Not all viola bows are created equal. The bows are constructed of materials ranging from exotic woods to carbon fiber, graphite composites or fiberglass. Some are geared toward professional players, and others serve the needs of the mid-level and beginning musician. Most viola bows weigh approximately 2.5 ounces (70.87 g) and contain 175 tightly strung horse hairs. It usually is best for one to perform a bit of research and comparison shopping when considering a viola bow, because prices vary greatly between retail providers and manufacturers.
Two primary factors determine the difference in viola bows. The first is the bow's sturdiness. The viola is a mid-sized instrument, and playing it requires a greater string pressure than lighter, smaller instruments like the violin. Luthiers and viola teachers often recommend that beginners start with a fiberglass bow; these are relatively inexpensive and can stand up to the mistakes and inadvertent abuse of the novice player.
Advanced and professional players typically opt for viola bows made from pernambuco wood. Pernambuco is highly regarded for its tonal qualities and response, but this Brazilian wood has grown increasingly scarce because of years of over-harvesting. These bows typically are very expensive but are noted for an extremely long lifespan. Pernambuco viola bows are reputed to provide the type of spring and smooth action that can be appreciated only by an advanced player.
The second consideration that separates viola bows is length. The physical size of the musician is taken into account when selecting a bow, meaning that variations in length are almost endless. Measurements typically are taken between the neck, palm and wrist to provide a bow that allows for the most accurate playing. This is particularly important as it pertains to beginners or novice players, because a poorly fitted bow might cause the young musician frustration and cause him or her to avoid practice.
Viola bows are available in either octagonal or round styles. The shape of the bow makes little difference in string reaction, and the choice of either version is wholly dependent on the musician's aesthetic preference. Violas do not have a standard size, and the instruments generally are purchased based on the age of the player. A child might play a viola that is 12 inches (30.48 cm) in length, whereas an adult would be more likely to perform on an 18-inch (45.72-cm) model. In either case, viola bows are designed to match the size of the instrument.