Placed on the edge of the door, “Keep door closed” shows only when the door is open, and hides when the door is closed. People need to be told “keep door closed” only when the door is open. The idea that the sign on this door shows only when it is needed and disappears from plain sight when it is not, is delightful. The sign is hidden until useful.


A similar application of “hidden until useful” is described by Apple’s Jonathan Ives as he talks about the sleep indicator light on the MacBook. He says, “It’s really important in a product to have a sense of a hierarchy of what’s important and what’s not important by removing those things that are all vying for your attention. An indicator has a value when it is indicating something. But if its not indicating something, it shouldn’t be there.”
(from Objectified)


The sleep indicator light on the MacBook disappears when it is not in use. The light emits through laser drilled perforations in the aluminum body. These holes are so tiny that the aluminum appears seamless when the light is off. Unlike other laptops that have a row of lights lining the front edge of the device, the sleep indicator on the MacBook does not even seem to exist until the computer is asleep. It kept hidden until useful.


Developing an hierarchy of what’s important and what’s not important, showing an indicator when it has value and keeping it hidden when its not, is much easier with electronic applications or virtual interfaces. It just needs to be programmed or wired. But what interests me are non-electronic applications such as the “keep door closed” example described above. It uses the physicality of the door or affordance of the door to hide and show the sign.


I decided to find more examples of “hidden until useful” in non-electronic applications and experiment with it on my own. One example I came up with is concerning dishwashers. A familiar problem with dishwashers is that it is hard to tell if the dishes neatly lined inside are clean or are in fact dirty.


Upon observation, I noticed that between closing the dishwasher full of dirty dishes and opening it to clean dishes, one of the things that changes is the cup that holds the detergent. Before the dishwasher is run, the cup is closed and after, the cup is flipped open. So I told my family, right after they empty the dishwasher, to fill it with detergent and close the cup. The closed cup indicates a dirty load, and therefore after the dishwasher runs and the cup automatically opens, we know that the open cup indicates that the current load of dishes is clean. Surprisingly this method is working for us. No more putting dirty dishes into a clean load so far.