Bow change
Change of bow direction at note boundaries.
What it means
A bow change is the moment at which the direction of the bow's movement reverses — from down-bow to up-bow or the other way round. It is technically the most delicate point of bowing, because at that instant the string briefly loses its excitation. When the change succeeds, you do not hear it; when it fails, a gap, a click, or a sudden jump in volume results.
In the notation
The bow change is seldom written out explicitly but follows from slurs and bowing marks: where a slur ends, the direction changes. In edited parts, editors sometimes mark a change within a long note so that a whole section changes at the same spot and the sound stays seamless.
Musical use
The art of making many bow changes inaudible is a prerequisite for singing lines; an Adagio stands or falls with it. Conversely, the change can be deliberately audible and serve as articulation, for example in dance-like or march-like music in which every note is meant to start afresh. With long notes that outlast the bow, a section deliberately distributes the changes unevenly, so that not everyone reverses at once and the sound keeps going.
Performance practice
Prepare the change instead of waiting for it: shortly before the turning point take a little speed out, and let hand and fingers cushion the change of direction while the arm is already moving in the new direction. Practise slow whole notes with the metronome and listen specifically to the seam alone. At the frog the change tends to bump, at the tip to disappear — practise both ends separately. In quiet passages, a somewhat slower bow speed with constant arm weight helps. In the orchestra, agree staggered changes with your stand partner so that the line continues.
Remember that the change at the frog and at the tip poses different problems: at the frog there is a risk of bumping from the weight of the bow, at the tip of the tone disappearing. Practise both ends separately and at different volumes. With sustained chords in a section, it helps to stagger the changes deliberately and to enter the spots in the part. Make sure the contact point is kept during the change, because slipping toward the fingerboard makes the tone thin.