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Mylo: A leather-like material made from mycelium (boltthreads.com)
574 points by tuanx5 10 months ago | hide | past | web | favorite | 160 comments

Coincidentally, a friend recently showed me his "mushroom hat", which is made from "amadou": https://en.wikipedia.org/wiki/Amadou. It's a wonderful lightweight texture, somewhere between leather and felt. A description of the manufacturing process (and the mushroom which it comes from) is here: http://frimminjimbits.blogspot.com/2012/08/mushroom-cap.html

Obligatory picture of Paul wearing his mushroom hat? Check.

The picture of “Paul” is Paul Stamets, The Godfather of Fungus.

> The picture of “Paul” is Paul Stamets, The Godfather of Fungus.

Huh -- I guess that's the source of the name of the engineer on Star Trek: Discovery (also Paul Stamets). He works with the "mycelial network."

Yup. He gets into it on JRE: https://www.youtube.com/watch?v=mPqWstVnRjQ

Amazing podcast. Well worth a listen.

Yep. I believe I read that the real Paul Stamets is an advisor for the show, too.

Well, I think "advisor" is probably more like it, because it does the science of mycology quite the disservice. Beyond playing fast and loose with the science for the sake of the story, there are basic mistakes that I doubt that the real Paul Stamets would have let slip through.

I wouldn't be surprised if the HN crowd is a bit hostile to FeministFrequency, but if you can skip over that you may enjoy this guest-podcast (meaning none of the FF regulars have anything to do with this particular podcast episode) by Emily Taylor, a mycologist-turned-game designer, where she explains all of the mycology-related issues of the show:


Why would the HN crowd be hostile towards FeministFrequency?

I should have said "significant sub-section", not implied HN as a whole.

I don't think it's controversial to say that the Ven diagrams of start-up loving nerds, and the type of entitled young men who have an axe to grind with FF are likely to have a non-empty intersection.

Anyone else catch him on Joe Rogan? He got real weird at one point and said he couldn't talk about a topic because it would put his life in danger

Yes! It was a good podcast but got incredibly weird at that point. I took him as not a bullshitter so it's either true and something amazing must be being covered up or perhaps he got the wrong end of the stick somehow.

It certainly was a weird part of the otherwise fascinating podcast.

I did a bit of digging after the show, he said that it would be "an explosive issue" or something- but the way he emphasized "explosive" made me think it was a hint- and so it was.

Turns out portobello mushrooms contain a decently large amount of agaritine, which can be made in to hydrazine, which can in turn be used for explosives or rocket fuel. Agaritine is also fairly cancerous/mutagenic to humans.

That's my best bet as to why he wouldn't talk about it, though the threat to his life I would think is more for comic effect.

Agreed, that has to be it. Apparently there is some sort of law suit or something going on about the cancer causing properties.

Yes! I did the very same thing and came to that same conclusion.

Wouldn't it be extremely flammable though? Raw amadou can burn even with the smallest spark. We used to make lighters out of it.

I've never used that particular mushroom before, but you can use polyporous mushrooms as tinder if you find them in the wilderness.

The flammability is measured by the fact that they burn very slowly, like charcoals. On the flip side, they easily take sparks and aren't necessarily obvious that they're burning until they start getting pretty hot. While this makes them ideal for lighting fires with in damp areas, I would think it makes them a poor choice for headwear -- though of course cotton and felt hats take to flame pretty easily too.


Paul Stamets has one, and says he's only seen it smolder when someone lit a joint near it.

This was my first thought. They must have some built in fire retardant layer. Otherwise you a cigarette burn would set you alight. Interesting point, I'm not sure how fast it burns. It might just smolder away. Still not desirable!

It's slow and not very "flammy", so it wouldn't turn you into a torch.

that hat is amazing!

Leather production comes at a very high cost to the environment. So I welcome any real alternative (assuming it is significantly less dirty).


A couple of years ago I came across Tjeerd Veenhoven's palm leather[0][1]. It is probably not quite as super-durable as pure leather, but still quite incredible given how simple it is to produce (basically, soak a palm leaf husk in a water/glycerine solution for a few days), and given that it is mainly made from what used to be waste materials.

Sadly it seems the products based on it did take off enough for it to become a thing (especially since he seemed to be doing his best to also ensure the local economy of the places where this material would be produced would benefit from it). The project got turned into a foundation that tries to support a local economy and design community, so who knows, it might make a comeback in a few years[2].

