acoustics, Cornell University, electron microscope, gut string, harmonic series, Jun-ichi Matsuda, Katherine Selby, Nara Medical University, Nephila maculata, nylon string, Shigeyoshi Osaki, spider, spider silk, steel string, Stephen Battersby, Stradivarius, string tone, Tchaikovsky, timbre, violin
Shigeyoshi Osaki at Nara Medical University in Japan has studied the properties of spider silk for thirty-five years. In the past decade he has focused on trying to turn the silk into violin strings, even taking lessons on what was required of a string in terms of strength and elasticity.
Osaki learned how to coax Nephila maculata spiders to spin out long strands of dragline, the strongest form of silk. He bundled filaments together and twisted them, then twisted three of these bundles together to make each string. The thickest of these, the G string, holds 15,000 filaments.
The strings turned out to be tightly packed and strong. The key seems to be that the individual filaments changed shape when twisted: an electron microscope revealed that their circular cross sections turned into polygons, which nestle together more tightly than cylindrical strings.
This came as a surprise. “To my knowledge, no one has observed such a change of cross section. I doubted my experimental results,” says Osaki. The spider silk must be deformed by the twisting process.
“The material is a bit squishy, like twisting plasticine,” says physicist and violinist Katherine Selby at Cornell University in Ithaca, New York.
Osaki tested the new strings by comparing their performance with three established materials: steel, nylon and gut. He says that the spider silk has a unique and “brilliant” timbre, or quality of tone. You can judge for yourself in this snippet of Tchaikovsky, played by Jun-ichi Matsuda on a Stradivarius violin using all four types of string.
The timbre seems to result from a difference in how harmonics – frequency multiples of the main note – reverberate in the spider silk strings compared with other materials. Spider string has strong high harmonics, while steel and nylon tend to be stronger in low harmonics. Osaki does not yet know what mechanical properties lead to this acoustic performance.
Selby is impressed. “What people crave about natural gut strings is a certain complexity,” she says. “Spider strings also have this brilliant sound – even more than gut.”
“It is impressive when you remember these are prototype strings, just out of a material science lab, being compared with commercial strings perfected for years,” she adds.
Selby points out that the high strength of spider silk may give it another advantage: “You could have a thinner string for playing the same pitch, which would be a bit more bendy and responsive – it would hit a note quicker.” The material could be especially suitable for thin E strings, which are very fragile when made from gut.
“Is it something all violinists will like? That’s an open question. It will have some surface texture, like a rope. Some people may find that off-putting as they slide a hand up and down the neck. I think these will be gourmet strings,” Selby adds.
The price will be too steep for most fiddlers in any case, but Osaki is now trying to find a way to produce the strings in larger numbers.
Stephen Battersby – New Scientist