3D-printed toilet is so slippery that nothing can leave a mark

A 3D-printed toilet is so slippery that almost nothing can stick to it, even after heavy use, meaning it could massively reduce the amount of water used for flushing.

There are many kinds of slippery toilet surfaces, like Teflon-coated bowls, but they all suffer from a lack of durability. The more they are used, the less slippery they become, so the coating or toilet needs to be replaced for it to remain effective.

Now, Yike Li at Huazhong University of Science and Technology in Wuhan, China, and his colleagues have developed a toilet that is extremely slippery and remains so in the face of abrasion.

Li and his team made a model of the toilet, around 10 times smaller than a full-sized version, by 3D printing a mixture of plastic and hydrophobic sand grains, using a laser to fuse the particles together and create a complex structure. They then lubricated the surface with a kind of silicon oil, which also penetrated below the surface because of the toilet’s material structure.

The researchers tested the toilet by throwing muddy water, milk, yogurt, honey, starch-filled gel and synthetic faeces into it, and found that none of them stuck. In fact, the toilet was just as slippery even after rubbing it with sandpaper more than 1000 times, which is a result of the lubricant oil sitting below the rubbed-away surface, says Li.

The toilet would be most useful in settings with a lot of use, such as on trains and in public bathrooms. “The reduced flushing volume would result in less wasted water during transportation to the processing facilities, thereby saving transportation costs,” says Li. But first the process needs to be adapted for full-size toilets and made cheaper, he says.

While the toilet seems durable and the lubricant used is environmentally friendly, it might be difficult to incorporate the laser manufacturing technique into current toilet production processes, says William Wong at Aalto University in Finland. “Nonetheless, I reckon if the motivation is sufficiently strong, it could be performed by a start-up company instead, which often tends to have flexibility in redesigning their supply chains,” he says.