Over the past three years, the fashion industry has started paying attention to biodegradable and renewable fabrics. Last year, Salvatore Ferragamo used a citrus byproduct material that feels like silk for a collection of shirts, dresses and pants; Philippines-based AnanasAnam created a faux-leather out of pineapple leaves dubbed Piñatex; and Dutch textile designer Aniela Hoitink created a mycelium dress that was as stylish as any satin cocktail dress.
Yes, mycelium—the interlocking root system that spawns forests of mushrooms in your yard after it rains. And this fungi fashion seems to be a trend: Microsoft’s Artist-in-Residence Erin Smith grew her own wedding dress out of tree mulch and mycelium; lighting designer Danielle Trofe uses mycelium to create biodegradable light fixtures; and Life Materials sells sheets of its mycelium leather for anyone interested in a do-it-yourself creation.
According to Silverman, the end result is a compostable, biodegradable mushroom-based sole that could replace rubber and other manmade components. But if it’s a compostable material, what happens if you wear the shoe in the rain?
John Taylor, professor of plant and microbial biology at the University of California at Berkeley, believes that unless the shoe sole is treated to prevent water intrusion, it’s far from ready to wear.
“There is likely a trade-off in durability versus compostability,” says Taylor, who isn’t involved in Silverman’s project. “Mycelium would absorb water if untreated, leading to degradation of shoe soles but promoting compostability. If the mycelium is treated to prevent absorption of water, the shoe sole function would be improved, but the compostability would decline.”
Silverman says that compostable products cannot compost without the correct conditions and organisms, so the soles shouldn’t just biodegrade during use. “Mycelium is naturally water-resistant so we believe if we let it grow to fully cover the substrate materials that the shoes would be able to tolerate at least some moisture,” says Silverman, though she does admit that “we do have some concerns about the flexibility of the material.”
While Silverman’s product may need some fine-tuning before it is market-ready, a California-based materials innovation startup called Bolt Threads is already accepting pre-orders for its mushroom “leather” bag in June. The company is known for creating its Microsilk fabric by copying spider silk gene technology. Through a new partnership with Ecovative Design, a company that created mycelium-based packaging and industrial-based materials, Bolt Threads Co-Founder Dan Widmaier is excited about the possibilities of renewable, sustainable fabrics, especially one that has the ability to replace leather and possibly lessen leather’s carbon footprint.