A plastic embedded with nanoparticles repels sludgy shampoo, so that every last drop slides easily out of the bottle. The nanoparticles are made out of cheap silica – a component of sand – so the new material could be mass produced. Decreasing the amount of shampoo wasted would save a lot of resources, says Sushant Anand at the University of Illinois in Chicago. A percent or two of product is lost in each bottle. “If you think about just a single bottle, it would seem not a big deal,” he says. “But if you think about billions of bottles, then it all adds up and it can make a huge difference.”