A small number of very high-profile tanners have begun to add mycelium-based materials to their product offerings, not as a competitor to leather but as a much-needed replacement for plastic.

Leather manufacturers have traditionally expressed vehement opposition to alternative materials and have held firm to the notion that no material can work as well in footwear as leather does.

Alternatives have left a lot to be desired; most that have the physical properties that footwear manufacturers need are types of plastic (sometimes with fancy names). In a study in 2021, Germany-based testing and research institute FILK ran a set of studies on leather and eight widely talked about alternative materials. The tests included water vapour absorption and water vapour permeability, on which the alternative materials scored “significantly lower than leather”. Leather also showed a superior performance in flex and tear-resistance tests, indicating greater durability. 

Price sensitivities

Away from the top grades, leather has also been cheap for a number of seasons now and even though, as for everyone, energy, chemicals and labour costs have been going up quickly for tanners, hide prices are low. At the start of 2018, it was difficult to find steer hides in the US for less than $50 per piece, with many cowhides in the high $40s. In January 2023, there were steer hides available in the US for under $20 and cowhides for under $10. At the end of the same month, leatherbiz.com published this comment from a seasoned industry observer in its Market Intelligence newsletter: “The price of leather in the mass market cannot drop any lower. [Nevertheless] even if this is not officially communicated, the big sports and casual shoe brands have decided almost to stop using leather by 2025. Leather will only remain where there are special requirements or in the most expensive lines.”

The producers of one alternative in particular, mycelium, believe that this trend represents a great opportunity for them. Mycelium is the underground root-like structure through which mushrooms absorb nutrients. A number of biotech companies have developed methods for making mycelium into fabric or foam-like substances. Without too much fanfare, the mycelium developers appear to have won the tacit support of an unlikely group of partners: major leather manufacturers. Now, their materials are going through a curing, finishing and cutting process in tanneries and footwear is one of the main target application areas for the cut parts.

Additional sustainable products

It is more than two years now since ISA TanTec announced its decision to add a new division to a footwear-focused group portfolio that includes large, high-tech leather manufacturing facilities in China, the US and Vietnam. It launched its Creation of Sustainable Materials (COSM) business unit to develop “additional sustainable products” that it is now manufacturing alongside leather. COSM makes bio-based materials that offer an alternative to plastic-based synthetics, the group has explained. A first product, HyphaLite HP, came to market in 2021. It is 80% bio-based, complies with brands’ restricted substance lists and is, according to ISA TanTec, biodegradable. Hyphae are the filaments that make up mycelium. The Lite part of the product’s name comes from the LITE (low impact on the environment) system that ISA TanTec uses to produce all of its materials while keeping its consumption of water, chemicals and energy low.

HyphaLite HP is made up of 64% viscose and lyocell fibres, 19% natural rubber and 17% mycelium-based “structural ingredients”. The manufacturer has measured the mushroom content at 250 grammes per square-metre.

By the end of 2022, COSM had also launched a pure white 92% viscose and lyocell version called NatraLite for sports shoes, and a felted-wool substitute called TerraLite, made entirely from viscose and lyocell. ISA TanTec said COSM had already become “a solid pillar”, supporting the group’s growth and sustainability initiatives. Chief executive, Uwe Hutzler, said it had taken innovation, resources, and determination to push the new products forward, but he said the group was now receiving “very positive market feedback” about these COSM materials.

Natural match

From the mycelium side of the fence, California-based biomaterials startup MycoWorks has had much to say about reaching out to tanners. It claims that Reishi, the commercial name it has given its mycelium material, is “the first natural material to match the performance of the finest leathers”. It announced in 2021 that it was working with luxury group Hermès to develop a version of the Paris-based brand’s Victoria bag using mycelium. This involved taking lab-developed material from MycoWorks and tanning and finishing it in Hermès-owned leather manufacturing facilities in France before delivery to the luxury brand’s ateliers for cutting and making into bags.

