Two weeks ago, this new shoe was three plastic water bottles. After ground-up bottles are turned into recycled filament fiber and delivered to a factory, a San Francisco-based startup uses a proprietary process to 3D-knit the fiber into a seamless, essentially waste-free shoe. The knitting process takes just six minutes.
Rothy's, the startup making the shoe, wanted to make better footwear than they saw on the market. But as they tried to figure out how to also make the shoe more sustainable, they realized that they could dramatically reduce the materials that are normally thrown out in construction.
"You have a tremendous amount of scrap waste that's going into landfills," says Roth Martin, cofounder and chief creative officer of the startup. "Our process allows us to knit three-dimensional parts that use the exact amount of material that they need to use in order to create the part. So, like an inkjet printer, it draws just the amount of ink that it needs to complete that task, and then it repeats the task as needed."
It's a little like the method used to make some athletic shoes, such as Nike's Flyknit line (when the designers started work on Rothy's, Flyknit shoes weren't on the market). But it goes a step further: While Nike's shoes are knit in two-dimensions, Rothy's are "knit to shape" in three dimensions and come out of the machine fully formed. That helps reduce waste even more; the shoe snugly fits a foot without rivets and shoelaces, or buckles, or any extra parts.
In total, the shoe only uses three materials. The upper is made entirely from recycled water bottle filament, as is the insole, which is attached to a recyclable foam. (The material feels like fabric, not a plastic bottle). The sole is made from rubber.
"Traditionally in shoemaking, there's a tremendous amount of overproduction, because with footwear you have so many sizes and so many styles that it's very hard to gauge when buying and ordering materials for demand," he says.
The seamless shoe is also designed to be more comfortable. "There's no elastic in it, and no seams," says Roth. "So your foot's in contact with one material, which is novel in itself. And because of the knit structure, it has a nice give to it that holds its shape beautifully."
Eventually, the process could be used to knit shoes on demand. "That would mean you're only creating product when you sell product, rather than creating product in advance of demand," he says. "We think that the future is really a demand-driven generation rather than the traditional cycle, which exists in both fashion and footwear—and which is producing with long lead times, well in advance of seasons, and this constant fast-fashion cycle of replacement."
The designers spent eight months trying to build a supply chain in the United States, though that process ultimately didn't work. At their factory in China, they plan to soon add solar panels and keep pushing their sustainability performance even further.
They also plan to keep adding new shoes—and now that the basic process works, that will be easy. "It's really the equivalent of moving pixels around and just changing code slightly," says Roth.
The shoes are available on Rothy's website.