, add one small drop of wool-safe detergent (Woolite or equivalent) to a tablespoon of cold water. Apply with the cloth, then follow with a clean damp cloth to remove any soap residue.
5. Air dry away from heat and reshape gently while still damp if the area has distorted.

Method 2 — Hand Washing (Full Clean for Knit Hats)

Knit wool hats — beanies, slouchy hats, knit cloches — can be hand washed when spot cleaning isn't enough. The open looped construction of knit wool absorbs and releases moisture more readily than pressed felt, and the elastic structure recovers its shape after gentle handling. This is still a careful process. The rules are the same: cold water, no agitation, no wringing.

Step-by-Step Hand Wash

1. Fill a clean basin with cold water — 20–30°C maximum. Add a small amount of wool-specific detergent: about a teaspoon for a basin of water. Wool wash, Woolite, or a pH-neutral baby shampoo all work. Standard detergent strips lanolin and weakens the fibre over time.
2. Submerge the hat and gently press it beneath the surface. Do not agitate, scrub, or swirl. Let it soak for 10–15 minutes. The water will loosen dirt without mechanical stress on the fibre.
3. Lift the hat out carefully — supporting its full weight with both hands. Wool is significantly heavier when wet and the extra weight can stretch the structure if you lift from one point.
4. Press excess water out gently between the palms of your hands. Do not wring or twist. Lay the hat flat on a clean dry towel, roll the towel around it, and press — the towel absorbs the bulk of the water without stressing the knit.
5. Reshape immediately while still damp, then air dry flat on a clean surface. Never hang a wet wool hat — gravity will stretch it vertically out of shape as it dries.

Method 3 — Cleaning Felt Hats (Berets, Cloches, Structured Hats)

Felt hats are the most delicate to clean and the most commonly damaged by well-meaning attempts. A pressed wool felt hat — a 100% wool cloche or a structured felt beret — has been shaped under heat and pressure during manufacturing. The fibres are already partially felted by design. Introduce water incorrectly and you're accelerating a process that cannot be reversed.

The correct approach for felt hats is the brush-first method. A soft-bristled hat brush (natural horsehair is ideal) removes surface dust, lint, and light soiling without any moisture. Brush in a counter-clockwise direction following the nap of the felt — this is the direction the fibres naturally sit, and brushing with them keeps the surface smooth. For most wearing-related dirtiness, this is sufficient.

Steam Cleaning for Felt (When Brushing Isn't Enough)

Steam is the only safe deep-cleaning method for structured felt hats. It opens the fibre scales enough to release embedded dirt without soaking the hat or disrupting its shape. Hold the hat 6 inches from a kettle or clothes steamer. Move slowly and evenly across the surface — never hold in one spot for more than a few seconds or the felt will over-saturate. After steaming, use a clean damp cloth to blot the surface gently. Reshape while warm and allow to air dry fully before wearing or storing.

Method 4 — Cleaning Cashmere (Special Case)

Cashmere requires the gentlest handling of any hat material. The fibres are finer than merino wool — 14 to 16 microns in diameter — which is what makes them so soft, but also what makes them vulnerable to physical stress and harsh detergents. A cashmere beanie should be spot cleaned whenever possible and hand washed only when genuinely necessary. For a full breakdown of how cashmere, merino, and standard wool differ in construction and care requirements, the Complete Hat Materials Guide covers every fibre type in detail.

Use a dedicated cashmere wash or a very small amount of pH-neutral baby shampoo — never standard detergent. Soak briefly in cold water (maximum 20°C) for no more than 5 minutes. Any longer and the prolonged moisture exposure weakens the fibre. Press dry with a towel, reshape flat, and air dry away from all heat sources. A cashmere hat dried near a radiator or in direct sunlight will never feel the same again.

Between washes, cedar is cashmere's best friend. A small cedar block in your hat storage naturally repels moths (which are particularly attracted to fine animal fibres), absorbs excess moisture, and keeps the hat smelling fresh without any chemical intervention.

Stain Removal by Type

Drying Without Distorting

Drying is where most cleaning attempts fail. The washing itself was careful, the soap was appropriate — and then the hat went on a radiator for thirty minutes and lost its shape permanently. Wool dries slowly at room temperature, and that pace is not a problem. It's a feature. Fast heat-drying causes the fibres to contract and reset in whatever distorted position they happen to be in while warm. Once dry, that shape is locked.

The rules are simple: always air dry at room temperature, always reshape while still damp, and never hang a wet hat. For felt hats and berets, dry on a hat form or stuffed with tissue paper so the crown holds its shape as the fibres cool. For knit beanies, dry flat on a clean towel — laying it on its side creates an oval instead of a circle. For structured hats with brims, use clips or lightweight books to maintain the brim curve while drying.

Odour Removal Without Washing

Wool's natural lanolin is antibacterial, which is why a quality wool hat resists odour far better than cotton or synthetic alternatives. But sustained wear without airing — especially in warm conditions — will eventually allow odour-causing bacteria to accumulate in the sweatband. The good news is that most odour can be addressed without washing at all.

The most effective odour treatment is fresh air. Leave the hat in a well-ventilated spot — outdoors in shade, or near an open window — for 24 to 48 hours. The same antimicrobial properties that resist odour buildup also accelerate its dispersal. This handles the majority of between-season mustiness and general wear odour.

For persistent odour, place the hat upside down and fill the crown with a thin layer of baking soda. Leave overnight — the baking soda absorbs the odour compounds rather than masking them. Brush out thoroughly in the morning with a soft brush before wearing. A cedar block kept inside the hat during storage provides ongoing odour prevention and moth protection simultaneously.

Storage That Prevents the Next Clean

How you store a wool hat determines how often you need to clean it. A hat stored correctly — in a cool, dry, dark space with its shape supported — can go seasons between deep cleans. A hat thrown in a drawer or stacked under other items will need attention far sooner.

If you're investing in quality wool hats and want to avoid the sizing issue entirely — a hat that fits perfectly from day one never needs to be stretched back after an accidental wash — the Hat Sizing Guide explains how to measure and find a hat built to your exact head circumference. And if your hat has already shrunk and you need to recover it, How to Stretch a Wool Hat — And Unshrink One Too covers every method in detail.

Frequently Asked Questions