The researchers at the Fraunhofer WKI, together with their partner Protohaus, are taking advantage of the fact that some fungi are capable of decomposing virtually all organic materials such as straw or sawdust. Mycelium is the term used to describe the totality of the thread-like cells of the fungus. During the decomposition of organic materials, the mycelium forms a three-dimensional network that results in a self-supporting structure. During the metabolic process, substrates – such as the elephant-grass fibers being hereby utilized – are permeated by the mycelium. This results in a soft, sponge-like and purely organic composite material that can be shaped into any desired form. “The mycelium has the function of a biologically grown adhesive, so to speak,” summarized Henrik-Alexander Christ, a scientist at the Fraunhofer WKI.

In this project, the desired form consisted of a mountain with cave entrances for the stage set of the play “Funken”. The Braunschweig State Theater is placing the participatory youth-theater play “Funken” by Till Wiebel at the center of its sustainability efforts. Emel Aydoğdu's directorial debut specifically addresses a young audience. The contemporary play revolves around the experiences of the thirteen-year-old protagonist Malte at summer camp. The mycelium is reflected as a central motif in the practical implementation of the project, but also at the content-related level: In nature, mycelia form networks, trees and fungi enter into symbioses, and the protagonist Malte also finds himself in the role of networker. At the same time, the play is intended to express the networking of the State Theater in the city and with cooperation partners such as the Fraunhofer WKI and Protohaus.

At the Fraunhofer WKI, researchers seized the opportunity to demonstrate the potential of building with mycelium. “Through the utilization of organic substrates, such as fibers from elephant grass, we are able to use residual materials to produce a 100 percent bio-based, degradable, renewable and low-energy building material. A variety of processes can be used to control and specifically create the desired properties and performance characteristics of the building material, such as texture, strength, elasticity and fiber orientation,” explained Dr. Steffen Sydow, a scientist at the Fraunhofer WKI.

The structure-giving elements inside the mountain are made from wood and were produced by the State Theater. For the surface of the mountain, the project partners at Protohaus added mycelium to the substrate of elephant-grass fibers and allowed it to grow through. In the Fraunhofer WKI technical center, the researchers used the wooden frames from the State Theater to create the shape and perform bonding and surface treatment. “We filled the frames with the material from Protohaus. We thereby aimed to reproduce a hilly structure. In this way, we succeeded in achieving a three-dimensional impression of a mountain. The frames were then treated in a climate chamber under high humidity. This produces a lovely smooth surface,” explained Mr. Christ. As a result of the subsequent drying process, the mycelium is inactivated and prevented from growing further.

The researchers also produced lampshades for the lights on stage, reported Dr. Sydow: “With the lampshades, we were able to showcase the expertise of the Fraunhofer WKI in yet another way: The mushroom-shaped shades consist of partially hot-pressed mycelial materials. Numerous other application possibilities exist for hot-pressed mycelial materials, which we would very much like to continue researching.”

In the future, the lightweight and stable bio-composite material could be used in the construction industry, for example. Here, the innovative process could be used to produce insulation boards or panels similar to MDF for interior construction. The numerous positive properties of the material – it is heat-insulating, isolating, moisture-regulating and, furthermore, fire-resistant – could be utilized in this way. “The areas of application for mycelium-based materials are manifold. We are therefore delighted to have been given the opportunity to provide the audience at the Braunschweig theater with an insight into the application possibilities of this pioneering bio-composite material,” said Mr. Christ.