Adidas' Stan Smith Mylo are its first mushroom leather sneakers

It wants to turn the concept into an actual product within a year.


Adidas is today debuting its first shoe made with Mylo’s “Unleather,” a material crafted from the root structure of mushrooms. The Stan Smith Mylo is a concept sneaker that uses the renewable material for its outer upper, stripes, heel tab overlay and branding. It’s part of the company’s push to only use natural materials in their shoes, like the natural rubber midsole, to reduce Adidas’ environmental impact. Only a concept, the company expects to launch a “commercially available proof of concept” in the near future. But the announcement marks another step towards, potentially, a more environmentally friendly future for fashion.

Stan Smith is Adidas’ signature tennis shoe, and has previously been released in a vegan version, albeit as a limited edition. Named after the US tennis player who endorsed the shoe in 1973, the sneaker has secured its place in fashion history with its unique spin on Adidas’ signature design. This version retains the white upper, albeit with a cream, rather than green heel pad, with the sole colored in the light brown we associate with “natural” rubber color.

Amy Jones Vaterlaus, Adidas’ head of future, says that the launch of the first Mylo sneaker is “a major step forward in our bold ambition to help end plastic waste.” In recent years, the company has been working to address its environmental impact, including working with ocean-cleanup body Parley to create clothes and footwear that use disused plastic. Since then, the company launched the fully-recyclable Futurecraft Loop sneaker in 2019, and in May 2020, the company teamed up with Allbirds to reduce carbon emissions, pledging to only use recycled plastics by 2024.

Adidas’ work was not achieved at the German company’s headquarters. Instead it enlisted the aid of startup Bolt Threads, one of a handful of companies that is developing alternative materials which could be used to supplant silk and leather. Bolt Threads’ Mylo-branded “Unleather” has repeatedly been described as looking and feeling just like leather, but requiring far fewer raw materials and energy to produce.

Leather from mushrooms

Image inside a mushroom-growing facility where Mylo is grown
Adidas / Bolt Threads

Mylo is grown at a vertical farming facility in the Netherlands, where mushrooms are grown in a manner similar to how they would develop on the forest floor. These large trays contain a growing surface — in this case, sawdust and “organic material” — which then grows mycelium into a “foamy layer” like a “big bag of smashed marshmallows.” This foam is then harvested after just two weeks, where it is then processed using a secret method the company claims uses “green chemistry principles.” It is then tanned and dyed to make a product that looks and feels like real leather, ready to be shipped to fashion houses. The leftover waste is then composted, further burnishing the claim that Mylo is better for the environment.

Bolt Threads was founded in 2009, and in 2017 introduced its first commercial project to create artificial silk fibers. In 2018, it debuted Mylo with a Kickstarter campaign to sell a bag made with the material in partnership with Portland bagmaker Chester Wallace. Deliveries of the bag were due to begin at the end of 2020, but the company said that the first production run “did not meet our standard of quality to ship.”

The company has had a longstanding association with fashion designer (and lifelong vegetarian) Stella McCartney. McCartney debuted her first collaboration with Bolt using its silk substitute in 2017, and in 2018 created a concept version of the Falabella bag, made from Mylo, for an exhibition. McCartney subsequently became the first designer to launch a garment made from the material, debuting a concept two-piece bustier top and trousers in March 2021.

McCartney’s fashion house may have been the first to sign up, but it’s now one of a quartet of names backing the company. The Mylo Consortium has invested in the company, and will be the first to access the Mylo material when it is commercially available. Adidas is the second name on the roster, followed by Lululemon and Kering. The latter is the holding company that owns (deep breath) Gucci, Alexander McQueen, Saint Laurent, Bottega Veneta, Balenciaga and Brioni, amongst others.

The Stan Smith

Image of Adidas designers creating the Stan Smith Mylo, made from mushroom leather

Martin Love, Category Director for Adidas Originals said that adapting Mylo for use in the company’s processes hasn’t taken very long. “It’s literally taken us a year, from getting a material that is ready to be trialled,” he said, “to having a concept on hand that we can say ‘hey, it’s now ready.” Much of that time, he said, was given over to “reinventing the shoemaking process,” adding that while the Stan Smith Mylo was still a concept, “in the next 12 months, we’re looking to start selling the shoe.” And that the company is in a position “where the actual material itself is [on track to be] scaled as we wish, based on how we want to roll it out.”

Jamie Bainbridge is Bolt’s Vice President of Product Development, in charge of bridging the gap between the biotechnology and fashion worlds. She said that one of Mylo’s strengths is the ability to screen out variation, ensuring greater uniformity than with a natural product like cowhide leather. “We have the ability to blend lots of material, which you wouldn’t in a cowhide [...] minimizing the differences through large batches of material.”

There is, perhaps, the perception that buying a mushroom leather product will result in people accepting something lower-quality. After all, much like other ethical alternatives, the idea is that you’re giving something up, rather than embracing something different but equal. Love said that Adidas wants these shoes to “hit the Adidas standards,” and that they “aren’t going to put out a product that consumers aren’t expecting [to last].”

The price of leather

There are a number of reasons why artificial substitutes to leather have surged in popularity over the last decade. In early 2020, a market research body said that it expected the global “vegan leather” market to increase by nearly 50 percent between 2019 and 2025. It pointed to the demand for more affordable high fashion clothes — since high-quality leather is very expensive, and a growing awareness of the climactic impact that leather can have. The fact that it is hard-wearing, supple and breathable makes it a useful material for a number of items of clothing and furniture, including footwear, handbags and seat coverings.