More recently Veenhoven has been developing pigments from discarded tulip flower heads[3], and fabrics based on algae[4].

[0] http://www.tjeerdveenhoven.com/portfolio_page/palm-leather/

[1] https://www.youtube.com/watch?v=Xo7Zfw8eLso

[2] http://www.tjeerdveenhoven.com/portfolio_page/wishful-doing-...

[3] http://www.tjeerdveenhoven.com/portfolio_page/tulip-pigments...

[4] http://www.tjeerdveenhoven.com/portfolio_page/algaefabrics/

Won't that leather still get used elsewhere? I don't think many animals are reared with the primarry intent of producing leather but rather becouse of our high meat demand and we can't make one without the other.

Then we should start consuming them. Javanese & Minangkabau people of Indonesia does.

Prepared properly, they have jelly-like texture and taste earthy. Great in soup and spicy dishes.

Fresh from farm: https://imgur.com/05LFWnq

Final product before cooking: https://imgur.com/tqICpVR

Or stop eating meat. Probably a better choice.

It will be interesting to see what happens over the next decade or two, once synthmeat is good enough to take over the market. Various breeds of cattle will likely go extinct, and the same social opprobrium that will wipe out the market for "real" meat will presumably affect leather goods as well.

When synthetic meat becomes good enough there'll still be loads of people who'll say it's inferior to the real thing. Apart from that I believe a happy cow is better than no cow so sustainable and environmentally-friendly livestock farms still have a reason to exist.

Well, already you have "loads of people" claiming that kobe beef is better than regular beef (or that the black iberian pig is better than other kinds of pig). Yet, since meet from those animals is expensive, in practice the vast majority of meat doesn't come from these species.

It can be identical with synthetic vs natural meat. Price can make the difference, and we can still reduce massively the amount of livestock we breed (e.g. make the farms more environmentally-friendly through regulation)

>"Well, already you have "loads of people" claiming that kobe beef is better than regular beef (or that the black iberian pig is better than other kinds of pig). Yet, since meet from those animals is expensive, in practice the vast majority of meat doesn't come from these species.

Having just been on vacation in Malaga (highly recommended), Jamon Iberico Bellota -- the highest-quality ham from acorn-fed black iberian pigs -- is absolutely, genuinely so superior to lesser hams that it's not even funny. There is just no comparison.

It also costs at least €130/kg even the smallest local ham stores, so yes it is prohibitively expensive, you can expect to pay at least twice that for the genuine stuff, if you're not in Andalusia.

How much of the taste is because the diet, and how much is because of the breed? Who knows, but I think it's a combination.

> how much is because of the breed

The genetics of the "iberian black pig" are different in a surpsiging way. Studies have shown that their meet contains a lot more monounsaturated fats (The good oil, like olive oil) than other pigs. When raised on acorn and free-roaming, their bodies carry out more endogenous lipolysis. So it's considered a healthy meat to consume (and is raised sustainably to boot).

[0] https://www.uco.es/dptos/prod-animal/economia/dehesa/salud.h... [1] http://www.mdpi.com/1422-0067/19/1/22/pdf

It is and there are official classifications for that. Ibérico is about the race, pata negra (black paw) being a best subclass name that expanded to anything first class. If a Spaniard says you are pata negra, it's actually good, not an indictment on your feet higiene :)

Bellota (acorn) the diet. You can find intermediate categories like "50% raza ibérica" or "recebo" for both.

Oh yes, I got a very thorough explanation and examples from a very dedicated ham shop owner. It was a bit of a lazy afternoon, so he took the time to properly school us on every detail and the classification system.

If you're ever in Malaga, hit up Azabache in the old part of town. One hell of a shop for ham and cheese and a bit of seafood.

Kobe beef doesn't really affect the consumption of other beef in a material way not just because it's much more expensive, but (probably mainly) because it's available in very limited quantities and all but impossible to obtain in most parts of the world. Its supply is simply too limited to affect demand for other meats in any appreciable way.

Not that I necessarily disagree with your overall point, though.

Living in Spain, the ham does taste a lot better from black Iberian pigs.

> I believe a happy cow is better than no cow

Considering that most of US beef comes from factory farms, the concept of the "happy cow" is nearly mythological. Given the choice, I would rather not exist than play those odds.

