what to wear in the sauna

the short version: natural fibres. linen, cotton, wool. they handle heat and sweat better than plastic does, and they don’t bring the chemistry of synthetic fabric into a room where your body is wide open. that’s most of the answer. the rest is detail.

why natural fibres suit the heat

a sauna is a demanding place for a fabric. it’s hot, it’s wet, and you’re pressed right up against whatever you’re wearing while you sweat. natural fibres are good at this. linen and cotton breathe and shed water fast. wool, as we’ve written elsewhere, insulates and holds moisture without melting or smelling. they’ve been worn in heat for thousands of years and they behave.

most modern swimwear and gym kit is the opposite. it’s polyester, nylon and elastane, which are plastics, and plastics weren’t designed with a 90°c room in mind. they trap heat against you, they can feel clammy once wet, and over time synthetic fabric sheds tiny plastic fibres, the microplastics that keep turning up everywhere researchers look. then there’s the colour and the finishing. a lot of synthetic fabric carries dyes and treatments you wouldn’t choose to sit and sweat in if you could read the label.

a quick word on heat and skin

there’s a reason the material matters more in a sauna than in a cold changing room. warm skin is more permeable than cool skin. heat raises your skin temperature and opens up the blood vessels near the surface, and a sweating body absorbs more readily than a dry one. it’s the same basic principle behind heat-assisted skin patches in medicine. nobody’s saying your swimsuit is dosing you with anything. the honest point is smaller and still worth making: the heat is exactly the moment to be a little choosier about the fabric on you.

what to wear, by sauna

in a public sauna, most places in the uk, europe and the us ask you to wear something. a natural-fibre swimsuit or pair of shorts is the move. look for linen, organic cotton or hemp, and ideally something coloured with plant or mineral dye rather than synthetic.

in a private or finnish-style sauna, the tradition is simple. nothing, with a towel to sit on, linen or cotton. add a wool hat to keep your head out of the worst of the heat, which we’ve a whole piece about.

what we’d skip

a short, honest list of things that don’t belong on a sauna bench. heavily dyed synthetic swimwear, because the colour and finish are the most likely to come off when hot and wet. anything with rubber, silicone or metal trim that gets hot enough to nip you. and “quick-dry” fabrics treated with pfas, the so-called forever chemicals, which stay on the fabric and don’t do you any favours.

none of this means plastic is evil in all things. it means the sauna, hot and wet and close, is a poor place for it.

where we come in

for now we make one thing for the heat: a wool sauna hat, natural fibre through and through. we’re working on more, made the same way. when it’s ready, the people on our list hear first.