Waterlight Graffiti is a material composed of several thousand LEDs that illuminate when in contact with water. By touching the edges of a LED, the water creates an electrical bridge that allows the LED to light up. The more water there is, the brighter the LED shines. Resulting from an idea as simple as it’s brilliant, the goal of Waterlight Graffiti is to propose a new reactive material to draw or write ephemeral luminous messages in urban space. Waterlight Graffiti is the result of the discovery of « dishu » during a trip to China. This practice consists in painting on the ground with water calligraphies of ancient texts and poems. By dint of seeing luminous billboards in the street that imprint our retina, Antonin Fourneau has imagined a new kind of interactive surface offering the public an alternative to the sad urban billboard and a new interaction in the public space. This creation is also a tribute to the « Etch a sketch » of the French inventor André Cassagnes who, through his invention, had also proposed a new surface of expression.