col legno tratto
A string technique in which the bow is drawn across the strings using the wood of the bow rather than the hair
In Depth
While [col legno battuto](/term/col%20legno%20battuto) (bouncing the wood on the strings) is more common, col legno tratto asks the player to draw the wooden stick along the string, producing a ghostly, scratching whisper. The sound is barely audible and profoundly unsettling, used for atmospheric and supernatural effects. Penderecki and other avant-garde composers employed it extensively. String players are often reluctant to perform the technique, as it can damage expensive bows.
Professional orchestral players sometimes keep a cheaper spare bow for col legno passages to avoid damaging their primary bow.