Totally agree! There are no happy cows in farming. btw the cows that are killed for meat are babies, killed well before their natural lifespan.

unfortunately a lot of cows are raised and killed just for leather! (I think for high end uses like purses, etc.). I don't have an a source for this handy but have heard it from industry experts.

Still needs to be tanned and dyed. With the same products. As a lot of the problem with the leather is that tanning products and inks are poisonous, IMHO probably is not a solution for this problem. Mycelium is more porous than leather (probably), so it could absorb more product.

But I could be wrong. Just speculating. Better than plastic for sure if enough strong and can be certified non-allergenig or a cause of asthma.

A lot of the benefit hopefully comes from reducing the carbon footprint that would have gone into a cow.

That cow will still be raised unless the higher cost of the meat (via a lower demand for leather due to mycelium) drives down demand (for meat).

For now. But it removes yet another barrier to consume less cows. Humanity solves problems step by step. It's ok if it takes a century.

I don’t think we have a century to solve the problem with greenhouse gases.

A lot of the problem with the leather is that you have to kill cows, lambs, etc. for fashion.

But on the plus side a leather jacket can last a lifetime. And they cost mid-hundreds to low-thousands for a decent one so people aren’t buying as many of them as they would a $15 plastic / polyester throwaway jacket from wal mart.

Presumably we're killing the cows and lambs for fashion AND food? Even if we stopped using animal leather materials tomorrow, I doubt it would put much of a dent in the industry.

(For the record I'm all for eating meat, but I agree that beef is unsustainably bad for the environment compared to other animal options like poultry and eggs.)

But leather subsidises the cost of raising animals for meat so reduced demand for it should raise the price of beef. Ideally that would encourage people to eat less beef, and eat more sustainable meats (or no meat at all).

If livestock ranchers cannot sell the skins as leather, they can sell them as cracklings. Or as parchment. Or as gelatin. Or as pet food. Or as fertilizer.

As long as the demand for some product causes the animal to be raised, the undesirable parts will become by-products.

A competitor for leather would depress the price of animal leather, which would tend to raise the price of meat, probably disproportionately for the best cuts. Forelegs, brains, and chitterlings would go up a few cents a pound, while tongues and tenderloins would go up by dollars per pound.

That might encourage people to eat less meat, but it might also encourage them to substitute the cheaper cuts of meat--which include the skins. Rawhide soup, anyone?

It wouldn't put a dent in the industry at all. We raise and kill cows for their meat, not their skins. Their skins are just a handy byproduct. Eliminating the cow-leather market won't change that at all; it might make beef slightly more expensive (I imagine most of the cost of leather is in the processing, not the raw hide), but that's not going to affect beef consumption.

If we mostly eliminate beef (in favor of artificially-grown beef, for instance, which might be a reality in 10-20 years), that'll make cowhides much, much more expensive, so people simply won't be getting leather car seats, leather coats, etc., except maybe for extremely high-end markets.

Putting personal preference (taste, price, etc.) aside, I'm curious what other reasoning is behind your position of being "all for eating meat" (if any)?

I'm assuming here that by mentioning it in the same sentence as you say beef is bad for the environment, you are talking about being for meat production on a global scale, and not just for your personal preference.

yes I too would like to know the reason for being "all for eating meat". I think most reasonable people wouldn't eat meat (provided reasonable food alternatives) if they got to know the animals and how much they suffer. (just like most Americans would refuse to eat dogs or cats)

> ... the problem is that we have to kill cows for fashion

This is a false problem.

Clothes are more than fashion. Leather extracted from dead animals is a big ally against animal cruelty and I'm not trolling. Lets remember why we use it. It saves millions of worker humans from having horrible injuries, painful deep cuts and mutilations.

Could workers rely equally in mycelium for not losing a finger or a leg by a saw if they stumble?

Is mycelium flammable? When I'm using an arc welding torch I want to wear a solid >1mm leather apron. If something goes wrong, leather will save my arms and body from a severe burning. Can filosophy or whisful thinking do the same for me?.

I would not hire a vegan worker if they stubbornly refuse to wear protective clothes arguing that we have pleather that "looks the same" (and burns like gasoline). Would be really irresponsible on my part to hire them.

> on the plus side a leather jacket can last a lifetime, vs polyester throwaway...

100% agree with this

Firemen haven't worn leather as primary protection for a very long time. In fact, I wear a fireman's Kevlar turnout when I weld.

I wear leather gloves, but wouldn't hesitate to use a knitted Kevlar alternative, especially since it would insulate much better.

