Refined wood is not only used for designer furniture and tableware. Musical instruments, such as electric guitars, can also be crafted with spalted wood.
Refined wood is not only used for designer furniture and tableware. Musical instruments, such as electric guitars, can also be crafted with spalted wood.
Fungi that decompose tree trunks can conjure up real works of art in wood. In nature, however, the decay-causing fungi not only decorate the tree, but also destroy it. Researchers from the Swiss Federal Laboratories for Materials Science and Technology (Empa) are now teaching the fungi how to draw. The result: upscale marbled wood that can be processed into design furniture or musical instruments.
 
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 production since antiquity. However, the search for natural truffle beeches is tricky. Even those who deliberately leave tree trunks to rot in the forest have to wait years before they can hope to obtain wood that is decorated with fungal-induced patterns and, furthermore, still usable. Empa researchers have now developed a technology, with which hardwoods such as beech, ash and maple can be specifically treated with fungal cultures so that the patterns in the wood can be controlled.
 
Magic of nature: fungi that populate dead wood generate a captivating pattern of colors and lines with pigments. Credit: Jan Thornhill
The fine black lines running through the wood are the traces of a battle. Sometimes they meander 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 resources in the wood clearly separate themselves from each other with pigmented lines. With these demarcation 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.
 
Marbled wood from the lab: Depending on the kind of fungi used, the course of the pattern in the wood can be controlled. Credit: Empa
"We were able to identify fungi growing in nature and analyze them in the laboratory to select those with the most favorable 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 Turkey-tail when matched with each other leave black lines caused by the pigment melanin and at the same time bleach the surrounding wood thanks to the fungal enzyme laccase. "This creates a pattern with a particularly strong contrast in the wood" explains Hugh Morris.
 
Depending on the combination of fungal species, the lines are wild and impetuous or almost geometric. 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 laboratory is particularly favourable: Despite their pronounced talent for drawing, the selected candidates hardly gnaw their substrata. "Although fungi generously supply the wood with pigments, the wood retains its stability and shape," says Hugh Morris.
 

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Author Andrea Six works for The Swiss Federal Laboratories for Materials Science and Technology, an interdisciplinary Swiss research institute for applied materials sciences and technology. 
 

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