Bolt Threads (Mylo)

overall rating:



Harper Kiger Eaton
No items found.

Bolt Threads has an important role to play in the progression away from petroleum-based products. Inspired by nature and biomimicry, Bolt has created very innovative products like B-silk, Microsilk, and Mylo. Mylo is a material made from Mycelium, the web-like threads that grow under fungi, providing an alternative to leather. Bolt is a relatively young company and Mylo products are set to be released in 2022. Because of this, there is limited information about their actual carbon footprint. Mylo has the potential to become a very effective sustainable material and Bolt should be commended for its innovation. However, I hope to see more transparency in the future when they release their Life Cycle Assessment in 2022. I gave Mylo an overall score of 1.75 planets because they aim to help negate the most impactful actions arising from leather production such as deforestation, GHG emissions, and extensive water use. However, they have not been able to remove all plastics from their production and lack some transparency. As of right now, they are helping the world by creating alternatives but they are yet to find all of the answers. This is very understandable given the age of the company.

What it's made of:


Bolt Threads is a company designed around biomimicry. Their design process tries to replicate natural processes within our environment. Trying to replicate nature has ultimately led them to design natural materials. Mylo is a patented unleather designed using mycelium, the fibers that are grown underneath fungi. They define unleather as “the radical act of choosing products made sustainably with infinitely renewable mycelium over animal and synthetic-based materials.” Commercial leather production is a very water and chemical-intensive process that can have detrimental impacts on the environment. With Mylo, Bolt Threads is trying to eliminate some of these negative environmental impacts while integrating a very promising new material. It should be said that Bolt Threads is a small company that has not yet scaled its business. Most of their Mylo products will be launched in 2022 with partners like Adidas, Lululemon, and Stella McCartney. They have done a preliminary life cycle assessment (LCA) but a full LCA will be released in 2022. This is quite reasonable because of their size, however, in the future it is important that this information is made readily available to its consumers.

Bolt Threads has a very interesting product that could help reshape the fashion industry. It is a promising diversion from old practices that are unsustainable and an important step towards a sustainable future. It must be said that their products are not completely sustainable. While I was scrolling through the pages of their website my eyes were constantly coming across bold sustainability-related claims. However, after reading through the fine print it became apparent that these claims were slightly misleading. For example, they claim their products are more sustainable than synthetic leather. They assert that they do not use petroleum-based products like polyurethane and PVC coating that are used in synthetic leather. When you read the finer print, however, you can see that Mylo’s unleather still incorporates some plastics. While Mylo is certified bio-based, this means that only 50-80% of the materials incorporated are renewable ingredients found in nature, not 100% as we may hope. Their materials were selected with Green Chemistry standards and they exclude the two most harmful chemicals, chromium and DMF, from dyeing procedures. Rather than listing the materials they use, their website lists the materials that are not used. Despite this, it is certain that products derived from mycelium are more sustainable than synthetic and traditional leather. As a company, they are aiming to be 100% sustainable. They are making great strides towards this goal and should be recognized for

How it's made:


The production of Mylo is where we can find the most sustainable advantages compared to traditional and synthetic leather. In the making of traditional leather, you need huge areas of land for animals to graze. Raising livestock contributes to a disproportionate amount of worldwide deforestation. Tending this land and feeding the animals is water and resource-intensive. Additionally, livestock like cattle emit massive amounts of greenhouse gasses, whereas a product like Mylo eliminates almost all of these negative impacts. The main ingredient in Mylo unleather is mycelium. Mycelium is the web-like network of fungal threads that grow underneath fungi. Mycelium cells are fed sawdust and other organic materials while their esteemed scientists control humidity to maximize growth. After one to two weeks, the mycelium is harvested, and the other parts of the fungi and mycelium that are not used are composted. Bolt grows their mycelium in indoor labs in California that are 100% powered with renewable energy. There is no need to cut down chunks of forests to produce the mycelium. Instead, they are able to maximize the efficiency of their space by growing fungi vertically. We do not yet have access to the carbon footprint of their growing facilities but we can assume that because they are able to grow in-house with renewable energy this footprint would be relatively low.

The actual production of mycelium is a great example of a renewable substitute. They have found a relatively clean solution to leather. However, I do have some outstanding questions about the dyeing of their materials. There is little information about where and how their products are dyed. On they say: “we have partnered with world experts in tanning and dyeing who have been recognized with global sustainability certifications to help build a process designed for human health and safety and the lowest environmental impact.” This is great, but as a consumer, I want to know more. I have no reason to assume this information is false or misleading as Bolt has clearly made great strides in number of key areas, however, I do expect to see either data on, or descriptions, of these processes. The only concrete fact we know about their dyeing process is that they do not use harmful chemicals chromium and DMF. The largest benefit that I have seen from Mylo products is that they are a great alternative to unsustainable solutions. With information lacking on their supply chain and production processes, it is hard to say how sustainable they truly are.

Who makes it:


It is clear that Bolt does not aim for positive environmental change at the expense of positive social change. Making sustainable materials indirectly benefits society as a whole. When scrolling through the website you see many statements like “designed for the future” or “developing the next generation”. Statements like these show the company’s true values. Based on my own research, I do believe that Bolt is here to create new alternatives that can help our future. While some of the details are unclear, I do not believe this is an attempt at greenwashing. Some of the little information we do have concerns their corporate responsibility team. The current director of corporate responsibility, Libby Sommer, has translated her experience in the Environmental Protection Agency to consumer brands like Nike and Lululemon. After working with the EPA, she realized the important role consumer brands have within sustainability. Hiring people like Libby, a professional with a lot of relevant experience should make you feel good that they are headed in the right direction.

I would like to see more information from Bolt about how they treat and interact with their employees. Right now there is very limited information about this. The one action that I have found that illustrates their commitment to their employees was the elimination of toxic chemicals. Bolt commits most of their time to reimagining engineering. They realized that lots of dyeing techniques used chemicals that led to various negative impacts on the environment. Bolt found that when they removed chemicals like chromium and DMF, they were still able to make products with the same standards. When they removed these chemicals, they were able to ensure the health and wellbeing of their employees by eliminating exposure to toxic chemicals. In general, I would like to see more specific initiatives that help their employees.