The red sticker shows the path of the bow screw while crossing strings in the Bach Partita.
Aim for an oval shape to minimize string-cross action, as this will help you keep good contact between bowhair and string in order to produce a clear resonant tone.
The degree of oval or circle in the pattern depends on the length of bow stroke and height of string cross.
Aim for the same bowhair inclination on each string....
