Some thrifty types cut open their bottles, while others just bin them – even though there is enough left for a thorough hair wash. But now researchers have solved the dilemma of squeezing the last drops of shampoo out of a bottle. They have created a lining that will allow soap to pour cleanly out of plastic containers, reducing waste and irritation. The lining is made up of microscopic y-shaped quartz structures which, apparently, create air pockets that stop the shampoo touching the side of the bottle. Inventors Bharat Bhushan and Philip Brown said the technique works on polypropylene, a common plastic used to package foodstuffs and household goods. Professor Bhushan said, “It’s what you would call a first world problem, right? ‘I cannot get all of the shampoo to come out of the bottle’. But manufacturers are really interested in this because they make billions of bottles that end up in the garbage with product still in them. Coatings already exist to help food, but not soap, pour out of their containers. Compared to soaps, getting ketchup out of a bottle is trivial. Our coating repels liquids in general, but getting it to repel soap was the hard part.” The shampoo bottle lining is said to be cheap, effective and environmentally friendly. The quartz structures are only a few micrometers – millionths of a metre – across, are as hard as glass and are covered in even tinier branchlike projections. This means the soap is unable to spread across the lining and instead forms into beads which roll across its surface. The invention could boost recycling as plastic bottles must currently be rinsed clean before they can be recycled. Professor Bhushan, whose team at Ohio State University announced their discovery in the Philosophical Transactions of the Royal Society, said, “We all struggle with shampoo bottles. I have a few in my shower right now. Trying to get the last drop out, I put it upside down.” He added, “My wife adds water to the bottle and she fights with it for a while, and then we give up and just throw it away.” The Ohio scientists are not the only ones working on a solution to the plastic bottle problem. Inventor Richard Fereday, 54, is appealing on the crowd-funding website Kickstarter for investors in his Flying Saucer, which promises to help diners empty their sauce bottles. The product works by placing a bottle, tube or jar in a cone-shaped holster. When the user swings the device in a windmill motion, centrifugal force draws the sauce into the gadget. The cap is taken from the pouch and used as a funnel to pour out the contents. The device also works for cosmetics such as hand cream. Richard Fereday, of Christchurch, Dorset, hopes to raise £8,000 to cover costs and then to sell the gadgets for £15.