Koster AG Holzwelten and Empa create spalted wood

(CONNECT) Koster AG Holzwelten, a family-run carpentry business based in Gossau in the Swiss canton of St.Gallen, has worked with Empa to develop spalted wood, a type of marbled wood that is characterized by patterns of fine black lines caused by a fungus. This unique wood, which used to be a rare chance find, can now be produced in an annex of the carpentry workshop using stainless steel containers, laboratories, and climate and vacuum chambers. According to a statement, the product is being marketed under the name Myrai.

As part of a joint Innosuisse project, the carpentry workshop and Empa developed a standardized, scalable process for producing spalted wood. First, boards made from local hardwoods such as maple, beech, and ash are brought to the correct humidity in a vacuum chamber, sterilized, and inoculated with the fungus. They then spend several weeks in a climate chamber to allow the fungus to grow and create its patterns. Finally, the wood undergoes a technical drying process, which simultaneously kills the fungus.

“The special thing about this particular fungus is that it does not break down the heavily lignified areas of the cell wall; the wood thus retains a high degree of flexural strength,” Empa researcher Francis Schwarze is quoted as saying. The fungus expert works in Empa’s Cellulose & Wood Materials department in St.Gallen.

The resulting spalted wood is particularly suitable for decorative applications such as furniture, interior design, and musical instruments, according to the statement. Through the project, Koster AG Holzwelten gained expertise in controlling and refining the appearance of wood. Jakob Koster, former CEO of the company, now plans to focus on sales and further innovation of spalted wood. According to Koster, demand is already high. The partners say they also have new ideas for further collaboration. ce/nta