Détaché
Détaché is French for "detached," and it's the stroke you play when the music tells you nothing else: one separate bow per note, alternating down and up, smooth, using the full written length of each note. It is the ground every other bow stroke is a modification of, so it's worth more slow attention than it looks like it deserves.
On the page
There's no symbol for détaché. Its notation is the absence of a slur, a dot, a dash or an accent — plain noteheads, nothing above or below them. When you see that, you play separate bows.
What to listen for
Every note should sound the same — same attack, same volume, same tone — whether the bow is travelling down or up. The join between two notes should have no bump and no gap: the sound is unbroken, only the bow's direction changes. Close your eyes and you shouldn't be able to hear where each stroke begins.
Where in the bow
Détaché doesn't have a fixed home — it follows the speed of the notes. Fast notes get
short strokes near the middle of the bow, moved from the forearm. Slower, broader notes use
more of the bow, up to whole bows (that's grand détaché — the-detache-family). Practise
the same passage at the frog, then the middle, then the tip, then whole bows: each teaches a
different part of the control.
On a real tune
How to play it
Pickup notes near the middle of the bow, small even strokes — match the up-bows to the down-bows. Then one slow whole bow on the long A, dead steady (that's the son filé from Movement A).
The usual mistake
Two things go wrong, and they're linked. First, the up-bow comes out weaker than the down-bow — gravity helps the down-bow and you have to consciously match the up-bow to it. Second, players slow the bow down at the change of direction, which makes a little dip in the sound at every join. Keep the bow speed constant straight through the turn, and keep the same weight into the string from the arm. The direction change should be invisible in the sound.
Try
On the open D string, play four slow détaché strokes — down, up, down, up — listening only for whether the up-bows match the down-bows. When they do, move to the D-string scale above. Stop the moment your bow hand or shoulder tightens; a tense détaché only teaches tension.
Read this stroke now — recognise plain noteheads as "separate bows." Playing an even détaché takes months of long tones and slow scales, and that's normal.