Stella McCartney-backed leather alternative Mylo halts production

To become a Vogue Business Member and receive the Sustainability Edit newsletter, click here. Mylo — the mycelium-based leather alternative used by Stella McCartney, Kering and Adidas — has ceased production, Vogue Business has learned. Developed by California material innovation startup Bolt Threads and launched in 2018, the bio-based material had been widely lauded as a more sustainable alternative to conventional animal leather. Bolt Threads CEO Dan Widmaier says Mylo was “devastatingly close” to commercial scale, but inflation and waning funding opportunities have brought the company to a standstill. Bolt Threads has undergone two rounds of layoffs so far this year, one in Q1 and another in Q2. “We are not immune to the same macroeconomic pressures everyone else is facing, so we have paused Mylo to reassess what works and what will work in the future,” Widmaier tells Vogue Business. It’s not out of the question that Bolt Threads would sell the technology in the hopes of getting Mylo to market. “There’s no finality to this story yet. Humanity needs a more sustainable future or we will cook ourselves on this planet with climate change, and fashion has a huge role in that. My hope is that we solve this problem for the good of everyone on the planet — that’s why all options are on the table.” Bolt Threads was co-founded in 2009 by Widmaier and CTO David Breslauer. The venture-backed business has topped $300 million in investment to date, but has never disclosed its valuation publicly. “Scale-up is the most expensive and hardest part and there are no shortcuts,” says Widmaier. Despite the alternative materials space gaining traction in recent years, with brands and startups working to bring non-animal products to market, Widmaier says that investors’ attention has now been pulled elsewhere. “Fundraising has been a challenge across the whole space for the last 18 months. Those who have been able to raise funding mostly deal with AI.” The struggle for scalability Mylo is among a wave of alternative leathers — including Reishi from Mycoworks, Mirum from Natural Fiber Welding and Forager from Ecovative — that have garnered attention as criticism of animal leather’s environmental impact, and consumer demand for vegan products, have grown. Most have struggled to reach commercial scale. According to Widmaier, Mylo had a manufacturing capacity of one million square feet per year at the expected quality before it ceased production. There had been promising signs that Mylo was slowly nearing scalability, largely led by early adopter Stella McCartney. The luxury brand unveiled the first product made from Mylo — a prototype of its Falabella bag — in 2018, followed by two exhibition-only garments — a bustier top and utilitarian trousers which combined Mylo with recycled nylon scuba — in March 2021. The Mylo iteration of its Frayme bag was the first commercially viable Bolt Threads product, debuted during the Autumn/Winter 2021 collection and launched in a limited-edition run in 2022. Other brands soon followed. Adidas announced that it had made its first Stan Smith sneakers in the alternative leather in 2021, Lululemon created its first yoga products made from Mylo later that year, and Ganni launched a small range of accessories made from the material in 2022. In October 2020, a consortium of four companies — Stella McCartney, Kering, Adidas and Lululemon — invested seven-figure sums in Bolt Threads in order to help develop the alternative leather and produce the material on a larger scale. These were not equity investments, says Widmaier, but “a commitment to help bring the product from lab to real products”. Kering and Ganni declined to comment. Adidas and Lululemon did not respond to requests for comment by the time of publication. “The Bolt Threads team pioneered an entirely new form of material innovation, leading the way for others to continue their mission of creating a fashion industry that is kinder to our fellow creatures and Mother Earth,” the Stella McCartney team said in a statement to Vogue Business. “We are incredibly proud of the work we have done together since our collaboration began in 2017. Next-generation innovators have the vision, but it is up to brands and consumers to see the value in supporting start-ups that disrupt our industry for the better. At Stella McCartney we continue to support alternative materials for a more sustainable future.” In February 2023, Stella McCartney — which had previously lamented the design limitations of Mylo — sent updated versions of the Falabella and Frayme bags down her Autumn/Winter 2023 catwalk, using Mirum, the Mylo competitor made by Natural Fiber Welding, as well as the Mylo Frayme bag in a new white colourway. However, Widmaier suggested that the emergence of other competitors on the market was not a factor behind the decision to halt production on Mylo. “I saw no tangible effect from many of the participants entering the market,” he says. The future is uncertain for Mylo’s brand partnerships. “I’m proud of the work the consortium members and others did to make real products from Mylo and bring them to market,” says Widmaier. “Depending on the path forward that emerges in the next few months, those products may resume production again.” Boston-based cell programming platform Ginkgo Bioworks formed a multi-project partnership with Bolt Threads in October 2022, hoping to increase the growth rate of Mylo and lower production costs. “The potential for animal-free leathers is huge and we will be here when Bolt Threads picks the Mylo line of work back up,” says Ginkgo Bioworks CEO Jason Kelly. Bolt Threads was initially known for Microsilk, a protein-based silk alternative, but turned its focus on Mylo after it launched in 2018, as it believed it was more commercially viable. While Mylo has been paused, Widmaier says the company’s bio-based, biodegradable and vegan polypeptide, B-silk Protein, is still in production. Widmaier sees Mylo as a casualty of more systemic issues. “Innovation is hard and expensive, especially for physical goods, but I hope the industry comes to embrace that because these challenges absolutely need to be solved.” Despite the current setbacks, he remains upbeat that attitudes are shifting, even if funding is drying up. “For a long time, the need for more sustainable alternative materials was not taken seriously in this industry, but I think that has changed now. Everyone recognises that this is a problem, and consumers want solutions. That said, the sum total of alternative materials going into sold products and generating revenue right now generously rounds down to zero. It’s all future adoption that needs to happen to really change the industry.” Comments, questions or feedback? Email us at feedback@voguebusiness.com. More on this topic: Next-gen materials gain pace, but systems change is too slow Materials startup asks brands to eliminate virgin leather if they want alternative Stella McCartney to debut first-ever mushroom leather bag

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