Bowing & articulation
Sul tasto
Sul tasto is bowing over the fingerboard, well away from the bridge, producing a soft, hollow, flute-like tone with very little edge.
Bowing further from the bridge lets a longer segment of the string move freely, which strengthens the fundamental and weakens the upper partials. The result is quiet and diffuse, and it responds badly to pressure, pressing harder over the fingerboard chokes the string rather than adding volume.
Composers use it for hushed accompaniment textures and for colour changes within a sustained chord. The related term flautando describes essentially the same effect with the emphasis on the flute-like quality. Ordinario cancels it.
Related terms
Every term in this glossary is taught in context somewhere in Arco's curricula, on the staff, on the keyboard, and on your own fingerboard at the same time.