How it works

The short version: the print is designed to change colour when it gets warm and change back when it cools - temperature-reactive by design. Here's the honest detail.

Thermochromic ink

The prints use thermochromic ink: tiny capsules of pigment that change colour at a set temperature. We're aiming for ink that starts changing at around 31°C - roughly the temperature of warm skin. When the print cools below that, the colour comes back.

What sets it off

• Body heat where the fabric sits close to your skin
• A warm hand pressed on the print
• Warm rooms, radiators, hot weather or strong sun

Because it reacts to the temperature of the print itself, results vary. A loose hoodie on a cold beach may barely change; a tee on a hot day will change more.

What it doesn't do

• It doesn't detect mood, emotion or stress.
• It doesn't measure heart rate, effort or fitness - even where a design uses a pulse-line graphic.
• It isn't a thermometer, or a medical or safety device. Don't use it to judge sun exposure or body temperature.
• It doesn't cool you down, keep you warm or improve performance.

How the colour changes

Our visuals show blue turning red. In practice, most heat-reactive inks go from a colour to clear (or lighter) when warm, revealing a colour printed underneath - so "blue to red" usually means blue heat-reactive ink over a red base. On dark fabrics a light base layer is printed first. The final look is being decided in sampling, and we'll replace these visuals with photos and video of real garments before anything goes on sale.

It doesn't last for ever

Thermochromic ink gradually loses its effect with sunlight (UV), hot washes, tumble drying, harsh detergent, ironing and sweat. That matters for a beach brand: leaving it in strong sun will fade it faster. Looking after it makes a big difference - see care & testing.