In London, sustainable fashion pioneer Stella McCartney has unveiled a new version of its S-Wave sneakers, featuring soles made entirely from BioCir Flex, a castor-oil based bioplastic developed by materials startup Balena. Unlike traditional plastic soles, this plant-based material is fully compostable or recyclable, offering a sustainable alternative without sacrificing durability.
The soles are dyed using cinnamon waste, and the shoe uppers are crafted from hemp and agricultural byproducts from the pineapple industry. According to the company, the shoes even smell like cinnamon.
“The real hurdle was how to match the durability and flexibility of traditional fossil-based plastics . . . using a biobased material that could also break down at end of life,” says Yael Vantu, head of product at Balena. “That balance of true compostability without sacrificing performance simply hadn’t been cracked yet. Most biodegradable materials on the market just aren’t built to handle the stress, abrasion, and longevity needed in a sneaker sole. That’s where our material came in.”