The crafting of string instrument and violin bows is an art form that has been refined over the centuries. We can gain valuable insight and understanding through the lens of science to help along our understanding.
Making Music
Much of the characteristic beauty of the violin sound comes from bowing the strings. While a plucked string vibrates about its fundamental frequency with limited overtones, a bowed string resonates repeatedly with the slip-grip-slip action of the bow as it glides across the string. This sawtooth excitation of the string produces many of the complex higher-order harmonics that typify the distinctive voices of the violin family.
The quality of the bow is an integral component in producing the characteristic resonance of the violin. And the skilled player adds considerable nuance and complexity through bowing techniques such as legato, spiccato, martelé and ricochet. Modern players also incorporate the percussive chop for a groove-based percussive effect.
The subtleties of grip, slip, attack and force production are complex, and require the bow to be responsive to numerous variations used by the violinist to impart movement to the string.
Bow Making
Until fairly recently bows have typically been constructed from wood. Light, strong, slow-growing hardwoods are preferred for strength and stiffness.
The best known and most sought-after timber for bows is Pernambuco wood. Other South American species used for bows are known somewhat generically as brazilwood. The timber must be seasoned over many years before it’s ready to be crafted into a bow.
Due to excessive harvesting over centuries, a number of species are listed as endangered and are increasingly rare and difficult to source.
Fortunately, there are a number of viable alternatives to the traditional timber bow. Suitable light yet strong materials, such as fibreglass and carbon fibre, have been developed. There are hybrid solutions that mix wood with modern materials in composite bows.
Carbon fibres, resin percentage, hollow and hollow-filled bows are all in the mix. Using carbon, glass and kevlar materials as a substrate for applied resins yield similar strength and acoustic properties to that of wood.
Attempts to match the lightness and rigidity of wooden bows have yielded stunning results. Modern alternatives compare favourably to all but the very best and most expensive Pernambuco bows.