Microorganisms (fungi, algae, lichens and bacteria) can colonize biofilms, shorten their life span, impair their function and aesthetic appearance and cause hygienic problems. Most fungi are considered to be a public safety hazardalthough the beneficial effects of fungi far outweigh their negative. If they are applied selectively they can optimize material properties. For pure and appliedresearch we use a range of fungal species and enzymes to positively enhance the properties of wood. The application of wood inhabiting fungi results ina significant improvement of the acoustic properties of tonewood. Wood durability of refractory, native tree species such as Norway spruce and Fir is enhancedby the bioincising process which results in a significant increase in wood permeability. Bioincising is a promising technology to enable an efficient distributionof wood modification substances and to promote the efficiency of the desired property improvement.

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Tonewood

• Superior tonewood has a low density and high Young‘s modulus of elasticity. The acoustic properties of Norway spruce and Sycamore wood can be improved with a controlled degradation process.

Bioincising

• Wood of Norway spruce and white Fir is weakly durable, has a low liquid permeability and can be only poorly treated with selected wood modification substances.

Fungal Biotechnology

• Wood decay fungi secrete enzymes which specifically attack the wood polymers. Lignin-degrading enzymes such as laccases can be used for green chemistry, or the production of wood compound materials.

• Determination of the cause for microbial decomposition of wood plastics, metals, organic and an organic materials
• Research on the selective modification of wood with fungal species and fungal-derived enzymes
• Elucidation of the durability of wood against microorganisms under different environmental conditions
• Determination of the efficiency of wood preservatives and wood modification methods against microbial colonization and decomposition.
  

Contact: Francis Schwarze

Mycowood: improved acoustic properties for violins
The quality of wood for the manufacture of music instruments (tone wood) is determined by its physical properties. Wood with a low density, high velocity of sound and modulus of elasticity has superior properties i.e. its resonance characteristics and sound radiation is improved. The objective of our investigations is to improve the material quality of tone wood by exposing it to decay fungi under controlled conditions. The latter fungi differ from most other fungi, as they reduce density but do not degrade highly lignified cell wall regions resulting only in negligible changes in the velocity of sound. We are in the process of developing and optimizing the treatment methods for the modification of Norway spruce and maple wood and defining factors that are essential for the material quality: mass loss, velocity of sound, modulus of elasticity, eigenfrequencies and other physical properties. On the basis of a patented procedure, it is our long term objective to manufacture a prototype violin assembled with decayed wood.
Contact: Francis Schwarze

Enhanced permeability of spruce by fungi modification
Aspiration of bordered pits in Norway spruce wood is the main reason why the treatibility with preservatives is greatly inhibited for increasing the durability against micro-organisms. If this restriction could be overcome wood could be treated more effectively. For this purpose Norway spruce wood is exposed to the white-rot fungus Physisporinus vitreus that selectively degrades the pit membranes, without altering the mechanical properties of wood.  At present we are undertaking studies to optimize conditions under which the colonization of wood by the fungus is improved with the objective to upscale our patented procedure as a biotechnological method for industrial purposes.
Contact: Francis Schwarze

Project 'Resistance of thermo-hydro-mechanically (THM) densified wood to colonisation and degradation by wood decay fungi
Recently a process was developed for densifying wood by thermo-hygro-mechanical (THM) means. THM densified wood is less hygroscopic, more dimensionally stable and its density is several times that of the raw material. Tests on THM densified wood have shown significant improvement in mechanical properties, reduction in hygroscopicity and little shape memory. The objective of our research, is to determine the reasons for the resistance of such wood to colonization and degradation by decay fungi. For this purpose we are examining wood degradation patterns within the modified wood substrate, the micro-morphological structure of THM-densified wood and the parameters that are responsible for the elimination of its shape memory.
Contact: Francis Schwarze

Development of a durable, low fungicide content coating system for wood facades
In recent years, wooden facades treated with water-borne coatings show an increasing tendency to discoloration or damage by mould and blue-stain fungi after a short period of time. Within the scope of a KTI research project in collaboration with the UAS for architecture, building structure and wood (HSB Biel), and industrial partners of the woodworking, biocide and coating industries, a range of water-borne coating systems are being assessed. It is envisaged that the appraisal of a range of biological, physical and chemical factors may allow a better understanding why some coating systems are colonized earlier than others. At the Empa we examine whether the coating system itself can be utilized by fungi as a nutrient source or if the resistance of the active substance is influenced by abiotic conditions such as heat, frost, leaching and ultraviolet light. Furthermore spore adhesion to the surface of coatings and subsequent spore germination will be investigated. A new approach is based on the biotechnological preconditioning of the wood surface by appropriate microorganisms prior to application of the primer to achieve a better absorption and penetration depth of preservatives.
Contact: Francis Schwarze