Fantastic Fungi, Louie Schwartzberg

Scaling a Next-Gen Material

Words by Lauren Cochrane

The recent release of Stella McCartney’s Frayme bag, the first ever mushroom leather bag to be sold commercially, has been a long time coming. Its debut serves as a blueprint for brands entering an era of biomaterials in search of greener fabrics.

Stella McCartney recalls her first visit to Bolt Threads, the pioneering materials company, in 2016. “I remember touching this spider silk they presented to me during that first meeting, and I just couldn’t believe how soft and luxurious it was,” she says. “That’s where we began—first with the spider silk then they introduced us to Mylo.”


Six years later, and McCartney is launching a handbag made from the material—a version of what’s commonly referred to as “mushroom leather,” made from mycelium, the root-like structure of fungi. It’s an industry milestone as the Frayme is the first ever bag made from the material to be sold commercially. A limited edition, it will be followed by the use of Mylo throughout the brand’s collection from 2023.


The Mylo bag is the result of lots of back-and-forth between McCartney and Bolt Threads. “We had to ensure the bag we put to market was 100% ready for our customer and able to withstand our customer’s busy life,” says the designer, adding “the hardest, longest part was probably getting the material to a level that we were happy with and that would be viable as a bag that we could actually sell to our customers and not expect returns.”


Arguably, McCartney’s work is a blueprint—meaning more brands now know it’s possible to produce a commercial product with this experimental material, rather than bovine leather. Jamie Bainbridge, the Vice President of Product Development at Bolt Threads, says the designer “has paved the way for luxury brands who are looking to make products that are animal-free and made using environmentally conscious materials and practices.”


Bolt Threads also work with Lululemon and Ganni on their designs with four Mylo products in total now available to buy. This is just the start. “In the future, we hope to make Mylo material accessible to any designer or brand or industry, from apparel and accessories to automotive, to upholstery and beyond,” says Bainbridge.

“The great eras in human history are described by their material like the Stone Age and the Bronze Age. We are in the early days of the Biomaterials Age.”

Matt Scullin
CEO of MycoWorks

Matt Scullin, the CEO of MycoWorks—the other major mycelium-producing company—goes further. He sees the material as part of the latest historical era. “The great eras in human history are described by their material, from the Stone Age and the Bronze Age to the Iron Age,” he says. “We are in the early days of the Biomaterials Age.” MycoWorks’ mycelium product is called Reishi. It’s this which Hermès, a brand well-known for its leather, used to make their first mycelium product, a version of the Victoria shopper, last year.


If having luxury brands on side is a boost, a burgeoning industry—complete with two companies vying to be top dog—is also proof of the viability of mycelium going forward. In January 2022, MycoWorks announced they had raised $125m in their latest funding round, with a new full-scale production facility planned in South Carolina, while Bolt Threads was valued at $10 billion in September 2021.


Gemma Curtin is a freelance curator who worked on the materials-based Waste Age exhibition at London’s Design Museum in 2021. She says the key to mycelium gaining ground is to not see it as a like-for-like replacement for leather. “It will probably have some of the same elements of leather, and it may be that it can replace it in certain situations, but not others,” she says.


It is certainly tempting to try to adapt it to as many uses as possible. If leather is both 15% of the luxury goods market and part of the animal agriculture that contributes 18% to the world’s greenhouse gas emissions, mycelium uses little space, energy or water, and it is biodegradable. But while it is quick to grow—a tray of fungi can produce a hide of leather in a matter of weeks—and can be grown to order, it remains expensive to produce, with Bolt Threads’ Mylo currently $25 per square foot. This limits its current use to brands that sell goods for higher price points, particularly because many brands at the lower end of the market use cheaper synthetic leather alternatives rather than leather itself.


This price issue is born out in McCartney’s design—the Mylo Frayme bag is around 25% more expensive than others in the same range. But she hopes this is a temporary state of affairs: “the more in demand this material becomes and the more production ramps up, the cheaper it will become for everyone, making the possibility of replacing real leather a reality.”

“The more in demand this material becomes and the more production ramps up, the cheaper it will become for everyone.”

Stella McCartney

Beyond price, Mylo still has some issues in its current state. It can only currently be produced in black, and McCartney says part of the development for the Frayme bag was finding an alternative glue because the vegan one the brand typically uses wasn’t sticking. But, with different colors and textures in her sights, McCartney is enjoying a moment where materials have finally caught up with her vision of vegan luxury—one she has been working on since founding her brand in 2001. “It’s an incredibly exciting time to be working in fashion,” she says. “It feels like there is a lot of great stuff bubbling, on the verge of becoming scalable.”


Experimentation is crucial to mycelium becoming a norm. “Whether it’s luxury cars or fashion, innovation is made in what are considered high end, exclusive areas,” says Curtin. “But they often trickle down once they’ve been developed.” Scullin says new ideas are being explored all the time. “We are able to embed materials for function,” he says. “For example, a copper material embedded into Reishi gives it conductivity, which could turn your jacket or handbag into a smart device.”


Creativity is essential, too. Bainbridge says working with her design partners has been invaluable when it comes to making a viable alternative that is desirable for consumers. “[They] provide much needed feedback to help our engineers nail down the more elusive, less quantitative, aesthetic qualities that are necessary for Mylo’s commercial success.”


She argues that an association with a material that has serious environmental credentials will become increasingly beneficial for fashion brands: “Today’s consumers care about sustainability and ethical purchasing. They are demanding that the brands they support make choices that align with not only their aesthetics, but also with their values.”


Ultimately, Curtin argues that Mylo’s association with luxury is no bad thing. In fact, it may change how we think about what we buy, and how we buy it. “I think people who buy these objects, they are pioneers, they are helping the research of these materials,” she says. “Although it’s not luxury in what we’re used to, as in silk or gold, there is a luxury of intent: you’re supporting a new way of thinking, a new way of relating to the planet.”

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