A special phosphor colour was mixed with normal wall colour and applied to the hotel room walls with a mask. The result: As long as the room is well-lit, there is nothing. But as soon as the light is switched off, the ad becomes visible: Glowing text on the wall. A few moments later the ad fades and disappears again.

The sales volume of the bar increased by 34.7%. And: The idea underlined the up-to-date design image of the hotel.