I'm not very familiar with non-leather options for welding, but looking around I see fire proofed cotton and kevlar based garments as alternatives. Would you not be willing to hire a vegan welder if they provided their own protective gear that wasn't leather?

Here are some options I've seen but I really have no idea if they're good enough:

* https://www.amazon.com/Ironclad-HW6X-04-L-Heatworx-Heavy-Glo...

* https://www.amazon.com/ThxToms-932%C2%B0F-Resistant-Kevlar-G...

* https://apparelsolutionsinternational.com/products/fr-covera...

To me, the question is not whether the alternatives would be as good as leather but would be a good enough alternative to leather.

I wear Kevlar, but I'll note one great advantage to leather: it abrades and tears somewhat like skin and doesn't really catch like woven Kevlar can. If you're welding, you're likely also in the vicinity of spinning things, like cutting and grinding disks.

Obviously, it all comes down to balancing needs and risks. I just thought I'd point out how you can meet or exceed one requirement (flameproofing) but potentially create a new risk in the process.

> Would you not be willing to hire a vegan welder if they provided their own protective gear that wasn't leather?

It depends of what she/he consider protective gear. Kevlar is fine. Anything that is regulated, lawful, well tested, reliable and covered by the assurance is fine. Those new materials can't still be trusted at the same level and you don't want to be the first to discover in your company that they are acid permeable or burn like a torch when react with some chemical

To let some of your employees work with a lower protection against accidents than other employees, would be negligent and easily prosecutable in court. The non-vegane parents of a vegane killed in an accident would not doubt a second to sue you in this case.

Reported feb 2017, with shutdown of the district ("no exceptions") slated for mar 31, 2017. So what happened, did it shut down and move to the new park that has waste treatment, etc?

I came across fish leather at a market recently. It is very durable and interesting in appearance. I don't know that it is cheaper or less dirty, but it could be. http://thefishleather.co

Is dirty in its own way, but more sustainable for sure.


the alternatives will probably be more dirty when you factor in energy, waste, non-biodegradable plastics, etc.

"dirty" isn't really well-orderable. It depends on what you're worried about. Chromium toxicity is definitely a huge problem with current leather production, as well as atmospheric effects and water use from raising cattle.

"It’s strong, and abrasion resistant." As a motorcyclist, I need to see a side-by-side abrasion resistance comparison. So far, nothing beats leather.

technically toilet paper is "strong, abrasion resistant".

But since they did not mention durability anywhere on the marketing speak, that means even their marketeer couldn't find a way to lie about durability qualities. Unfortunately nothing to see here :(

Also read between the lines about biodegradability - I'm betting this stuff breaks down relatively quickly?

Like leather. We treat leather.

I was going to make a similar post. I'd love a green alternative but so far I haven't found anything that performs or looks as good as genuine leather motorcycle jacket.

Yeah they didn’t really address that anywhere. I’m thinking it will be ok for fashion but not ppe.

Leather is still superior for high speed slides. Something about its ability to stretch and conform slightly to the road surface, I believe. It doesn't really matter for road riding, but for racing, leather is still the way to go.

Can somebody explain how this is different to the "pleather" being made as a side-product from the production of Kombucha? Thats been a thing for a while now.

AFAIK its also grown by mould, from culture. But, it forms as a mat on top of the Kombucha fermenting liquid.

Here is what they say about pleather in their Sustainability section:

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.

Reading elsewhere, it doesn't look like Kombucha is a pleather. If not, then they are different processes for creating different materials that are substitutes for leather.

maybe they wrote pleather meaning faux leather instead of plastic leather

Yes. I did. Didn't realize it was a trademark

The kombucha byproduct looks like a vastly different material. The only real difference is that they're both kinda-sorta lather facsimiles?


(please help me where I'm wrong other scientists... But here's my basic knowledge.)

Leather as you know it are combinations a few different (known) structural proteins secreted from mammals between skin cells, after the skin cells themselves have been removed, and the proteins become chemically glued together (cross-linked). The majority of that protein is collagen.

Plether is a plastic fiber (petroleum derivative) that is spun and processed in such a way as to have an appearance similar to the final leather product (kind of, close enough). It's not protein-based in any way.

