Almost any surface or fabric can be made waterproof but remain breathable thanks to a former military technology.
The process was originally developed to ensure soldiers’ clothing remained impermeable to chemical weapons.
Shoe maker Hi-Tec has signed a deal with the developers of the process to use the technology to waterproof many of its shoes.
The first commercially available shoes treated with the process were shown off in London this week.
The technology was funded by the Ministry of Defence and developed at its Defence Science and Technology Laboratory for making military clothing resistant to nerve agents.
The process – dubbed ion-mask by its inventors – works using a chemical based on the element fluorine. In a closed chamber, the chemical is vaporised and attaches, molecule by molecule, to all the fibres in a fabric.
The chemical makes the surface “hydrophobic” or water-repelling, so that instead of water spreading out it forms droplets on the surface.
The chemical coating covers just the fibres, rather than forming a “skin” across the whole surface, as with currently available waterproofing treatments. That means the spaces between fibres remain open and the fabric is still breathable.
“The normal way in which you’d make a shoe waterproof is put a membrane inside the shoe; Gore-Tex is a well-known example,” says Ian Robins, business development director of P2i, the company marketing the process.
“That’s effectively putting a plastic bag inside the shoe. No water gets inside your shoe, but at the same time that reduces the breathability both in terms of sweat and of heat escaping.”
Shoe fabric made with the ion-mask process was tested for breathability in an air-flow test, outperforming commercial waterproof fabrics such as Gore-Tex by more than a factor of 100, P2i claims.
The shoes were also subjected to flexing and wear tests, maintaining their breathable waterproof properties even after 100,000 flexes.
The fabrics are also inherently stain-resistant and easier to clean, says P2i.
Dr Robins says coating a pair of shoes using the ion-mask process requires just a tenth of a gram of the fluorine compound, and costs in the region of a few dollars – significantly less than the cost of integrating membranes like Gore-Tex into a pair of shoes.
The process can easily be applied to any garments or any material, and Dr Robins suggests that it might also become the basis for a separate after-purchase service business, like dry cleaning.
It can also be used to waterproof outdoor gear. High Street outdoor equipment retailer Millets, owned by Black’s Leisure Group, will be stocking the men’s Hi-Tec ion-mask shoes in 75 stores.
“This could change waterproof footwear as we know it,” says Michelle Swan, a senior footwear buyer at Black’s.
She said the company would keep an eye on the “revolutionary” technology and perhaps use it in other areas of its business.