How to Wash a Cap Without Losing Its Shape or Size

When nothing has fitted you for years and you finally hold a cap that genuinely does, the first wash is a nervous moment. I know the feeling well — I spent years looking for a hat that fitted my head, and that is exactly why this brand exists.

Most damage does not come from dirt. It comes from hot water, tumble dryers and rough handling. Above 60 cm, every lost centimetre shows up immediately: the cap starts pressing above your ears and leaves a red line across your forehead when you take it off. This guide is about getting your cap clean while keeping the exact shape and size you bought it for.

Why Caps Shrink and Lose Their Shape

Cotton fibres contract at high temperatures. It is not the water itself, but the combination of heat and mechanical movement — something a sixty-degree wash plus a tumble dryer delivers perfectly. At a standard size, nobody notices. When you wear 61 or 63 cm, you feel even a few millimetres.

The second issue is shape. The crown holds its form thanks to seams and structure, and violent tumbling pulls it sideways. A high-speed spin creases it into folds that then set as it dries, and the brim gets bent in directions it was never meant to go.

The third problem is the one people underestimate: sweat. Salt from your skin settles into the sweatband and over time draws white edges around it. The longer you leave them, the harder they are to remove — and the more aggressively you end up scrubbing.

So the most delicate part is not the fabric. It is the seams, the inner band and the brim structure. Spare those, and the material itself will last for years. This article is the short version for caps; the full guide by material, including stains and storage, lives on the caring for caps and beanies page.

Know Your Material Before You Reach for Water

Organic cotton is the most forgiving. Our baseball caps, dad hats and snapbacks are all 100% organic cotton — the beige baseball cap, for example. It handles lukewarm water and a mild detergent, and it shrinks mainly from heat, so as long as you stay under 30 °C and skip the dryer, there is nothing to worry about.

Merino is a different story. Wool airs itself out, holds no odours and needs washing far less often than cotton — with regular airing, once or twice a season is usually enough. When a wash is genuinely due, it belongs strictly on a wool cycle or in the sink, always with wool detergent. That applies to every one of our merino winter beanies.

Polyester blends, like a mesh trucker, hold up best. They keep their colour and dry quickly. But they dislike heat just as much: polyester can be shaped by heat, so whatever creases in hot water stays creased.

Before you reach for water, read the label and look inside the brim. Plenty of older or cheaper caps have a cardboard insert in there — it softens in water and ripples permanently. Whatever the insert is made of, one rule holds: brim shape is destroyed by heat, not by water. And a deeper crown with a wider inner band built for 61 cm means the shape returns more easily after a lukewarm wash than it would on a close-fitting cut.

Hand Washing, Step by Step

It sounds like effort, but it takes ten minutes of actual work. Fill a sink or basin with lukewarm water up to 30 °C and stir in a spoonful of mild detergent. Submerge the cap completely and leave it alone for a while.

Soaking does more work than scrubbing. Twenty to thirty minutes in the water loosens sweat and hair oils without you pressing on the fabric at all. Only then take a soft brush — an old toothbrush is ideal — and work gently along the sweat line and any visible stains. Go around embroidery; threads wear down faster than woven fabric.

• Never scrub dry fabric, only fabric that is fully soaked.
• Brush in one direction, not in circles.
• Rinse in clean lukewarm water until it stops foaming.
• Press the water out with your palms between two towels — never wring or twist.

For those white salt marks around the band, only one thing works reliably: dab a little enzyme detergent directly onto the edge, let it sit for fifteen minutes, then hand wash in lukewarm water up to 30 °C. Enzymes break down the proteins in sweat that soap alone cannot touch. Never put hot water anywhere near them — sweat is largely protein, and heat sets it permanently into the fibre. And enzyme detergent has no place on merino at all, because wool is a protein too; that gets washed with wool detergent and nothing else.

Skip bleach entirely. It eats through fibres and leaves marks on coloured models that nothing will undo. Fabric softener depends on the material: it does not belong on wool, because it coats the fibre with a layer that hurts moisture management, and wool detergents contain a softening agent anyway. On a cotton cap it is simply pointless. On an acrylic winter beanie, on the other hand, a small amount helps against static.

The Washing Machine: Why Hand Washing Is the Safe Bet

With structured caps — baseball caps, snapbacks and truckers — the best advice is to keep them out of the drum altogether. The drum throws them against the wall, and that is exactly what deforms the brim and the front panels, even at a low temperature. Hand washing in lukewarm water is always safer, and it takes ten minutes.

