Bariolage
A rapid string crossing at the same pitch.
What it means
Bariolage is the name for a string technique in which one crosses back and forth between two strings while the pitch stays the same or varies only slightly. Usually an open string stands opposite a stopped note of the same pitch on the neighbouring string. Because the open and the stopped string sound different — the open one brighter and richer in overtones, the stopped one warmer and coloured with vibrato — a shimmering change of tone colour arises with a practically unchanging melody.
In the notation
Bariolage is recognisable by rapidly repeated or oscillating notes, often in sixteenths, together with a fingering or string indication. A small circle over the note expressly calls for the open string, a roman numeral or an indication such as sul G prescribes the string to be used. Without such hints it remains a matter of interpretation whether a passage is meant as bariolage.
Musical use
The technique has belonged to the repertoire of violin music since the Baroque and is gladly used for places with unchanging harmony and much motion, for instance in preludes with running sixteenths. The effect there is not virtuosic display but tone colour: the ear hears an almost stationary line that nonetheless shimmers constantly. In the music of the nineteenth and twentieth centuries too bariolage appears, sometimes heightened to continuous string oscillation over whole sections. From the tremolo it differs in that not the bow speed carries the effect but the change of strings.
Performance practice
Keep the bow as calm as possible and work only with small arm movements; the string changes arise in the elbow, not in the wrist alone. Find the height at which both strings are reachable with minimal movement, and practise at first slowly as a double stop, to find this level. See that the stopped notes do not become distinctly louder than the open ones — otherwise the passage seems bumpy rather than floating. A slight vibrato on the stopped note strengthens the difference in colour; too much of it makes it clumsy. If the passage becomes fast, think in groups rather than in single notes.