This new leather, 'Mylo', is a protein-based 'fabric' where the base protein is secreted by fungi rather than mammals. However, fungi are similar enough to mammals evolutionarily, that the proteins they secrete are evolutionary related to those secreted by our own cells to make our skin. The primary protein in both cases is collagen. Additionally, fungi genetics are easily manipulable, so you can actually insert the DNA that encodes for mammal-like collagen, other proteins found in animal leather, or proteins with new or completely different functions that would never show up on the skin of a mammal (color, water resistance, enzymatic capabilities, etc.).

tldr: Pleather is nothing like animal leather chemically - but has some similar bulk properties. This new MyLo is chemically related (evolutionarily) to animal leather, but ultimately comes from fungi. But because it's genetically known, it can actually include new capabilities that cannot be found in animal leather.

Yes, like us, fungi are opisthokonts, but where collagen is the mammalian structural protein used for making leather, fungal hyphae are principally comprised of chitin—structurally closer to the polysaccharide cellulose of the mentioned "kombucha leather" than to the collagen protein. Collagen is present in fungi in certain edge cases, but bulk mycelium is mostly chitin. This is speculation, but leather made from chitin may actually be a bit stronger than animal leather made from collagen. Maybe closer to keratin in strength? (Interestingly, keratin is chemically cleaved in hides during leather production--not entirely sure why, to enhance flexibility and allow access to the collagen fibers?). Agreed about fungi being easier to engineer. As you point out, endogenous expression of dyes in hyphae for different colors of mycelial leather is compelling. GFP would be cool too for the rave and nightclub crowd.

The Quorn meat analogue[1] is another product made from compressed mycelium. I've had "chicken" nuggets made from it. They're...not bad, but as far as mycelial structures go I prefer mushrooms.

1. http://www.misac.org.uk/PDFs/MiSAC_Briefings_1.pdf

Nicely put. They do state in the FAQ that currently don't use genetically modified fungi, though it's a nice bonus that could be used in the future.

It’s a funky creature called a SCOBY, which is pretty much what it says on the tin, “Symbiotic Culture of Bacteria and Yeast.”

A bit of a missed opportunity there. I would have looked for a change to slip an extra 'O' in there ('organic' perhaps?) to get SCOOBY.

I'm curious to know how well this new material handles exposure to humidity/water, as I've grown some of the kombucha leather and its durability seemed to go out the window once it becomes wet (and possibly is exposed to significant humidity).

I believe they licensed the mycelium technology from a NY based startup called Ecovative, that has been shopping it around for furniture for some time.


Proof: website: https://www.ecovativedesign.com/

The problem with pleather, in my experience, isn't that it feels insufficiently leather-like. The appearance is also just fine; the tendency to fade actually produces a somewhat nice pattern. The real problem is that the durability of most fake leather is drastically inferior to natural leather.

From personal experience, I had a leather jacket which I got in my first year of college (2008) and wore until it was stolen from my car in early 2016, when it was still in nearly-perfect condition (although the zipper got worse). I replaced it with a pleather jacket which has already lost most of the material on the right elbow and may soon develop a hole.

So I hope this mushroom-derived material will be at least somewhat more durable. What I really want to see is a sort of fake leather made from a more resilient polymer, such as polyetherimide or one of the other "high-performance polymers". Until that situation improves, I think I'm going back to cowhide.

I still wear the leather motorcycle jacket I bought when I moved to Seattle in 1999. (I didn't even own a motorcycle then; I just bought it because it looked cool!) I've had to replace snaps and zipper pulls, but even after years of abuse, including half a dozen unintended close encounters with asphalt, the leather is still holding up fine.

the durability of most fake leather is drastically inferior to natural leather

How about Corfam? It was promoted as 'wearing like iron.'

Remember the song from "Oklahoma" about the "Surrey with the Fringe on the Top"? It says, "The dashboard's genuine leather." So what was artificial leather in 1905 Oklahoma? Something like cardboard with wax-paper veneered on, IIRC. Is Mylo better than that?Geniuses been trying a long time to do this. Even money that we'll have tomatoes with leather skins or cows that are born with 'Wilson' on their sides so footballs are easier to make before anything exists that is a better leather than leather.

The durability isn't just a nice feature, but for motorcyclists is essential. I haven't found anything that comes close to the abrasion resistance that natural leather has (while looking like a leather jacket, not including things like kevlar for example).

Top it off with durability that can seriously last a lifetime and look better with age, there's no real competition in the synthetic leathers that comes close to the real thing.

I'm not a motorcyclist, and I noticed multiple comments mentioning durability of leather is important for motorcyclists. How come? Is falling off a common thing with motorcycles? It sure isn't very common with bicycles or cars.

