Arco
“With the bow”, cancelling pizzicato.
What it means
Arco is the Italian word for bow and, as a playing instruction, the call to bow again. The marking almost never stands at the beginning of a piece, for bowing is the normal case. It appears where a preceding instruction must be cancelled — as a rule pizzicato, occasionally also col legno, in which one strikes with the bow stick.
In the notation
Arco stands in italics above or below the staff, exactly at the note from which bowing resumes. Good engraving leaves a little air before this note, because the player must first take the bow back into the hand or set it on the string. In orchestral parts the marking is often additionally boxed or printed enlarged, so that it is not overlooked in quick reading.
Musical use
The change back to the bowed note is a change of tone colour and is composed as such. After a plucked passage the first bowed note seems softer, longer and more connected; the contrast often carries a formal boundary, for instance the transition from an accompanying section back to the melody. In music since the late nineteenth century pizzicato and arco also alternate within a few bars, so that the string group switches back and forth between two sound worlds.
Performance practice
The critical point is not the bowing itself but the time before it. Plan where the bow stays during the pizzicato: with short interruptions in the hand, the fingers between the stick and the palm; with longer sections, set down. If you pluck with the index finger of the right hand while holding the bow, align yourself in good time to the first bowed note, so that it does not scratch. Set the bow, if possible, quietly on the string already during the rest and begin with calm arm weight. In the orchestra it is worth agreeing the moment of taking up the bow again with the desk partner, so that the group re-enters together and noiselessly.