I recently put together a video where I start a freshly rehaired violin bow with rosin:
Starting a Violin, Viola, or Cello Bow with Rosin
- Tighten the bow to playing tension or slightly tighter.
- If you are using new rosin, lightly scuff with coarse sandpaper. This creates a thin layer of fine dust to start the hair and rosin.
- Placing a cleaning cloth under the head, lay the stick down with the hair facing you.
- Use your thumb to protect the ferrule and cake of rosin. Apply rosin in short strokes, rotating the cake of rosin as you go.
- The rosin may gloss back up and become polished on new hair. Some additional scuffing throughout the process may be needed.
- You can see, hear, and feel where the rosin is grabbing and where more needs to be applied. Continue to work the rosin into the hair where it needs it.
- A clean toothbrush can be used to work the rosin in towards the head and back towards the ferrule. It can also be used to lightly comb the rosin into the hair and even it out.
- End with just a handful of long strokes over the entire length of the hair to even out the coverage.
- Wipe down the stick with a polish cloth to remove any rosin dust that may have accumulated from the rosining process.