Qualities essential for ideal violin tone wood include low density, high speed of sound and a high modulus of elasticity, Swiss researcher Francis W. M. R. Schwarze says, and in the late 17th and early 18th century the famous violin maker Antonio Stradivari found those qualities in wood that had grown in an unusually cold period between 1645 and 1715.
Long winters and cool summers made the wood grow very slowly and evenly, creating low density and a high modulus of elasticity, Schwarze said.
Modern violin makers have no source for such a wood, but Schwarze say his fungus treatment can create it.
Two species of fungi can decay Norway spruce and sycamore -- the two important kinds of wood used for violin making -- in a way that improves their tonal quality.
"Normally fungi reduce the density of the wood, but at the same time they unfortunately reduce the speed with which the sound waves travel through the wood," Schwarze said.
"The unique feature of these fungi is that they gradually degrade the cell walls, thus inducing a thinning of the walls. But even in the late stages of the wood decomposition, a stiff scaffold structure remains via which the sound waves can still travel directly."
Before the wood is used for a violin, it is treated with ethylene oxide gas to ensure fungal growth is completely stopped.
"No fungus can survive that," Professor Schwarze said.
In a blind test against a Stradivarius, a jury of experts listening to two violins played behind a curtain reportedly thought the violin made from wood Schwarze had treated with fungi for nine months was the actual Stradivarius.
The research was reported in a release from the Helmholtz Association of German Research Centers.