Envisioned for an urban train station, Figment is a dynamic clock that appears and disappears on the surface of a large concrete wall. It was designed in response to the following prompt.

It was a warm summer’s day and the train station was bustling with travelers. As they scurried to and fro, some of them noticed a strange phenomenon: a large ghost clock that seemed to appear and disappear on the wall of the station.

At first, they thought it was just a trick of the light, but as the clock kept flickering in and out, they began to realize that something supernatural was afoot. People began to point and whisper, and a few of them even attempted to snap a selfie with the mysterious clock. But each time they tried, it would disappear before they could capture it.

The travelers were understandably frustrated, but none of them could explain the phenomenon. As the clock continued to come and go, speculation began to spread throughout the station. Some suggested that it was the ghost of a long-forgotten traveler, while others said it was the spirit of time itself, trying to remind people to not take life for granted.

No one could confirm any of the theories, and the ghost clock kept appearing and disappearing, leaving the travelers in awe and confusion. Despite the mystery, one thing was certain: the travelers would never forget the strange sight.

The effect of the ghost clock would be achieved by using a heat-sensitive thermochromic coating, which changes color in response to specific regions of the wall surface being warmed. Embedded electrical wires in the wall would provide this change in temperature at the surface.

When the wires become warm, the clock would appear because regions of the thermochromic coating near the wires would turn transparent, partially revealing a darker substrate that’s beneath the coating. The clock would fade away when the wires cool, because the thermochromic coating would to turn from transparent to opaque, thus hiding the dark substrate and causing the clock to disappear.

One of the more lovely effects of this phantom clock will be its unhurried emergence and disappearance, because it would take time for the wall to locally warm up and cool down. The color change would not be fast enough to elude selfies. Still, it would be magical, as the transformation would be achieved in the material of the wall itself. It is not a projection or a screen, as you can see in the video, above, which includes an inverted black-on-white demonstration prototype.