Hair of a musical bow, coloured scanning electron micrograph (SEM). Stringed instruments such as violins, cellos, violas and double basses, are played with a bow typically made from horse hair. The hair of the bow is coated with a resin called rosin (also known as colophony) to increase the friction when moving the bow over the strings of the instrument. This resin powder is visible on the hair here. Magnification: x535 when printed at 10 centimetres across.