Luke Haverhals, founder and CEO of Natural Fiber Welding, a materials-innovation company in Illinois, sees himself as equal parts scientist and chef.
”We look at different inputs similar to how a chef uses eggs, milk, sugar and butter to make exactly what he wants, whether it’s a souffle that is light and airy or something that sticks to your bones,” Haverhals told Sourcing Journal ahead of the Next-Generation Bio-Based Innovation Summit earlier this month.
Natural Fiber Welding used this ingredients-first approach to create Mirum, a complex composite, derived from plant-based waste such as cork powder, rice hulls and coconut fiber, that mimics the look and feel of leather without the need for cows. In February, cult-favorite shoemaker Allbirds gave Mirum its stamp of approval, investing $2 million to add “plant leather” to its suite of materials. It plans to launch the first such shoe in December.
As traditional leather loses luster over animal-rights and environmental issues, vegan alternatives stand ready to fill the breach. These are not your mother’s squeaky pleathers or leatherettes, however. Today’s cruelty-free alternatives boast natural origins, such as pineapple leaves, cactus fronds or the root structures of mushrooms, that claim to eschew petrochemicals as much as they do cruelty by using what already exists in copious amounts.
Even so, the fervor for faux crosses generational lines. In a recent survey of more than 500 U.S. adults by the Material Innovation Initiative and North Mountain Consulting Group, 55 percent of respondents said they preferred vegan leather to the genuine article, citing animal welfare as their chief concern, followed by sustainability. But leather lovers who sought out bovine hides for their durability, aesthetics and conferred status didn’t count out ersatz versions either. Some 80 percent of them said they were “open” to purchasing a plant-based alternative, with 25 percent describing themselves as “enthusiastic.”
Vegan leathers derived from nature, rather than petroleum, have clear appeal: They don’t harm animals and won’t contribute to the planet’s worsening plastic crisis. Such next-generation leathers are also part of a burgeoning revolution that sees biomaterials as a new frontier for textiles that are less polluting, less resource intensive and more humane. While the “biobased” sector is a complex one with little regulatory oversight or even a universal lexicon, the standard bearers that are working to scale up their nature-based innovations say they offer solutions to fashion’s most pressing problems.
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Though a byproduct of the beef industry that might otherwise go to waste—or worse, the landfill—conventional leather is one of them, said Sue Levin, chief marketing officer at Bolt Threads, the San Francisco startup behind Mylo, a mycelium-based leather. While leather makers have made strides to clean up their acts, cowhide is still indelibly linked to toxic tanning practices, the potential for animal cruelty, threats to worker health and safety and the deforestation of the Amazon.
“Leather has a lot of baggage—no pun intended,” Levin said. “There’s a clear megatrend happening; as humans, we’re moving away from industrial animal agriculture because it’s usually problematic ethically and environmentally.”
Mylo, on the other hand, is not only the “most leather-like leather alternative” that she’s aware of, but it also avoids all of animal hide’s pitfalls. It has a sponginess and warmth like leather because the chitin that makes up the cell walls of mushrooms behaves similarly to collagen. Mylo also takes fewer than two weeks to grow, versus years for cattle, while generating fewer greenhouse gases and using less water and fewer resources in the process.
Supply-chain integration is less of a problem with fabricated materials like Mylo because they come in rolls that conventional machinery can handle with a few tweaks. A bigger challenge for manufacturers is ramping up their availability so they’re more than niche curiosities available only to those with deep pockets.
Despite mounting interest—searches for “vegan leather” ticked up by 69 percent in 2020, according to fashion search platform Lyst—consumers are seldom prepared to pay the so-called “green premium” that innovative materials often present, Levin said. Because finding partners that were willing to do so as it achieved price parity was essential to its mission, Bolt Threads established the so-called Mylo consortium with luxury conglomerate Kering and brands Adidas, Lululemon and Stella McCartney, which have all committed to the material for the long haul.
“We didn’t get into this to be a capsule; we didn’t get into this to do prototypes,” Levin said. “Our objective from Day One was for Mylo to not only be the most sustainable material on the planet but also the most widely used sustainable material on the planet.”
One way brands can help take plant-based leather from a flash-in-a-pan product to something with long-term potential is by committing to purchase a certain volume of the material every year. This jump-starts a “virtuous cycle” that allows biomaterial manufacturers to better forecast demand and tamp down costs, said Melanie Broyé-Engelkes, CEO of Britain’s Ananas Anam, which makes the leather-like Piñatex using the fibers of pineapple leaves that are usually discarded, left to rot or burned after the fruit is harvested in the Philippines. One of the first plant-based leathers to emerge on the scene, Piñatex has been adopted by brands such as Chanel, H&M, Hugo Boss and Sezane.
