A spray on treatment that makes any object repel liquid has been launched in the US. This is NeverWet, a superhydrophobic coating that can be applied to nearly any surface.
Consumers can now buy the two cans (capable of treating 10 to 15 square feet) for $19.97 from Home Depot. Surfaces that the spray can be applied to include fabrics, wood, metal and plastics. The treatement consists of two coatings, each of which takes 30 minutes to dry.
NeverWet have not yet given official figures on how long the superhydrophobia will last in various situations, but claim that treatments have “remained under seawater for over a year and reemerged completely dry.”
Unfortunately, when the treatment is applied to glass it causes the surface to become frosted, though the company behind the product promise that a clear-drying version is in development.
A demonstration video (below) shows NeverWet in action, including waterproofing an iPhone (something that instructions for NeverWet explicitly warns against), a toilet brush, a t-shirt and a pair of shoes.
Superhydrophobic surfaces work by increasing the contact angle between water droplets and the surface by creating a low surface chemistry – essentially changing whether each individual droplet remains a ball when it rests on a surface, or whether it spreads out.
Hydrophilic surfaces (surfaces that soak up water) have a contact angle of less than 90 degrees. Hydrophobic surfaces have a contact angle of above 90 degrees, but superhydrophobic surfaces have a contact angle of above 150 degrees.
NeverWet coatings creating a contact angle of between 160 and 175 degrees (by comparison, the non-stick coating on a Teflon pan is a 95 degrees contact angle).