This project generated enormous publicity for MycoWorks, although few of the bags appear to have been made and the much-vaunted product was not available to buy on official Hermès e-commerce sites at the start of 2023. Later in 2021, the two companies generated more news when a former chief executive of Hermès, Patrick Thomas, announced he was joining the board of MycoWorks. He had stepped down from his role at Hermès in 2014 but was a well known figure in luxury leathergoods circles. With a similar take to ISA TanTec’s, Mr Thomas has said he does not view MycoWorks’ contribution to brands such as Hermès as a threat to the leather industry. He describes products like the mycelium-based Victoria bag as “an additional category”, which will attract vegan consumers. Mr Thomas, who remains on the board of the mycelium producer, has predicted that this new category could provide at least 10% of overall sales in the luxury goods industry in the next 20 years. 

On the money

This figure would represent a very large amount of money. Specialist market research firms Bain and Altagamma have estimated that the global luxury market is likely to have generated revenues of around €350 billion in 2022 and to be on course for achieving a figure of more than €550 billion in 2030. A 10% share of that would, if Patrick Thomas’s assessment is accurate, give the “additional category” a global value of more than €50 billion in its own right.

MycoWorks is optimistic about carving out a handsome share of this. It opened an office in Paris towards the end of 2022. At the start of 2023, it announced plans to set up its first full-scale mycelium manufacturing facility in South Carolina, with production starting there in 2024; this project will create 400 new jobs. Meanwhile, on the tanning side, it has launched a search for a director of tannery management. This person will be based in the Catalan town of Igualada, one of the most famous tanning clusters in the world. Not all the details are clear but in the description MycoWorks has offered, the role will involve overseeing operations at a tannery in Igualada, and arranging technology transfers among “all four of MycoWorks’ partner tanneries”. It said: “This role will oversee three functional groups at the tannery in Igualada: process engineering, tannery and finishing operations, and supply chain.”

This makes it sound as though MycoWorks has acquired one of the 50 businesses in the Barcelona Leather Cluster to establish a set-up of its own there. However, our enquiries suggest that it has not, so far, taken ownership of any of Igualada’s tanneries. It has been active in the area, seeking partners to work with so that it can improve the stability of the finished material it offers to brands, but it is reliant on local leather producers to make space for it in their production schedules. Perhaps it intends to acquire a tannery in the months ahead.

Polyurethane problem

Another producer of mycelium, New York-based Ecovative, entered this discussion at the end of 2022 when it announced a partnership with footwear-focused leather manufacturer Ecco Leather. Ecovative will supply Ecco with “custom-tuned mycelium” that its in-house leather division will make into materials for the parent footwear group’s own use and for the use of partner companies that its leather division supplies. Chief executive of the group, Panos Mytaros, has told World Leather, our sister publication, that the company remains committed to producing and using leather. Mr Mytaros used to run Ecco Leather, and explained that Ecco Leather had spent seven years looking into the possibility of making a new material that was “grown from nature” and free from polyurethane and other plastics, but not animal-based.

“The world needs polyurethane-free material,” the Ecco chief executive said. But he insisted that no one should interpret this development as a move away from leather on Ecco’s part. He said it was simply a question of giving consumers variety. “People can interpret things however they want, but this is not an alternative to leather,” he said of the mycelium material. “We are clear that Ecco Leather is a leather maker and our commitment to leather remains. But we are a leather maker that pushes innovation and is trying to make an old-fashioned industry modern.”

He told World Leather that Ecco Leather would continue its efforts to help the wider leather industry claim its place in the circular economy, but he added that he feared circular innovations his company has already come up with, mentioning the DriTan tanning technology it introduced in 2018 as an example, were receiving less attention than they deserve. At the time of DriTan’s launch, Ecco Leather said it would allow it to save 250 million litres of water per year at its tannery in the Netherlands. Perhaps the publicity its partnership with Ecovative generates can help it spread its sustainability story more widely.

Shoes made from ISA TanTec’s HyphaLite HP material.  
Credit: ISA TanTec

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