Rehairing Guidance!

When does my bow need rehairing? A checklist:

  • many broken hairs from the playing edge (playing on it in this condition will cause
  • increased need for rosin to get the necessary grip (you’ll see it on the instrument as well)
  • hair length wrong for the season:
too short—very dangerous to the head and camber;
too long—very dangerous to the end of the stick and the button
  • I recommend rehairing every six months (professionals as often as necessary)—that correspond with one dramatic weather changes (in Maine these changes occur near Thanksgiving—temperature and humidity drop and home heating systems come on and Easter—temperature and humidity go up and the furnace goes off)
  • Something contaminates the hair (oils from the hand, polish; a bow came in recently smelling suspiciously of peanut butter, although the owner insisted it was just a lousy hairing!)
  • Bugs in your bow case can eat bow hair: the bow will need to be rehaired and the case will need immediate attention. Vacuum out the case and store cedar blocks or a few drops of lavendar essential oil. As a rehairer, I do not allow the old black “coffin” cases into my shop. The felt lining seems to attract these small, hard shelled bugs that will very quickly destroy the bow hair. Evidence can be found in the case if you suspect bug damage (shells) and the hair will be cut straight across, with obviously chewed ends.

What is a good rehair?

  • fresh and responsive, unbleached horsehair
  • hair spread to the full width of the ferrule
  • even-tensioned hair (not looser on one side or the other)
  • hair length appropriate to the season:
Winter: longer hair to allow for shrinkage
Summer: shorter hair to allow for stretching
  • hair length that allows for the hair to be loosened to remove tension from the stick when not in use, to avoid warpage
  • A good rehair is not overloaded with hair—putting more hair than just an even band at the ferrule endangers the fragile head and frog mortices, and has a dramatically negative effect on sound production. There is ample evidence from scientific study and personal experience that proves more hair = less sound—as the sound is quieted by the layers of hair. The sound is without clarity and elasticity is needed for quick response, the frustrated musician applies more rosin, exacerbating the problem.

Advice for the Bow Rehairer

When a musician asks that I “load it up,” I assume that they want a big, clear tone with hair that will last for as long as possible. This I will achieve for them not by overloading, but by installing a modest amount of the finest quality hair and a quick lesson on rosin choice, rosin application techniques, and a reminder to regularly remove excess rosin from the strings. Even when a musician asks that I “load it up on the playing side” I rehair the bow normally.

Go back to my Restoration : Repair : Rehair page.