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.
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.
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, and claim to eschew petrochemicals as much as they do cruelty by using what already exists in copious amounts.
Lux Research, a Boston technology research firm, estimates that annual sales of “low-complexity” leather alternatives, which include fruit- and vegetable-derived materials and recycled-material leathers, are likely to reach $1 billion by 2025 if technological advances and consumer interest continue apace. And if these leathers can reach scale and match the price of natural leather, said senior research associate Tiffany Hua, they will “disrupt the leather industry.”
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.
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 deforestation in 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 like 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.
“There’s a clear megatrend happening; as humans, we’re moving away from industrial animal agriculture because it’s usually problematic ethically and environmentally.” — Sue Levin, Bolt Threads
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 aid in the achievement of 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 legs 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 embraced 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 will 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.”
But such ersatz hides may not be as natural, sustainable or chemically benign as their marketing frequently makes them out to be. While every brand has its own secret sauce, experts say that many of them involve petrochemical-based polymers, solvents, binding agents or plasticizers that belie their plucked-from-nature narrative.
Indeed, one typical approach by the makers of biomaterials is to sandwich the organic matter between layers of polyurethane, apply a polymer-based topcoat and then emboss the surface to give it a leather-like appearance.
“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,” said Ashley Holding, a circular-innovation consultant. “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.”
Plastic brings with it a heavy toxic burden. A recent study of popular leather mimics by Germany’s Filk Freiberg Institute, which tests and analyzes flexible multilayer polymer materials for standards organizations such as Oeko-Tex, identified restricted substances, including butanone oxime and traces of diisobutyl phthalate in AppleSkin, made from apples, and toluene in Vegea, derived from the stalks, skins and pips of grapes. Piñatex, a product of discarded pineapple leaves, showed diisobutyl phthalate. Desserto, which bills itself as a “vegan cactus leather,” contained butanone oxime, toluene, free isocyanate, the pesticide folpet and traces of diisobutyl phthalate as well.
That plant-based alternatives use polyurethane resins has been something of an open secret, said Martin Mulvihill, co-founder and managing partner at Safer Made, which invests in companies and technologies that reduce people’s exposure to toxic chemicals. Polyurethane, which comprises low-molecular-weight molecules known as isocyanates, often uses solvents such as toluene and dimethylformamide in its manufacturing. “It is not surprising that some of these will still be contaminated,” he told Sourcing Journal.
But Raquel Prado, head of research and sustainability at Ananas Anam, refuted Filk’s conclusions, citing Piñatex’s certificate of compliance with the European Union’s Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation. “This means there are no harmful substances in Piñatex,” she said.
A spokesperson for Adriano Di Marti, the Mexican producer of Desserto, told Sourcing Journal that its material doesn’t contain butanone oxime or diisobutyl phthalate because the substances aren’t used at the production site. There might be traces of diisobutyl phthalate and toluene in “older versions” of Desserto, but since the current form features a water-based adhesive, no such chemicals are being intentionally applied.
“Our cactus plantations are 100 percent organic and certified by the U.S. Department of Agriculture; we don’t use any chemicals on our cactus fields,” the spokesperson added. “As our products are produced under commercial industrial conditions, the presence of trace quantities of impurities cannot be excluded. But every effort is made to ensure that they are at a minimum level.”
Umberto Bacenetti, CEO of Mable, which manufactures AppleSkin for Italian company Frumat, said that AppleSkin is a collection of more than 20 different products made with different processes but that all are produced in compliance with REACH regulation.
“We believe that the Filk report gives incomplete and misleading information in the struggle of underlining the excellent performances of animal leather in comparison to the sustainable materials that are gaining [a] place in the market,” Bacenetti said. “How come there is no analysis on the hazardous chemicals in animal leather? Heavy metals, azo dyes and many others are commonly used in the tanning industry, but there is no mention of [them] in the report.”
Vegea did not respond to a request for comment.
Certainly, cowhide isn’t necessarily better than its plant-based counterpart, said Mulvihill of Safer Made. While the noxious chemistries in cowhide are different, there is some overlap, he added.
“There is a lot of leather that is also coated with polyurethane, which may have the [same] solvent issues,” he said. “You also have the hide preservation process and tanning process which both use a lot of hazardous chemicals, including halogenated antimicrobials and chromium VI. But a lot will depend on the individual supply chains.”
Because it’s difficult to make an apples-to-apples comparison between bovine leather and its plant-based counterpart, what matters is investigating each material on a case-by-case basis, said Tara St. James, founder of textile consultancy Re:Source(d). Just as “vegan” isn’t synonymous with “sustainable,” neither should all animal leather be tarred as bad, she added. An Italian tannery known as Be Green, for instance, is working towards a metal-free tanning process. Timberland, to name another example, has partnered with Colorado’s The Savory Institute to promote regenerative cattle-ranching practices.
Not all vegan products are plastic-based, either. Uggs recently debuted a sandal embellished with faux fur derived from Tencel-branded lyocell, which comes from trees. Allbirds is investing $2 million to add Natural Fiber Welding’s “plant leather”—described as the only vegan leather replacement on the market that doesn’t contain any petrochemicals—to its materials suite. It plans to launch the first such shoe in December.
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 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 finishing. (Mylo wasn’t included in Filk’s study.)
“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,” Levin 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.
“At the end of the day everyone wants the Holy Grail: a renewable, compostable, high-performing, pleasing material, at the cheap price of petrochemical synthetics.” — Suzanne Lee, Biofabricate
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.
Suzanne Lee, CEO of Biofabricate, a New York-based platform for biomaterial innovators and consumer brands, says that the fashion industry “seriously needs to level up” its understanding of biomaterials, which “mostly aren’t made up of 100 percent bio content, nor does the term ‘biomaterial’ in any way indicate biodegradability of any kind.”
Though standards might provide a useful guide, navigating the vast landscape of seals and certifications can make for a vertiginous experience, she added. Biomaterials, with their diversity of ingredients and technology processes, can also be difficult to corral under one universal benchmark.
“At the end of the day everyone wants the Holy Grail: a renewable, compostable, high-performing, pleasing material, at the cheap price of petrochemical synthetics,” Lee said. “As far as I know it does not exist. Meanwhile, we live in a world of compromise. As a brand you have to ask: ‘What do we care most about? Is it the origin of a feedstock? Is it the chemistry used? Is it the end of use? Is it the price?”
This article is part of Sourcing Journal’s Material Innovations 2021 Report. To download the full report, click here.