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We're using mycelium, the underground root structure of mushrooms, to make an entirely new, leather-like material.

Mycelium is the underground root structure of mushrooms. It grows as tiny threads that form vast networks under the forest floor.

We developed Mylo™ from mycelium cells by creating optimal growing conditions for it to self-assemble into a supple, sustainable material that looks and feels remarkably like animal leather. Mylo™ can be produced in days versus years, without the material waste of using animal hides.

The process begins with mycelium cells.

We grow the cells in beds of corn stalks with additional nutrients.

Billions of cells grow and form an interconnected 3D network.

We compress the network to make a 2-D material and tan and dye it to make Mylo™.


Frequently Asked Questions


What is Mylo™?
Mylo™ is a material made from mycelium, the underground root structure of mushrooms. We carefully control the mycelium’s growth conditions to produce a substrate that can be cured and tanned into a soft, supple material that looks and feels like leather.
What is mycelium?
Mycelium is the underground root structure of mushrooms. It’s made up of billions of tiny branching cells, which form a 3D micro-scale mesh structure. It holds the forest floor together and acts as nature’s recycling system by releasing enzymes that break down natural materials and release nutrients into the soil.
What are the benefits of Mylo™?
  • Mylo has a soft, supple, warm feel.
  • It’s strong, and abrasion resistant.
  • Mylo is remarkably leather-like, but no animals are used in making it.
  • Mylo grows in a matter of weeks, compared to animal hides which take years to grow.
  • Because we carefully control its environment, we can direct the mycelium’s growth and control the final material’s properties including thickness, shape, and more.
  • Compared to synthetic leathers which are made from polyurethane, Mylo feels natural and has better moisture management properties.
  • Mylo also has the potential to be significantly more sustainable than leather and other leather substitutes (see below).
Is this leather?
No. The term leather is reserved for animal hides, and animal hides are made of collagen. Mylo™ is made from 100% mycelium, and there is no collagen in Mylo™.


How do you make Mylo™?
We use corn stalks and supplemental nutrients to feed and grow our mycelium. We precisely control growth conditions like temperature and humidity to encourage the mycelium to grow upward and self-assemble into an organized mat of interconnected cells. Their connections give the material strength. We then use a natural tanning process and compress the mat to be as thin or thick as we’d like the final material to be. At this point the mycelium is no longer growing. The final step is to imprint any desired pattern, which gives us the final material.
Is this the same technology you use to make Microsilk™?
No, our Microsilk™ technology involves engineering yeast to produce protein materials. With Mylo™, we grow mycelium, which we process into the final Mylo™ material.

Our friends at Ecovative pioneered this mycelium fabrication technology, which literally grew out of the great work they've been doing in creating soft flexible foams. We were blown away, and thrilled when they agreed to allow us to help develop it into a commercially viable new material. We’ve established a long-term partnership with Ecovative to optimize this technology and put processes in place to produce commercial-ready Mylo™ material and bring products to market that consumers will love.
Are these mycelium genetically engineered?
No, instead we carefully control the wild spores’ growth conditions like temperature and humidity to engineer the final material’s properties.


How sustainable is it? Is it biodegradable?
Unlike making leather, the process of making Mylo™ doesn’t involve raising and sacrificing livestock, or any of the associated greenhouse gases or material wastes. Those impacts are substantial: Livestock use an astonishing 30% of the earth’s entire land surface and cattle-rearing generates more global warming greenhouse gases, as measured in carbon dioxide equivalent, than all transportation methods.1

Put simply, as disposable incomes rise around the globe, we simply can’t meet the demand for meat — and leather consumer goods — using resources available on the planet.

Mylo is also produced in days versus years, without the material waste of using animal hides.

Mylo is also a more sustainable option than synthetic leathers, most of which are made from polyurethane or PVC, These so-called ‘pleathers’ are manufactured using numerous toxic chemicals. While not proven to be dangerous to humans during use, these toxic chemistries persist in the landfills and groundwater where they end up.

Because Mylo™ is made from organic matter, it is completely biodegradable and non-toxic. (Note: animal hide is also biodegradable.)

We will undertake a full lifecycle analysis of Mylo™ prior to large scale commercial rollout, and we look forward to sharing those findings with the world.
1 Source: Livestock’s Long Shadow: Environmental Issues and Options, a 2006 report published by the United Nations Food and Agriculture Organization

Bolt Threads
5858 Horton St, Suite 400
Emeryville, CA 94608

(415) 325-5912
Disclaimer: We know learning about the potential biomaterials can inspire a wealth of ideas and we love your creativity. Before you send us your awesome ideas, please know that we don't want to accidentally come up with an idea similar to yours, so any concept you email us will become the property of Bolt Threads Inc.

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