You can squeeze as hard as you like, but those last stubborn drops of ketchup, shampoo or honey are practically impossible to retrieve from a near-empty bottle. Advanced nonstick coatings are threatening to put an end to this unavoidable wastage, and a new coating developed at Colorado State University is shaping up as a high-potential candidate. Made from edible wax, the coating has shown an impressive ability to shrug off sticky liquids like syrup to leave a receptacle bone-dry.

A lot of today's nonstick coatings rely on fluorocarbon chemicals for their water-resistant properties. This includes not just food packaging, but outdoor apparel and even high-performance fishing lines. The trouble is, fluorocarbons can decompose into perfluorooctanoic acid, which is toxic to humans and remains in the environment and body for a long time.

This has led scientists to look for safer alternatives. Hydrophobic, or water-repelling, surfaces inspired by the lotus leaf and spiders are just a couple of examples of progress being made in this area, and now the Colorado team have come across another natural source of inspiration for a greener kind of nonstick coating.

The team decided to try and make a hydrophobic coating out of beeswax, which it says has similar chemical properties to fluorocarbons but is non-toxic, and carnauba wax, or palm wax. The researchers were able to create their new nonstick coating by first dissolving the wax and then spraying it onto the surface to investigate its performance in food packaging.

After applying the coating to standard polystyrene cups, the team put it to the test with a range of substances, including Lipton green tea, Gatorade, pancake syrup, chocolate syrup and Coca-Cola. The coating proved effective at shunning the liquids when the vessel is turned upside down, with every last drop flowing out relatively quickly compared to the regular polystyrene cup.

The team is now working to improve the mechanical durability of the coating, which it says is not able to withstand harsh and abrasive environments. The coating can be seen at work in the video below, and a longer version using numerous liquids can be viewed via the source link.