Interzum 2019

•••9••• Innovationen Rotten to the core – magic of nature Swiss researchers develop a process to decorate wood using fungi for design furniture production Sometimes there is true beauty to be discovered in very unusual places. Like Phoenix from the ashes, the coveted truffle beech is made from rotting wood on the forest floor. Uniquely patterned, it has been a sought-after as a raw material for furniture produc- tion since antiquity. However, the search for natural truffle beeches is tricky. Even those who delib- erately leave tree trunks to rot in the forest have to wait years before they can hope to obtain wood that is decorated with fun- gal-induced patterns and, further- more, still usable. Empa research- ers have developed a technology, with which hardwoods such as beech, ash and maple can be spe- cifically treated with fungal cul- tures so that the patterns in the wood can be controlled. Fungi fight battles for resources in thewood The fine black lines running through the wood are the traces of a battle. Sometimes they me- ander turbulently towards each other and separate small plots with lightened background. In other places, the dark drawings flow calmly as if they wanted to remind us of a boundary that none of the participants likes to cross: Fungi that have fought in a battle for territory and resourc- es in the wood clearly separate themselves from each other with pigmented lines. With these de- marcation lines, the fine threads of the fungal community not only protect their colony from other fungi – the black boundary also ensures that bacteria and insects stay away and the habitat retains an ideal amount of moisture. “We were able to identify fungi growing in nature and analyze them in the laboratory to select those with the most favourable properties as wood finishers,” says Hugh Morris, a scientist in Empa’s Applied Wood Materials lab in St. Gallen. For example, the brittle cinder fungus and the Tur- key-tail when matched with each other leave black lines caused by the pigment melanin and at the same time bleach the surround- ing wood thanks to the fungal enzyme laccase. “This creates a pattern with a particularly strong contrast in the wood,” explains Hugh Morris. Controlled process Depending on the combination of fungal species, the lines are wild and impetuous or almost geomet- ric. The researcher is convinced that the fungi can even, in time, be trained to write words in the wood. The gentle bite of the fungi that are used in the Empa labo- ratory is particularly favourable: Despite their pronounced talent for drawing, the selected candi- dates hardly gnaw their substra- ta. “Although fungi generously supply the wood with pigments, the wood retains its stability and shape,” says Hugh Morris. However, the fact that the artis- tic process can be controlled and geared towards the desired result is not only owing to the type of fungus, the researchers also de- veloped a process, with which the wood is ready for processing within weeks. One of the reasons for this rather fast processing is that the selected fungal species are able to grow in the wood with considerably lower moisture lev- els. This means that the raw ma- terial does not have to be dried long, costly or energy-intensive before being processed into fur- niture. Productionmethod to be developed Together with an industry part- ner, the researchers are now in the process of implementing an efficient and ecologically sustain- able production method. This also includes the use of regional wood. “Beech wood is a hardwood that is common in Switzerland but ap- pears uninteresting to furniture designers,” explains Managing Director Jakob Koster. With mar- ble wood from local beech trees, however, it is possible to offer sought-after products on the Swiss timber market with an an- nual volume of around three bil- lion Swiss francs. Further uses In addition to furniture, parquet floors and kitchen fronts, mar- ble wood can also be used for decorative objects and musical instruments. Unique pieces have always been created from pat- terned wood. With the new tech- nology, spalted wood can now be produced faster, more sustainably and with the desired marbling. Fungi naturally populate wood and generate pigmen- ted lines which serve as a demarcation line to separate themselves from other fungi. Photo: Empa Spalted wood from the lab: depending on the kind of fungi used, the course of the pattern in the wood can be controlled. Photo: Empa Continued from page 1