Mycelium Composites

A composite is a material made from two or more individual materials. In a composite one material is the matrix or binder, and the other is the reinforcement. The matrices binds and holds the reinforcement into a single form. Some examples of a composite are concrete, plywood, paper-mache, and fiberglass. All wood is a naturally occurring composite of cellulose reinforcement held in a lignin matrix.

When mycelium grows on a material, it connects and binds that material into its network of nutrients. The mycelium absorbs nutrients from the material and connects the material into one biomass. Typically, mycelium is grown on dead plant matter, and binds that into a cork-like material. The material the mycelium is grown on is called a substrate.

Mycelium composites get a majority of its material properties from the substrate it’s grown on. Sawdust composites are denser, and has strong compressive strength. Cardboard composites are light, but rigid. By using different substrates, mycelium composites can vary in it’s uses and functions

In this image from Ilaria La Bianca, Wasabii Ng and Joost Vette “Building on Mycelium”, the effect of substrate on the composite’s structure, growth, and surface finish is clear. Within Mycopedia’s Test Index, structure, density, and surface finish are all tracked to show the wide array of possible new materials in the category of Mycelium composites.

By using two of Mycopedia’s tests, we can look at how different substrates lead to very different potential applications.

In this test, Blue Oyster mushrooms (pleurotus ostreatus), grown on the “Master’s Mix” of soybean hulls and sawdust, we can see dense and foamy mycelium growth. This test is considerably denser than other tests and has high compressive strength. We can imagine if the designer’s goal was to build structural objects, like furniture, how this composite could be used.

On the other hand, this test uses the same Blue Oyster mushrooms grown on cardboard. Lacking the nutrients of sawdust and soybean hulls, we can see that this mycelium has grown in to a wispy and light connector. This test is only marginally heavier than plain cardboard, but is now reinforced and held together by mycelium. It has inherited the cardboard’s rigidity, giving compressive strength in one direction. This composite’s materiality calls for different use cases, such as packaging or non-structural products.