Mylo

THE BASIC IDEA

Mylo is based on the idea that leather-like materials can be grown from fungal biomass instead of sourced from livestock or built mainly from fossil-based plastics.

WHY THIS TERM EXISTS
The term exists because fashion needed a name for a branded mycelium material that promised a different route to leather substitution: biological growth rather than animal agriculture or conventional synthetic coating.

SUSTAINABILITY STACK
Mylo affects Materials & Biology by replacing animal hide with mycelium biomass, and Production & Supply Logic by shifting leather supply toward controlled cultivation and fabrication.

HOW IT IS MADE
Mylo is made by feeding and growing mycelium on inputs including corn stalks and supplemental nutrients while tightly controlling temperature and humidity so the mycelium self-assembles into a dense mat. That mat is then processed, compressed, and tanned to produce a leather-like material with the thickness and feel required for fashion applications. Stella McCartney describes the process as vertical farming using air, water, and mulch, with the mycelium grown in less than two weeks.

BY THE NUMBERS

¹ Stella McCartney. (2023, March 2). Mylo™: Mycelium-based alternative to animal leather.
² Stella McCartney. (2023, March 2). Mylo™: Mycelium-based alternative to animal leather.
³ Bolt Threads. (n.d.). Mylo™.
⁴ Stella McCartney. (2023, March 2). Mylo™: Mycelium-based alternative to animal leather.

THE HONEST TENSION
Mylo is one of the clearest examples of fashion wanting a material to mean two things at once: biological progress and commercial readiness. It proved that luxury brands and consumers would take mycelium seriously, but proving desirability is not the same as proving industrial viability. The material became iconic faster than the manufacturing system matured.

WHAT IT DOES NOT AUTOMATICALLY SOLVE
Mylo does not automatically solve durability, coating chemistry, cost, energy demand, end-of-life recovery, or scale. Nor does the use of fungal biomass by itself guarantee a plastic-free or fully low-impact product system. These limitations are consistent across reviews of mycelium leather, even when the overall environmental case remains promising.

WHAT MAKES THIS HARD
Unlike waste-based filler materials, Mylo depends on bespoke growing infrastructure, careful environmental control, and post-processing that must be reliable enough for luxury-grade performance. That means the challenge is not just inventing the material, but scaling the whole cultivation-and-finishing system economically.

WHERE THIS SHOWS UP IN A FASHION BUSINESS
Product Creation: as a leather substitute for bags, panels, garments, and accessories.
Design: where teams want a softer, leather-like handfeel with a strong biomaterial story.
Marketing: because Mylo is highly legible as an innovation narrative.
Supply Chain: because it changes sourcing from hides or conventional synthetics to controlled biological cultivation.
Operations & Reporting: because brands need to substantiate what part of the product is actually Mylo and how it performs.

WHO THIS MATTERS TO
Designers, sustainability managers, accessory developers, sourcing teams, innovation leads, and executives all care about Mylo for different reasons: aesthetics, environmental positioning, material risk, supplier dependence, and future leather strategy. It also matters to journalists because it became one of the most visible symbols of biomaterial fashion.

HOW THIS TERM IS COMMONLY USED TODAY
Today, “Mylo” is often used as both a specific branded material name and a broader cultural shorthand for mushroom leather innovation. That dual use can blur the difference between Mylo itself and the wider category of mycelium-based leather alternatives.

COMMON MISUNDERSTANDINGS
Mylo is not a generic term for all mushroom leather. It is not automatically plastic-free just because it is bio-based. It is not proof that mycelium leather has fully scaled. And it is not identical to every other fungal leather material on the market.

WHERE THIS WORKS TODAY
Mylo has worked best in premium, controlled applications where craftsmanship, novelty, and material storytelling matter — especially luxury bags, showcase garments, and selected accessories. Stella McCartney’s garments and Frayme Mylo bag are the clearest public examples.

PROPOSED SOLUTIONS OR APPLICATIONS
The strongest use case for Mylo is not to replace all leather immediately, but to prove out a new material logic in targeted categories, then improve manufacturing, consistency, and cost over time. That is partly an inference, but it follows from how the material has been commercialised so far.

SCALABILITY ASSESSMENT
Moderate. Mylo proved luxury relevance through Stella McCartney’s early garments and the Frayme Mylo bag, but scaling depends on bespoke vertical-farming capacity. It is viable for premium partnerships, yet broader rollout still relies on more standardised performance, lower costs, and infrastructure expansion.

CURRENT STATE OF DEVELOPMENT
Maturity level: moderate / constrained scaling. Mylo is no longer just a concept, because it achieved real product visibility and commercial pilot applications. But it is not yet a mainstream replacement material across fashion.

ENERGY AND RESOURCE FOOTPRINT
Mylo can reduce land use and the long biological timelines associated with livestock leather, and Stella McCartney says its vertical farm was powered by renewable energy. But it still requires energy for climate-controlled growth, processing, finishing, and facility infrastructure. Water, emissions, and waste profiles depend heavily on the final product system and post-processing, not only the mycelium itself.

DATA QUALITY NOTE
Data quality around Mylo is uneven in public use. Official brand and company sources are strong on narrative and selected process facts, but less detailed on full comparative lifecycle disclosure in a way that allows easy product-level benchmarking. Academic work on mycelium leather is broader than Mylo itself and should not be assumed to map perfectly onto Bolt’s specific formulation.

SYSTEMS INTERACTION
Mylo sits at the intersection of leather substitution, biomaterials, luxury innovation, fossil-material reduction, and biotechnology-led supply change. It also reveals that changing materials often means changing infrastructure, financing, and industrial logic at the same time. The second point is an inference from the way Mylo has developed.

ECONOMIC BARRIERS
The main barriers are capital-intensive facilities, controlled growth infrastructure, production consistency, and the cost of making a luxury-grade biofabricated material at useful volume. Those constraints are a recurring theme in reviews of mycelium leather and in industry discussion around Mylo’s slower-than-hoped scaling.

CONSUMER AND CULTURAL PERCEPTION
Consumers tend to read Mylo as futuristic, ethical, and lower-impact, which is exactly why it became such a powerful fashion symbol. But that symbolism can flatten the practical reality: it is still a highly engineered material, not just a mushroom grown into a handbag.

QUESTIONS THE INDUSTRY HASN’T ANSWERED YET
Can mycelium leather reach true industrial scale without losing its environmental advantage? How should brands compare Mylo fairly to animal leather and polyurethane synthetics? And what level of post-processing still counts as a meaningful biomaterial improvement? These are inference-based framing questions, but they arise directly from the current evidence base.

KEY INSTITUTIONS
Bolt Threads is the defining company behind Mylo. Stella McCartney is the most important fashion brand in its public cultural adoption. Academic materials research on fungal leather provides the wider scientific context for understanding its promise and limits.

HOW TO EVALUATE QUALITY
Good use of the term should distinguish Mylo from generic mushroom leather, explain that it is a branded mycelium material, and avoid implying that product launch equals mature scale. Stronger analysis also separates the biological feedstock from the total finished-material system.

ECOLOGICAL SYSTEMS NOTE
Mylo matters because it reframes leather not as something that must come from livestock, but as something that can potentially be grown from fungal biology. Its ecological significance lies in that shift in material logic, even though the finished product still depends on industrial processing and system design.

RELATED TERMS
Mycelium leather — the wider category to which Mylo belongs.
Alternative leather — the broader commercial category.
Biofabrication — the production logic Mylo helps popularise in fashion.