I don’t think it’s about how often. It’s about that one time it happens, you want protection. The skid distance on a motorcycle isn’t comparable to a bicycle.

It's not that accidents happen often, it's that they will happen given enough time, and when they do happen you really want to be protected. Even quality thick selvedge denim jeans tear like wet tissue paper in under a second when you slide on pavement. Leather has been long proven to have great abrasion resistance saving yourself from needing a skin graft in the unfortunate event of a slide (which will happen at least once in any motorcyclists career).

I just really wish there was a faux-leather option that looked and performed as well as a real-leather jacket.

I wouldn't say it's common, but it does happen. A skid in a car due to something like an oil spill in a corner would be a lowside on a bike, and a bit of a slide. With reasonable gear (leather or high-quality textile, with shock-absorbing pads), it's relatively undramatic, but rather annoying.

It's just the nature of 2-wheeled vehicles of all kinds.

Interesting, although on the business side, what happened to the spider silk? Bolt closed a $125m round in November 2017. You only get that kind of money if you are a messianic founder or have lots of progress.... This feels like this is some kind of auxiliary parachute. I wonder if the investors knew. Ironic that Peter Theil’s Founders Fund was one of the investors.... “We wanted spider silk and instead we got mushroom leather.”

They have a separate section on their website describing their Microsilk, which is being used to produce ties.

https://boltthreads.com/technology/microsilk/ https://ties.boltthreads.com/

This is just speculation, but this looks to be in a “coming soon” state. They could be having any number of issues, including scaling, cost reduction, and the macro properties of the fabric may not have lived up to the early promises.

This is exciting for new leather products, I'd like to see how a pair of boxing gloves or a pair of Thai pads made from such a material hold up. As for other leather goods. I usually just buy them second hand from a goodwill or something. Almost, Second-hand anything is good for the environment.

Second hand leather is better for the environment that this product, that is a fact.

that's what I was trying to communicate! :)

Very fun. A number of new players here. I look forward to the more exotic possibilities downstream. Integrating other biological capabilities, relaxing size, thickness, supplychain constraints, being part of a genetically-dynamic R&D process.

I'm curious about the different approaches between Bolt (who've so far at least been focused on fermentation) and Modern Meadow - versus newer smaller players like Provenance.



Is it absolutely necessary to always write (tm) after every Mylo? It's so distracting. And, well, corporate. It's gross.

How do we get to a world where we can stop doing that? Or do we already live in one and not everybody knows?

They're asserting their trademark, using TM is legally impotent in the UK. Trademarks are trademarks, their legal status changes with registration when you get to use RTM.

Don't know if it works in other countries I assume it's different in USA, maybe affects damages?

Funny thing I am not sure what fungus it is. However, I have pulled small sheets of material that is almost like leather out from beneath the bark on firewood when splitting it. It's very white kinda soft too.

I wonder if this is the same thing, and then they just dye it.

-Edit- It usually looks like this, but sometimes grows into like a sheet between the bark, and wood. https://projects.ncsu.edu/cals/course/pp728/Armillaria/fans....

Cool product, it just bothers me that they describe mycelium as the "underground root structure of mushrooms". That's like saying the rest of a plant is just part of a flower.

Yep. The truth is, mushrooms are really just the sex organs of mycelium.

More accurately, "Fruiting bodies".

I found the conversation between Paul Stamets and Joe Rogan to be super interesting: https://www.youtube.com/watch?v=mPqWstVnRjQ . Never really thought much about mushrooms until that episode. This proof of concept seems like a great taste of how much untapped potential fungi have for changing everyday life if we invest more into its research.

Keep in mind, this only obviates one of the "sustainable" aspects of leather production, the raw untanned hides. From an environmental perspective its chrome tanning and dyeing that are the big hitters, and that would still be necessary here. They could veg tan it instead, but that only slightly lessens the environmental impact at significantly higher cost.

Would this be a good candidate to use as a synthetic skin for touch-able robots and devices? I've thought for awhile that leather might be good for that, but something like this which could be grown with electronics, heating elements, and other things embedded directly into it would probably be much better!

It's very inelastic. Good skin will probably need to stretch reasonably well.

don't forget about lubrication

Perhaps a silly question, but what does it smell like?

Exactly what I wondered as well.

This is incredibly exciting from an environmental standpoint alone, let alone the implications for future materials research. I'm curious about the processing steps required to create the end product and the resulting durability.

