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  • Writer's pictureWorld Half Full

Toilets get slippery makeover


A slippery new coating could make the crappiest place in your home a little cleaner. Developed by researchers at Penn State University, this two-part product promises to keep the toilet bowl clean, odour-free, and — potentially — save a lot of water.

Worldwide, about 170 billion litres of fresh water are flushed down toilets every day, say the inventors of LESS or Liquid-Entrenched Smooth Surface, who published the results of their work in the journal Nature Sustainability. That’s because it takes a lot of water to flush away the bulk of our waste, which is because, as the authors put it, “human faeces is viscoelastic and sticky in nature, causing it to adhere to conventional surfaces.”

If toilet bowls were more slippery, less water would be needed to get the job done. That’s where LESS comes in. LESS consists of two sprayable coatings that can be applied to carbon steel, ceramics or other hard surfaces. The first spray dries into thin, hair-like structures so small they aren’t visible to the naked eye. The second is a lubricant that coats those ‘hairs’, making waste, water, and even bacteria slide off easily.

“Our coating can be applied by simply spray-coating or wiping directly onto the surface, and it is very easy to apply,” Tak Sing Wong, the lead author of the paper, told The Verge. “Household users can apply the coating themselves.”

The second coating is particularly important since disease-causing bacteria can thrive in human waste. Getting rid of those bacteria has a hidden benefit, too: it can reduce some of the smelly odours commonly found in bathrooms.

To test LESS, the researchers applied the coatings to glass and ceramic and then dripped and dropped dyed water and “synthetic fecal matter” onto the coated surface.

One of the qualities the researchers were looking for was durability. The first layer of LESS is permanently bonded to the surface, but the lubricant layer needs fairly frequent touch-ups to maintain its slippery nature. The researchers estimate the coating can last about 500 flushes. Wong estimates that, for a household of four, that might require reapplying the second layer about every two weeks. In a more commercial setting, it would have to be applied about every two to three days.

But what happens to the coating as it gets slowly flushed down into the sewer system and out into the world? Wong says the LESS coating contains silicone, which breaks down in soil into the relatively harmless substances silica, water, and carbon dioxide. The team hopes that if the coating is used widely, it could help reduce water use, especially in areas experiencing water shortages. And it might help keep waterless toilets — common in some parts of the world — cleaner.

Wong and his colleagues have formed Spot LESS Materials to get their product out of development and into our toilets. A coating kit for toilets is available on their website for US$20.

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