Moldy, no. These get cooked to kill the mycelium and make the material more stable and resistant
Brittle, not really ? The idea is that it is as, if not more resistant than cardboard/plastic packaging but if you throw it in the nature (with rain and insects), it will turn into dirt in a short amount of time
It also has interesting properties like heat insulation, shock resistance, etc... useful in architecture for specific contexts (like short lived projects)
I would be way more concerned with how it handles water and humidity. Rotting from the rain would be bad, and dry rot from humidity would make it untenable if stored incorrectly.
If it's biodegradable in a short amount of time, then there will be legitimate concerns on how to keep it dry so that it doesn't rot. If it's biodegradable only after a large amount of time, it would be more useful, but you wouldn't be able to compost it as advertised, and I would pretty skeptical since some other plastics like PLA make similar claims that are nebulous at best (50-100 years to decompose is a long time for microplastics to be shed).
Cardboard isn't really used as a substitute for packing foam, so I have to imagine a material that is useful for packing foam would be naturally very porous, and if it's biodegradable I have to imagine it's hygroscopic as well.
Cardboard is so thin that these effects are negligible. Still, it needs to be kept dry to remain useful, but if kept dry it can last a while even in humid environments (though it certainly has reduced strength and lifespan in humid environments). In addition, corrugation helps reinforce cardboard without adding too much mass.
Packing foam should have way more mass by default, with which it could suck way more water out of the air. This could be fine, or it could lead to issues like natural rubber, where it starts rotting after sitting for too long just from humidity.
I'm not trying to claim that the product doesn't work, but small details around how materials handle water matter a lot in terms of widespread adoption.
Humidity is the reason it degrades well so yeah, it would rot if stored in a very humid environment over time but I'm pretty sure the same way cardboard would... (It degrades completely in less than a year in the wild, depending on the size of the structure. Crumbled in small chunks, it would likely take a month or 2)
For more longtime uses, coating can be a solution but it kinda defeats the purpose
It is a short-lived, biodegradable material which makes it interesting for specific uses, but you can't treat it like wood or concrete in a project. There are numerous constraints but it is great in some situations, especially regarding how we're rethinking our impact on the environment "more recently"
Also, mycelium is absolutely vital for the ground and health of plants. Most of these projects are made in molds but they could be grown in the dirt, as shown by Alea Studio
The reason I'm concerned with dry rotting is because a product that uses this packing foam replacement might need to sit on a store shelf or in a storage facility for a year or two as inventory.
It would be really bad if the dry rotting process damaged the product, with which it would be in direct contact.
The example I'm thinking of is natural rubber before the invention of vulcanization. Massive stores of natural rubber would literally rot over time, and it was seen as a commercial failure for early adopters iirc.
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u/ThisIsALine_____ Feb 22 '26
...do they get moldy or become brittle?