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This slippery new coating could make toilets less filthy

This slippery new coating could make toilets less filthy

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The sprayable coating could also help reduce wastewater

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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 your toilet bowl clean, stink-free, and — potentially — set the stage for toilets to use less water in the future.

Worldwide, about 37 billion gallons of fresh water are flushed down toilets every day, say the inventors of the new product who published the results of their work this week in the journal Nature Sustainability. The reason we send so much water down the drain? It takes a lot of water to get rid of the bulk of our waste. Or as the authors put it in the paper: “human faeces is viscoelastic and sticky in nature, causing it to adhere to conventional surfaces.”

“viscoelastic and sticky in nature”

If people could make toilets more slippery, less water would be needed to get the results of those bowel movements moving down the drain. That’s where the new liquid-entrenched smooth surface (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 that 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 in an email. “Household users can apply the coating by themselves.”

The latter is particularly important since disease-causing bacteria can thrive in human waste, which is why sanitation is such a high priority for public health advocates and experts. Getting rid of those bacteria has a hidden benefit, too: it can reduce some of the foul odors commonly associated with bathrooms. Other self-cleaning toilet ideas have focused on liquid cleaners or UV light to get rid of germs and stains.

To test LESS, the researchers applied the coatings to glass and ceramic and then dripped and dropped dyed water and “synthetic fecal matter” — a mix of seven ingredients, including yeast, peanut oil, and miso — onto the coated surface.

One of the things that the researchers were looking for was durability. The first layer of LESS is permanently bonded to the surface of whatever it gets applied to, but the lubricant layer needs fairly frequent touch-ups to maintain its slippery nature. The researchers estimate that the coating can last for about 500 flushes. Wong estimates that, for a family 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.

researchers estimate that the coating can last for about 500 flushes

But what happens to the coating as it gets slowly flushed down into the sewer system and out into the world? Wong says that 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. They also claim that it might help keep waterless toilets (common in some parts of the world) cleaner.

Wong and his colleagues have started a business called Spot LESS Materials to get the product out of development and into our toilets. A coating kit for toilets is available on the website for $20.