The Firefly Jacket

The Firefly Jacket is a high performance, five-layered, 400 gram, waterproof and windproof shell built with two colour-shifting membranes. Normally we like to say what colour the piece of clothing you’re buying is. But with The Firefly Jacket that’s not so easy. With one of the membranes infused with a phosphorescent compound, and the other built with a fluorescent compound, the jacket changes colour throughout the day and night as the light conditions change around it – so it can be anything from copper, to orange, to glow-in-the-dark green, to a yellow that’s so trippy under UV light that you look like you’ve wandered off the set of Avatar.

Of course this kind of multi-layered luminescence has been found in nature long before we existed. Possums, sharks, frogs and flying squirrels have been flexing biofluorescent fur and skin for millions of years. But you won’t find it in clothes… until now. So this is the first chance for humans to get in on the action.

Just to build a jacket with just one colour-shifting membrane is really complex. You have to sandwich the ultra-thin membrane between two equally thin layers of mesh. Make the mesh too thick, and the membrane won’t be able to absorb or re-emit light. Make them too thin and the jacket will fall apart. So building a high performance jacket with two colour-shifting membranes has taken years of R&D, and requires 5 ultra-thin layers.

The Firefly Jacket is built from a single fabric made from 5 ultra-thin, alternating layers. Layers 1, 3 and 5 (the outer layer, middle layer and inner layer) are a translucent, polyamide mesh. Layers 2 and 4 are the two colour-shifting membranes – one phosphorescent, and the other fluorescent. The phosphorescent membrane lets the jacket glow in the dark at night. The fluorescent membrane reacts to both visible and invisible light to change the colour of the jacket during the day and night.

The second you turn the lights on, or the clouds clear, The Firefly Jacket turns orange. The fluorescent and phosphorescent membranes both absorb and re-emit UV light from the sun. So the brighter the sunlight, the brighter the orange.

Charge it up at night by lighting it up with your car headlights or a high-powered torch and it will glow green like kryptonite. And under a blacklight at night the jacket turns fluorescent yellow.

To see just how responsive the phosphorescent membrane is at night, the simplest thing to do is go into a dark room and start writing on it using the torch on your phone against the surface of the fabric as if you were using a pen on paper. It will start glowing instantly and leave a trail of light. There is no time lag or warming up. The fabric reacts the moment light strikes it. The wider the beam the thicker the line – so a high-powered torch will create the coolest effects.

Fluorescent and phosphorescent materials absorb high-energy UV light that the human eye can’t see, and re-emit it as low-energy light that it can see. The only difference between the two of them is how long that process takes. Fluorescent materials re-emit light instantly, so you need a constant source of UV light to see them. Phosphorescent materials re-emit light over time, giving them a glow-in-the-dark effect that can last for seconds, minutes, or hours after the light source is removed. Thanks to the two different membranes, The Firefly Jacket does both.