Wash a baseball cap without losing its shape: the gentle method

Your favourite cap has been with you all summer: cycling, at the lake, on hikes. Now the sweatband shows a yellow ring, and sunscreen and dust are stuck to the brim. When you set out to wash a baseball cap, one fear dominates: that it will come out dented or with a warped brim.

With the right method, the shape stays intact. What matters is the material of the brim, lukewarm water and drying the cap on a form. Five steps show how to gently clean baseball caps, trucker caps and wool caps.

Why a baseball cap gets dirty so quickly

A cap sits directly on your forehead and hair. The sweatband absorbs sweat, skin oil, hair products and sunscreen. Over time, yellowish marks and white salt crusts appear, and the cap starts to smell. On the outside, dust, pollen and splashes build up.

At the same time, a cap is more delicate than it looks. The brim, the front panels and sometimes a stiffened front give it its shape. Cleaned the wrong way, the brim bends, the front goes wavy or colours run. So it pays to take a close look before you start.

1. Check the label and the brim

First look at the care label, usually inside on the sweatband. A hand in the wash tub means hand wash only. According to the GINETEX care symbols index, that means 40 °C at most or 20 to 30 °C, depending on the symbol, without rubbing or wringing. A crossed-out tub means: do not wash in water.

As for the brim, newer caps almost always have a plastic insert, while older or cheap models sometimes contain cardboard. Tap the brim with a fingernail and bend it slightly. If it sounds dull and feels soft or papery, there is probably cardboard inside. A cap like that must never be soaked: the cardboard swells and loses its shape for good. In that case, only spot-clean it with a damp cloth.

2. Prepare and test the colours

Brush off dust and hair with a dry, soft brush. Remove pins and detachable parts. Then test for colourfastness: press a damp white cloth against a hidden spot on the inside. If colour comes off, wash only in cold water, briefly and separately.

Sunscreen marks on the brim come off with a little delicates detergent on a damp cloth. For more on this type of stain, see our guide to removing sunscreen stains.

3. Wash a baseball cap by hand

1. Fill a sink or bowl with lukewarm water and dissolve a little delicates detergent in it.
2. Rub the sweatband with gall soap or a paste of bicarbonate of soda and a little water, and leave it for a few minutes.
3. Gently brush the band and seams with a soft toothbrush, always along the grain of the fabric.
4. With a plastic brim, briefly dip the whole cap and clean the outside with a brush or sponge; with a cardboard brim, only dab the fabric parts.
5. Rinse thoroughly with clean, lukewarm water until no more foam comes out.
6. Gently press out the water without wringing, then blot with a towel.

The Swiss consumer protection foundation (Stiftung für Konsumentenschutz) lists curd soap, bicarbonate of soda and vinegar among the tried-and-tested household remedies that handle many cleaning jobs without special products. For stubborn sweat marks, gall soap also works well; see our guide on using gall soap.

4. Washing machine and dishwasher: what works

Some cotton or technical-fabric caps with a plastic brim can go in the machine according to the label. If so: delicates programme at 30 °C maximum, in a mesh bag or a special cap washer frame, together with a few towels and without spinning. EnergieSchweiz, the Swiss federal energy programme, recommends washing at low temperatures of 20 to 30 °C anyway – ideal for caps.

The dishwasher is often recommended as a trick, but it is not a good idea. Temperatures are usually above 30 °C, and dishwasher detergents are far harsher than delicates detergent and can bleach colours. In the top basket, the water jets distort the cap, and food residue from the filter ends up in the fabric. A cardboard brim won't survive it anyway.

5. Dry it in shape

After washing, a baseball cap dries best on a round form so that the crown doesn't collapse. A ball, an upturned bowl, a coffee tin or a rolled-up towel all work. Straighten the brim and crown by hand while the fabric is still damp.

Let it dry in an airy spot in the shade. No tumble dryer, no radiator and no blazing sun: heat warps the brim and sunlight fades colours. Depending on the material, drying takes from a few hours to a day.

Common mistakes when washing a baseball cap

• Soaking a cardboard brim: it swells and stays misshapen.
• Washing too hot: above 30 °C, colours can run and the fabric can shrink.
• Wringing: the crown creases and the front goes wavy.
• Drying it flat: the cap collapses and dries lopsided.

Priority Clean editorial teamOur cleaning team from Alberswil, Canton of Lucerne, shares hands-on experience from move-out, house, office and window cleaning across Central and Northwestern Switzerland.