Mold and fungi don't get much love, especially from builders and woodworkers. However, some recent findings might make you think twice about the maligned mycelium. On September 7th, Swiss Federal Laboratories Professor Francis W. M. R. Schwarze summarized his research on the benefits of treating wood with certain species of fungi. It won't help you build a better house, but it could make you the next Stradivarius.
For years researchers have analyzed the 17th century violins made by Cremonese masters Antonio Stradivari and Giuseppe Guarneri Del Gesu. A few have come close, but no modern violin has truly been able to replicate the acoustical quality and character of a Stradivarius. Why do they sound so good? Theories have focused on several areas: the thickness of the top and bottom plates, the subtle curves of the design, the precise angles of the neck, the strings and fingerboard, the finish and varnish techniques, and most of all the properties of the wood.
It is commonly accepted that northern Italy and many other parts of Europe and North America experienced a significant and prolonged cold period from about 1400-1800, the little ice age as it sometimes called. The cold weather was most severe in the late 1600's and into the early 1700's when Stradivarius was making his violins. Among other things, the climate change had a pronounced effect on the growth patterns of trees. In the spring, trees tend to put on more porous growth for the transport of water and sap. In the fall, the wood cells (tracheids) are more tightly-packed and dense. The alternating yearly bands of early and late growth are the familiar rings we see, or the grain of the wood. During the cold period, trees grew very slowly, the rings were narrow, and the density of the early and late growth was more uniform.
Uniform density is suspected to be a key factor in the superior resonance properties of antique wood. The theory was explored in 2008 using Computed Tomography (CT), which is normally employed in a medical setting to scan lung tissue. Five violins by Stradivarius and Guarneri were compared to eight quality modern violins. Professor Schwarze says of the results, "On average the wood density of 17th century violins was similar to contemporary violins. However the 17th century violins had a more homogeneous density distribution."
Sections of sycamore wood showing progressive cell wall thinning by Xylaria longipes
How can modern wood achieve that more balanced and consistent density? Enter the fungi. Schwarze discovered two specific fungi (Physisporinus vitreus and Xylaria longipes) that can selectively break down the thicker cell walls in the wood. He explains, "Preferential degradation of thick late wood cells by our fungi results in a reduction in cell wall thickness in the more dense areas (winter growth) of modern wood, thus achieving greater uniformity on the whole." When desired uniformity is reached, the fungal growth is terminated using ethylene oxide gas. The process does not degrade the structural components between the cells, and the wood remains just as strong and elastic. A treated violin is called a "mycowood" violin, or a "fungolin". Schwarze continues, "Reduction in density and negligible alteration of the speed of sound by our wood decay fungi results in a higher sound radiation of the fungal treated violin."
Violinist Matthew Trusler put it to a blind test. While standing behind a curtain, he played both a fungolin and 1711 Stradivarius for a panel of expert judges. The judges and a majority of the other audience thought the humble fungolin was the actual Stradivarius. Professor Schwarze is currently working on 30 more fungolins, and a set of fungal treatment standards for violin wood. He is hopeful that young musicians around the word will one day be able to play on relatively inexpensive violins that sound like a priceless Strad. Bravo!