Ladies and gentlemen, it’s time to say goodbye to privacy in the place where it mattered most – the restroom. A wacky cafe in Vienna has installed see-through toilet doors that only turn opaque if the users lock them.

For a lot of people, using the toilet in public places is uncomfortable enough, but the owners of Cafe Diglas, in Vienna, Austria, decided to make it even worse for them by replacing the regular bathroom doors with transparent glass ones that allow anyone who walks in to literally catch them with their pants down. Luckily, it’s not really as bad as it sounds. You see, these are smart toilet doors that turn opaque at the turn of a switch. All the user has to do is lock the door when they’re inside and watch the see-through glass become opaque as a light above them projects a no-entry sign onto it. It’s a really cool trick, but the viral YouTube video that shows them in action doesn’t come with an explanation of the magic that makes them switch in an instant.

Photo: Catherine Motuz

Luckily some of the video comments shed some light on this neat technology:  “It’s actually really simple. It’s to do with the glass being made of silver halide molecules that align allowing light to pass through, when the voltage is removed it the molecules randomise absorbing more light making the glass translucent,” a YouTube user writes. He is quickly contradicted by another who claims “it’s the other way around, once the voltage is added it becomes translucent, turning the lock completes the circuit and provides the atoms with energy making them vibrate, thus being translucent.” I’m hoping the second version is the right one, otherwise a power-out could put Cafe Diglas patrons in a very embarrassing situation.

Photo: Catherine Motuz