Science Man Explains Water-proof Water

Fumed silica is made of microscopic droplets of silica fused into chains. Its low density and high surface area makes it a thickening agent, but it has a lot of uses. It's used in toothpaste, cat litter and as a viscosity adjuster for paint, adhesives and other tons of other stuff. At least that's what we got from a cursory glance at Wikipedia. The more wow/science/fun/cool aspect of it is that it can make water hydrophobic.