Physics whizzes create 'black hole' to stop urinal splash-back

Aiming to keep khakis clean of urine droplets, a team of researchers turn to moss to develop an insert that will grab more pee.

Michael Franco
Freelancer Michael Franco writes about the serious and silly sides of science and technology for CNET and other pixel and paper pubs. He's kept his fingers on the keyboard while owning a B&B in Amish country, managing an eco-resort in the Caribbean, sweating in Singapore, and rehydrating (with beer, of course) in Prague. E-mail Michael.
Michael Franco
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Does moss hold the key to eliminating urinal splash back?

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As many a khaki-clad office worker knows, a perfectly clean pair of pants can suddenly become a speckled minefield from a single use of the urinal. Sometimes it seems urinals have a force field that actively repels fluid.

The problem: streams of urine break up and form tiny droplets as they leave the body. When those droplets strike the surface of a urinal, they can bounce back and turn a solid pair of pants into a polka-dotted one.

Now, a team of scientists working with Utah State University's Splash Lab believe they've come up with a way to solve the splash-back problem. Their solution is a urinal insert that's similar to a moisture-loving moss known as Syntrichia caninervis, which has a pillar-like design. The team presented their work last week at the 68th Annual Meeting of the American Physical Society's Division of Fluid Dynamics in Boston.

"With this natural splash suppressor in mind, we [searched] for the ideal urine black hole by performing experiments of simulated urine streams," the researchers said in their abstract. "We propose improved urinal insert designs based on our experimental data in hopes of reducing potential embarrassment inherent in wearing khakis."

The proposed insert would, just like the moss, have a "forest" of small, precisely arranged pillars. Gentlemen needing to relieve themselves would aim for the insert, and the perfectly placed and sized pillars would trap any liquid trying to leap out of the urinal.

While eliminating urinal splash back is certainly a lofty goal, the scientists hope their research will hold broader scientific appeal.

"While we find the connection to urinals interesting, we are confident that the scientific community will have interest in the interaction between the splashing droplet and the pillars," researchers Tadd Truscott and Randy Hurd told Gizmodo.

This isn't the first time the Splash Lab has tackled the problem. In 2013, using water shot through a 3D-printed artificial male urethra, the team recorded different angles and the resulting splash-back patterns using high-speed cameras. They concluded that standing as close as possible to the urinal and angling the urine stream downward would create the least amount of splash.

So guys, until black-hole urinal inserts are a real thing, it looks like that's your best bet (see video below in case it's not clear). The method even works with toilet bowls, but the difficulty factor goes up a lot.

"Although reducing the impact angle would also work in traditional toilets, these angles tend to only present themselves around the rim of the bowl, simultaneously increasing the chances of missing the bowl entirely," Hurd said at the time. "I wouldn't recommend this approach to anyone but military snipers."

Truscott told CNET's Crave blog he and his team are still evaluating the feasibility of producing and marketing the insert. Until then, they will likely publish their work and patent the concept.