Stella McCartney, an award-winning English designer and the daughter of Sir Paul McCartney, has introduced her first clothing collection made almost entirely of a new “mushroom” leather alternative. 

Under her namesake label, now in its 20th year, McCartney collaborated with longtime partner Bolt Threads to create a two-piece capsule using Bolt’s Mylo material, a vegan, plant-based, petroleum-free leather. 

Mylo is made from mycelium, the vegetative part of a fungus that branches out to form a sprawling, root-like structure to absorb nutrients from its environment. For context, the bulbous mushrooms we see above ground are the fruit of mycelium, making “mushroom” leather a bit of an oversimplification, but much better than fungi leather. 

Mycelia not only grow by breaking down organic matter around it but they also provide nutrients back to surrounding plants and trees. Fungi themselves are fascinating, and immensely important to maintaining the balance of our ecological systems. “It brings sustenance to all living species and is the literal world wide web,” reads Bolt’s website.

So, how did mycelium become a leather? It starts in nature, of course. If mycelia are left to decompose a fallen tree in the woods, they’ll come together to form a dense piece of foam. It has taken humans some time to harness this power, but since 2007, Ecovative Design has been developing alternatives to polystyrene and plastic packaging by growing mycelium in agricultural waste. 

Then in 2013, MycoWorks started producing mycelium-based furniture, bricks and leather. Soon after, the material innovators at Bolt Threads, along with a team of inquisitive scientists and engineers, developed a state-of-the-art process to grow and transform mycelium into a quality leather alternative. The process begins with mycelia cells grown on beds of sawdust and other organic material. Billions of cells then cultivate to form an interconnected 3D network which is processed, tanned, and dyed to make Mylo.

It feels and performs just as traditional animal leather does, but it’s entirely plant-based and thus biodegradable. And unlike many synthetic leathers, it’s plastic free as well. 

Now, back to McCartney. The designer has been working with Bolt Threads since 2016, when she first visited the company’s California headquarters to explore its spider-free silk. Since then, she has been working with Bolt to develop and scale Mylo for the greater fashion community. She partnered directly with their team of scientists to perfect its shape, feel, weight and durability, and then introduced the first Mylo prototype of her Falabella bag in 2018. Then in 2020, she helped form a consortium with Kering, adidas and Lululemon to bring more investment to Bolt and Mylo.

This past week, McCartney, the winner of 2017’s Special Recognition Award for Innovation at The Fashion Awards, presented the latest milestone for Mylo — a full outfit made from the material. Handcrafted at her London atelier by laying panels of Mylo atop recycled nylon, the very first ever Mylo garments appear in the form of a bustier top and matching trousers. 

“These rare, exclusive Mylo pieces embody our shared commitment with Bolt Threads to innovate a kinder fashion industry – one that sees the birth of beautiful, luxurious materials as opposed to the deaths of our fellow creatures and planet,” says Stella McCartney on her website.

In an exclusive interview with Vogue, McCartney added, “I wanted to do the ready-to-wear to give a bit more insight into how much you can do with this material, and how it can be swept across the industry to actually replace leather. That’s obviously the ultimate goal.” 

She also mentioned to Vogue that until recently, it wasn’t possible to create sheets of Mylo that were large enough to cut into pants, and the early iterations of the material were “quite stiff.” 

This is only the latest sustainable initiative in McCartney’s revered career. A lifelong vegan and animal activist, McCartney has never used animal hides or fur in any of her collections. She has often used her platform to expose the cruelty and negligence that pervades the leather industry, and its subsequent environmental damage.  

Unfortunately however, the capsule is not for sale. Instead it represents “the potential of this next-generation material and [paving] the way for future commercial offerings.”

The next frontier in the evolution of Mylo and mushroom (or mycelium) leather is industrial scaling to meet the growing demand for Earth-friendlier materials. According to Infinium Global Research, by way of vegconomist.com, the vegan leather market should reach $90 billion USD by 2025. Once this innovation can be mass-produced and at fair prices, we should most certainly see it adapted throughout the various fashion and design communities around the globe.

“This is the future of fashion,” McCartney told Vogue. “If we can get this right, then we can really make a huge impact on the planet.”

For more news on plant-based materials, check out our story on Allbirds’ partnership with Natural Fiber Welding.