Working up a sweat - understanding how sweat forms, spreads, and evaporates on our skin

Embargoed until: Publicly released: 2025-07-23 09:01

International

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Sweating helps us stay cool in hot weather and affects how our skin interacts with clothing, cosmetics, and wearable technologies. To understand how sweat travels to, spreads on, and evaporates from skin, international researchers applied a suite of instruments and advanced imaging tools to observe sweating on the foreheads of six people wrapped in heated blankets as they warmed up, cooled off, and warmed up again. They found that during the first 15 minutes of sweating, sweat forms in pores and evaporates. Beyond this, the upper skin reaches 'hydration’ and the sweat puddles spread from the pores like a film. Salt on the skin from past sweat cycles made the spread quicker; and even the most hairless forehead has fine hairs that may make sweat evaporate quicker.