Ananas Anam’s biggest sticking point right now is locking down supply. The process has been slow-going because the company works with farmers directly to maintain full visibility of its value chain. But Broyé-Engelkes says the firm is now in a position to duplicate its model in other pineapple-growing countries, including Bangladesh and Costa Rica. This year, it’ll be onboarding five pilot sites, as well as integrating the “essential parts” of its manufacturing process. “Once we have unlocked the fiber supply, we can very easily scale the rest of the production,” she said.
Pricing is the central thrust of any conversation about sourcing, yet it’s a more nuanced issue when it comes to biomaterials, Broyé-Engelkes said. Unlike bovine leather, Piñatex and its ilk are sold in continuous sheets, free from the usual holes and defects that conventional hides bring, which cuts down on waste and therefore costs. It would also be impossible for Ananas Anam to compete against extremely cheap pure polyurethane or PVC leathers, though she said it’s important to note that the prices of such plastics don’t take into account their costs to the environment.
“Our mission is not to compete there…because, at some point, these materials will be phased out because of awareness from the end consumer, from the brands and hopefully from the government with regulations in place to address climate change,” she said. “We should be consuming less but better.”
Frankenstein fashion?
But not all plant-based leathers are equal. Some even have their detractors, such as Ashley Holding, a circular-innovation consultant who thinks many of these materials are neither worth the hype nor as natural or petrochemical-free as their marketing makes them out to be.
A brand might advertise its use of a certain natural material, for instance, only for that material to wind up in a tiny fraction of the final product. To promote strength and durability, another might bond its plant matter with virgin plastic polymers, creating a Frankenstein combination that offers the “worst of both worlds” because it can’t be recycled or composted, Holding said.
“Often the true nature of ‘plant leather’ materials can be hidden, so it’s good to dig a little deeper and find out exactly what is in them,” he said. “They might be mostly plastic with synthetic additives, which is not the impression that their name suggests.” This is also why some plant-based leathers describe themselves as only “partly biodegradable,” which Holding said is a misleading claim because “either the whole material is biodegradable, or it isn’t.”
It’s also important to pay attention to any additional chemical processing in the mix, he added.
“After the initial formulation, there isn’t as much additional chemical ‘processing’ as with animal leather, although they will typically include a range of binders and additives, which may not always be advertised,” Holding said.
Haverhals says Mirum is unique because it’s the only plant-based leather replacement on the market that doesn’t contain petrochemicals of any kind, allowing it to be “completely circular,” meaning it can be dissembled at the end of its life and all its components fed back into the Mirum production process.
Other brands might struggle to do the same because going completely natural means giving up some of the performance characteristics that brands and consumers desire from leather. Mylo, according to Bolt Threads, is currently certified as 60 percent to 85 percent bio-based under the German DIN-Geprüft standard because it employs “some amount” of petrochemicals in the finishing process.
“We believe 100 percent bio-based is the right goal, [but] we also know that a material’s potential for impact depends on brand and consumer adoption, and a majority of consumers will not accept big sacrifices in quality compared to leather,” she said. “We have not seen a 100 percent bio-based product yet that meets brand and consumers requirements for softness, strength and suppleness, but we will keep working toward that goal.”
All inputs used are “based on rigorously applied principles of green chemistry and minimal environmental impact,” Levin added.
Ananas Anam uses a water-based polyurethane coating, compliant with the European Union’s REACH chemical regulations, that accounts for 10 percent of Piñatex’s total composition. Broyé-Engelkes says the company is working on it. This year, it rolled out a bio-based resin that will halve the amount of polyurethane it uses, meaning the product will be 95 percent natural.
“It’s as high as you can go while maintaining the properties that are required in different applications,” she said. “[But] we have a roadmap to achieve 100 percent natural content; it’s just a matter of time to implement that and get the recipe right.” Neither Mylo nor Piñatex is currently biodegradable.
All of this might be confusing to the average consumer, who may not always appreciate the nuances of a material. Which is why there have been calls—including from the manufacturers themselves—for some manner of framework that regulates biomaterial claims and guards against greenwashing. This could include legislation.
The biomaterials industry has its share of “transparency issues and hype, especially from the biotech sector,” Haverhals said. “There will be few technological answers so long as the key problems to be solved are not properly defined [or] understood.”
Levin agrees that until the sector achieves something akin to the U.S. Environmental Protection Agency’s fuel-economy standards for cars, people are going to “say absolutely ridiculous things.”
“Please, we raise our hand and welcome regulation, particularly around claims,” she said.
Still, the upswing of interest in alternative materials is more than a love of the novel. Both the ballooning global population and the increasing ecological and ethical burden of traditional materials, Levin said, make the mandate for companies like Bolt Threads abundantly clear. For biomaterial firms, simply reexamining the status quo is a step forward. But it’s equally important to manage expectations.
“We have to look to biology for new innovations because the extractive processes we’ve been using to make consumer products can’t continue indefinitely,” Levin said. “But those solutions also need to be scalable.”