Simple question that they didn't answer anywhere: how long until your mylo jacket degrades into mushroom goo?

"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."

I'm assuming this also means finding out how long 'til it disintegrates.

In their FAQ, I think they should address the question, "Is it possible that mold will grow from Mylo?" I'm sure the answer is no, but they should state it explicitly.

Considering it's still tanned the same way, that process will probably preserve it and prevent mold growth, just as with leather.

Very cool, but really wonder what the durability is. Is it more like faux leather which might be used as an accent or is it something you could actually use structurally.

This seems to be another application of the organism used for the meat-substitute sold under the brand https://en.m.wikipedia.org/wiki/Quorn. (Which is rather tasty when prepared right).

One thing I do not get about leather is why do people like it?

One sibling comment mention durability. But otherwise I find it's very heavy, cold, not breathable, sensitive to water and doesn't really look that well.

Sure I do prefer suede office shoes over normal leather, but that's about it. There are probably some good industrial use cases, but I much prefer Gore-tex type of materials and especially Merino wool. It's breathable, doesn't attract smell, somewhat water resistant, doesn't hurt animals too much and is close to cotton. I am rarely into clothing brands, but Icebreaker and Allbirds are making really good stuff that I've been wearing non-stop for years now.

Looks is an opinion but at least it ages better than most materials. Old leather belts or watchstraps look fine after many years of use.

It's awesome to see some more players in this space. I've been keenly watching out for Modern Meadow's updates as well. Looking forward to seeing what this will bring!

I wish one of their FAQ down the bottom was about water resistance.

There's probably a good reason they didn't mention that, or durability.

I do some leatherwork for fun and there's a lot of things that make it hard to replace. We'll see how it holds up when stitched.

I'm very open to trying it out, though. And maybe an upholstery waterproofer would do the job.

The fun part here is that, technically, once they get a 'good enough' product and workflow up and running, adding/changing/incorporating biological properties is (mostly) just a DNA-based bit-flip away.

We at Serotiny are already collecting protein domains from organisms with various capabilities - including water solubility, hydrophobicity, enzymatic capabilities, covalent attachment sites (for dyes), light-activated properties/crosslinking/dissociation/etc. And all of those protein domains we're collecting should be 100% compatible (+/- a fair bit of a tooling-exercise) with both Bolt's leather and their silk.

So it should get fun once they have a solid and stable 'platform' up and running. They will be able to incorporate most any property from nature with an existing proof of principal, not just any property form mammalian hides.

Congratulations guys!

As someone who does a fair bit of sewing I have to wonder if this is going to behave more like a "fabric" with leather like qualities.

From the description (and it isn't much) I'm guessing that this is going to drape much like felt. Is that close to leather? Well it is closer than most woven fabrics but leather and felt behave much differently.

I would also expect that this is going to cost far more than actual leather does.

I certainly wouldn't mind my next metal battle vest out of mycelium leather, just for the geek cred, deck it out with hardwood studs and do an enviro theme thing.

Well leather isn't really water resistant to begin with: ask any biker. It'll hold up to a light rain, but anything more you shouldn't expose leather to unless it's been waxed relatively recently. And once it is wet, if you dry it too quickly (like on a radiator) it'll likely shrivel up permanently, dry it too slow and it might rot.

Really the bar is set quite low for fake leather being waterproof.

Most hot-stuffed pull-up leathers are water resistant because of the incredible amount of waxes and oils added. Pull-up leather is often used in boots and duffels for that reason. Veg tan leathers can be made water resistent with Resolene or a TON of surfaces waxes like Carnauba.

Source: I work with a lot of leather.

I suppose I didn't consider the amount of additives in current leathers. What are the production costs (environmental, rather than monetary) of the waterproofing? It would be a shame to have something that has very limited impact on the environment being used as a substitute for leather, only to find out the post processing is also quite damaging.

Congrats! This looks like a home run.

Would love to see micrographs of the finished materials. Fungi possess wonderfully dense cobweb-like fibres. A terrific example of highly connected random graphs in nature!


With lab grown meat on the horizon as a main stream consumer product, it's only natural to wonder whether we could also grow lab grown skin to create synthetic leather.

Perhaps that defeats the purpose of mushroom based "leather" though? You might be able to grow the skin artificially, but it will still need to be tanned at an environmental cost.