Leather is predominantly sourced from the hides of livestock animals, including cows, sheep, goats and pigs. The Food and Agriculture Organization of the United Nations says that livestock farming generates around 15 percent of the world’s total greenhouse gas emissions. And it’s not just greenhouse gas emissions that livestock farming is responsible for, with an Oxford University and Agroscope study adding plenty of other crimes to the charge sheet. Researchers say that beef farming not only adds emissions, but also contributes to acidification of the soil and eutrophication of the oceans, damaging their quality.

Fashion, overall, has a climate impact that is similarly misery-inducing, with the British Fashion Council saying that in 2015 textile production alone created 1.7 billion tonnes of greenhouse gases. In 2018, the UN said that the fashion industry produces around 10 percent of the world’s carbon emissions and 20 percent of the world’s waste water. The clothes that we wear — especially in a culture where they are treated as disposable — and the materials that they are made out of, are in need of dramatic reform.

Existing artificial leather is normally created either with Polyvinyl Chloride (PVC) or Polyurethane (PU) plastic. Both are oil by-products and both have a limited useful lifespan, since they are difficult to repair after being damaged, but degrade far less quickly over time. A 2003 Greenpeace report described PVC as “the single most environmentally damaging of all plastics,” thanks to its use of chlorine. Essentially, while these materials may be vegan or vegetarian leathers, they still carry an environmental cost which should make many uncomfortable.

The challengers

A number of companies are looking to create organic alternatives to leather which behave enough like tanned cowhides that people don’t notice the difference. Muskin, for instance, creates a leather-like skin from the cap of a large, inedible mushroom called the Phellinus Ellipsoideus. Zoa, created by Modern Meadow, uses cultured yeast cells, fermented to create collagen — a key protein in skin — which is then processed.

Mexico-based company Desserto is developing a form of leather made from mature leaves from a cactus bush. These leaves, which leave the bush in the ground, enabling it to grow continuously, are then cleaned, mashed and dried in the sun before being treated and molded. The company says that the leaves are not treated using toxic chemicals and can be dyed into a number of colors before being used. In its materials, Desserto says that the resulting material is cleanable, flexible and has a lifespan of around ten years.

Earlier this week, watch and luggage brand Fossil introduced its first collection of cactus leather bags in the form of the Kier tote. These bags are available in moss, wine, black and brown, and were available to order on April 12th for $298. A Fossil spokesperson added that the company has tested the bag to the same standards it would for its regular leather products, saying that “the Kier Cactus Leather Tote satisfies the same performance and durability standards as regular leather.”

MycoWorks is, perhaps, the clearest rival to Mylo in the space to craft a cleaner, better form of leather from sustainable materials like mushrooms. “We think it’s a new category, something that’s new rather than a substitute,” said said CEO Matt Scullin, co-founder of thermoelectric startup Alphabet Energy. MycoWorks’ flagship product is Reishi, a leather made from the fine mycelium of a tailored strain of fungus. Reishi has already been used in a concept bag made by French luxury house Hermés.

“We take a two-foot by three-foot tray, the tray is proprietary,” said Scullin, “we fill the tray with substrate, which is waste biomass, and then inoculate that biomass with the [fungus] strain that we use.” Scullin added that, from this point forward, the company can make alterations to the strain at the genetic level; “we have these knobs that we can turn at every step of the process to engineer the finished product.”

Once impregnated, the “mycelium wants to snake around all of the food and consume it,” which Scullin says helps to consume wasted carbon dioxide. “We get this very dense sheet of mycelium to form [...] in a very intertwined structure, and it’s that microstructure that we impart, that is the key to fine mycelium.” Scullin also explained that this process enables the company to create “true composite materials,” by embedding other material threads into the substrate at creation. “If we add cotton,” he said “the mycelium wraps around every thread of cotton, and you don’t even know that it’s in the finished product.”

Scullin said that it’s this ability to tune, reinforce and adapt the material which gives it its potential, and the interest from designers. He added that the company should have no complaints about the durability of the material compared to cowhide leather. On its website, you can find copies of Vartest analyses testing Reishi’s strength, durability and appearance, which put it on a par with a sample of cowhide leather.

As far as Scullin is concerned, not all mushroom-based leathers are created equal, and shouldn’t be seen as interchangeable. “[Reishi uses] a very different approach from mushroom leather, the stuff that our competitors are doing,” he said. “You’ve seen the photos, they put these racks in a room that they pump full of CO2 that [...] ends up with a foam of mycelium [...] and that foam is then compressed and it can be weak and uneven.”

In a statement, Bolt Threads said that it has “explored about 4,000 iterations of Mylo over the past few years to get the soft, supple and even material that is here today.” It added that “Bolt Threads won’t profess to know the technical details of what anyone else in the space is doing, so reliability of sources is something to consider.”

The future of (not) leather

For now, these materials are in sufficiently short supply that requests for a sample to feel, and photograph, were rejected. What precious little of this that is currently available is in the hands of the elite fashion companies who are looking to adopt this in their products. Certainly, with the exception of Fossil’s Cactus Leather bag, commercially-available products made with these new materials are thin on the ground. It’s not clear if we’ll see tops, pants, sneakers, jackets and bags made with mushrooms (and other plants) flooding the shops in the next few years, or at all.

Sean Gallagher’s short documentary The Toxic Price of Leather highlights the environmental cost of leather work right now. The use of chrome in traditional leather tanneries means that significant volumes of chromium-saturated water is entering the ecosystem of Kanpur, where hundreds are located. Unfortunately, there is an ecological and human cost to these processes that are constantly incurring a further debt to our future which we can ill-afford to repay. Whether it’s from mushrooms, cacti or something else, we all need to ensure that we can find safer alternatives for the future.

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