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WATCH: Here's What Happens When Hydrophobic Sand Is Dropped in Water

FIONA MACDONALD
9 FEB 2015

The material in the video above looks like normal sand and, as far as we can tell, feels like regular sand. But it sure doesn't act like it, as you can see in this episode of BBC's iconic quiz show QI, from 2012.

 

The experiment starts out normally enough, with host Stephen Fry sprinkling some red sand into a glass of water, where it forms a thin, floating layer. But then he shoves his finger into the water and instead of going right through the sand, the grains form a barrier for his skin and he emerges completely dry. 

So far, so strange. But things get really bizarre when he adds a whole heap of blue sand, and it forms a congealed, alien-looking structure submerged at the bottom of the glass. When he scoops some of it out with a spoon? It comes out completely dry and untouched.

We're with the contestants on this one, it's pretty much witchcraft. Except it's even better, because it's science.

The experiment is also surprisingly simple to replicate at home. All you need is some sand and some water-repellant spray, such as Scotchgard (or gotchscard, which you'll understand when you see the clip above). You spread the sand out and then give it a couple of genorous coatings of water-repellant chemicals. Once it's dry, you're now the proud owner of hydrophobic sand. 

You can also even buy hydrophobic sand, called Magic Sand, that's pre-made, and contains ordinary beach sand mixed with tiny particles of silica. The combination is then exposed to vapours of trimethylsilanol, an organosilicon compound, that bonds to the silica particles, creating a hydrophobic coating for the sand.

Both Magic Sand and the DIY hydrophobic variety will do anything it can to avoid contact with liquid, including forming strange formations underwater to reduce surface area.

But if you think that's cool, wait until you see kinetic sand, which is sand mixed with Silly Putty that's forever wet. 

And scientists have now also used lasers instead of chemicals to etch this super-hydrophobic metal - it's so hydrophobic, in fact, that water just bounces right off it like magic.

Stephen Fry would be impressed.

Source: BBC