That all depends on which process will be cheaper and which material will have the most desirable properties. I certainly hope the competition fosters better products in the end.

Super interesting! However...

...my impression (not dispelled or even challenged by their marketing materials) is that we currently have effectively surplus hides as a side effect of raising animals for meat, milk, and other purposes.

So when they say:

> 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. 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.

That seems to be about 90% true (but irrelevant) and 10% questionable. Livestock are very expensive environmentally, and as the world gets richer we will certainly struggle to support the current meat-heavy western diet for billions more people. But that still means we're going to be producing an enormous torrent of hides (more now than today). Are we really going to struggle to find enough hides to meet global demand for leather good? Prices for raw inputs have been remarkably flat for the past ~20 years (https://fred.stlouisfed.org/series/WPU04190108).

Even from the perspective of minimising animal cruelty, leather from animals that would already be raised and killed for meat or because they were ending their useful life on a dairy farm isn't especially problematic.


> 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.

So it still needs to be cured and tanned. Which no doubt helps it be a great leather substitute, but much of the cost (monetary and environmental) of leather isn't the hides, it's the curing and tanning process, which can use some pretty harsh chemicals. Another reason to be skeptical that this is a huge improvement environmentally.

I also note there's no real discussion of price. If this process can turn out finished leather more cheaply than traditional methods, that's a big sign this is more efficient environmentally. If it can't (and the silence is interesting), it raises the question of whether this is actually worse for the environment. (Which wouldn't be that hard to imagine!)

In short: Totally cool! But so far it doesn't look like a "we're going to get rich while saving the planet" kind of thing, more like a "maybe some vegans will pay a premium for a really good fake leather jacket" kind of thing. Also good! But not as amazing as they try to make it sound.

Maybe it makes more sense to view this in concert with other similar efforts to address different uses of livestock? Like, to replace all the uses of a cow with synthetics, you need lab-grown meat and lab-grown milk and lab-grown leather, and ...

And there are startups addressing each of these, independently of one another.

Until we're at that point, though, we're going to keep growing cattle the old fashioned way, and that means leather to spare.

Sure, but it'd be a shame to reach that point on the meat front and then still have to keep growing cattle for the leather while the textile technologies catch up. Why not do both now?

Chances are you'd be growing a whole mix of cow parts at first and have to figure out how to differentiate them for the vats, so I doubt it'd be a problem. By the time vat meat works properly, you'd probably have the right knowledge and tech to grow cow hide by the mile simultaneously.

This is the future I want.

I've gone through the entire article and have taken a moment to check the links and it's amazing very organic and very astonishing nature has the hidden gems for us discover.


One of those things that feels completely obvious in retrospect yet I envy person that has the mind to think you can grow mushrooms and make leather out of it.

I'm curious as to how this handles high temperatures. Almost all welding gloves, aprons etc. that I have seen are made of leather due to this property.

Today: Leather; Tomorrow: Space travel!

How do they kill the fungus? I hope it won't continue growing if you wear it.

A lot of people have issues buying clothes that they outgrow a few years down the line. This is clearly the solution to expanding waistlines.

I've long joked we're going to create clothes out of fungus that lives off dead skin cells. And cure baldness the same way using Lichen that looks like luxurious hair.

that is super cool and hilarious.

It's tanned, so I'm betting it's quite dead.

If the cow doesn't, why would the fungus?

Random tiny fragments of cows don't cause cows growing around my house or on my stuff. Fungus/mold does that.

That sounds like a great science fiction story though!

A fungus is a much more distributed organism than a cow?

It's not that it has a throat to cut or a brain to kill.

self repairing clothes

I wish they were taking on investments; I want to sink some cash into them.

Two most important things that were left out are durability and price.

That was my immediate question, as leather is one of the most hard-wearing upholstery materials available. As far as price goes, at first blush I would imagine this would scale fairly well, at least much better than livestock.

Is it patented?

Allows you to travel at warp factor 13!

Tensile strength, tear resistance?

Interesting. But I cannot see any table with reference to mechanical properties of the new materials. MycoWorks instead shed some light upon it on their website. They are using strains of Ganoderma lucidim, and it can be tanned while it grows, not after.

I went down a rabbit hole, and stumbled upon http://www.mycoworks.com/ as well which is seemingly an earlier competitor. Particularly their resources & reading section at the bottom references a number of papers on the subject.

Insert obligatory Star Trek Discovery reference here.

Or Dune


Please don't turn HN into Reddit.

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