If there is no other way: a plastic cap cage, a delicate or hand-wash cycle, 30 °C maximum, a washing gel without bleach, and the spin switched off or set to minimum. Wash the cap on its own, not with the rest of your laundry — jeans and zips will hammer it for the whole cycle. Our dark grey trucker dries quickly on its own thanks to the mesh, but mesh creases easily in the drum and those folds stay in.

An acrylic winter beanie handles a delicate 30 °C cycle without trouble — just put it in a laundry bag so it does not rub against zips and buttons. Only put merino in the drum if your machine has a genuine wool cycle, meaning cold and with minimal movement, and you have wool detergent. Otherwise, by hand.

The tumble dryer is the one thing that will ruin a cap reliably. Hot air and tumbling together shrink the circumference and deform the crown within a single cycle. The popular dishwasher trick is much the same: tablets contain bleaching agents that are harsher on coloured cotton and embroidery threads than washing gel, and the drying phase runs at a temperature you would never otherwise expose a cap to.

Drying That Keeps Your Size

Always dry in the air and in the shade. Radiators, hairdryers and direct sunlight have no business near a cap. Heat finishes the job you avoided in the machine, and sun pulls the colour out on top of that.

The most important step is shaping the crown while the fabric is still wet. The best form is a rolled towel wound to exactly your head size. The household substitutes usually recommended — bowls, mugs, coffee tins, boxes — are built for a head of around 57 cm and would pull an XL cap inwards instead. A towel you can roll to 61 or 63 cm, whichever is yours. If you are not sure what you measure, have a look at the size guide. Measure about a centimetre above your ears across the widest part of your forehead, twice in a row, and take the larger number.

Straighten or curve the brim depending on how you wear it. It will dry in exactly the position you leave it in, so use that moment to your advantage. Dry winter beanies flat on a towel, spread back into their original shape — a wet beanie hung up will stretch under its own weight, and with wool that is permanent.

Let it dry completely, sweatband included. Damp trapped inside the band is the most common reason a cap starts to smell after a few washes. Allow 12 to 24 hours; the inner rim takes longest.

Once dry, check the fit. One finger should slide comfortably between your forehead and the cap, and there should be no red line when you take it off. If it is a touch tighter than before, fine-tune it with the buckle or the snapback — that adjuster is there for a reason.

Everyday Care That Means Washing Less

The best wash is the one you never have to do. After wearing your cap, leave it out in the open air for an hour, ideally turned inside up. That solves most of what sends people to the washing machine in the first place.

Store it on a shelf or a hook, not crushed at the bottom of a backpack. The crown keeps its shape by having room to hold it, and three days pressed flat under a laptop does more damage than a month of wear.

Rotation helps more than anything else. Two or three caps you alternate between will last many times longer together than one worn every day, because each one gets time to dry out and breathe. That is why our collection for large heads keeps colours you can wear every day and that work alongside each other.

Deal with stains straight away and locally. A drop of mild detergent, lukewarm water and a soft cloth will handle a fresh stain in a minute, whereas a week later it means washing the whole cap. For wool and merino models, get yourself a fabric brush — it keeps the surface clean without a single drop of water.

When Something Goes Wrong

Heat shrinkage is largely irreversible. No home remedy will reliably give you those centimetres back, which is exactly why lukewarm water and air drying matter so much at this size. A cap that has loosened with wear is a different matter: after a lukewarm wash and drying it pulls back to its original shape and feels tighter. That is not shrinkage, that is a return.

The prevention that works better than any repair: if you are unsure about the size, do not wash anything. An unworn, unwashed cap can be returned within 14 days; a washed one cannot. Try it first, and only then put it in water.

A deformed brim can be straightened with a damp cloth and patience. Dampen it, hold it in the position you want for a while, and repeat the process several times. Small steps get you there; force will simply break the insert, and then it is done for.

If your piece arrives damaged, do not sort it out on your own. Write to info@headofwonder.com with a photo and your order number, and we will send you a new one free of charge. You do not need to return the damaged one.

No compromises. A cap that finally fits you should last for years, not one season. If you are unsure about a particular stain or material, ask before you reach for the water rather than after.

The world is full of wonder, and one of its small wonders is the moment when, after years, something finally fits your head. Head size should never limit your choices, and proper care is simply a way to make that moment last as long as possible.

The complete guide by material — cotton, mesh, acrylic and merino, covering washing, stains and storage between seasons — is on the cap and beanie care page. If you are looking for another piece for the rotation, have a look at our XL caps for 60 to 65 cm. And if you are unsure about a material or a size, write to me at info@headofwonder.com. I answer personally and I will advise you based on what you have measured.