Symptoms
- Bow hair looks slack even when tightened
- Hair touches the stick when tension is applied
- Individual hairs are breaking or falling out
- Bow doesn't grip the strings well when played
Likely causes
- CommonBow tension screw not tightened enoughThe simplest cause; the screw at the frog end needs turning to increase hair tension before playing.
- CommonNatural hair stretch over time or with humidityBow hair stretches with humidity and age, needing more turns of the screw to reach proper tension.
- CommonWorn-out or old bow hairHair loses its grip on the strings after months of use and needs replacing (rehairing), not just tightening.
- PossibleBroken or slipping frog mechanismIf the screw spins freely without tightening, the internal eyelet or screw mechanism may be worn or stripped.
- Less commonHair coming loose from the frog or tip plugThe glue or wedge holding hair in place at either end can fail, especially on an older bow.
What to do
- Turn the tension screw at the frog (the part near your hand) clockwise gradually while checking hair tension.
- Tighten only until there's a pencil-width gap between the hair and the stick at the middle; never over-tighten.
- Always loosen the bow hair fully after each playing session to prevent the stick from warping.
- Check for visible breaks, thinning, or shedding hair across the width of the ribbon.
- If the screw turns without any tension building, stop tightening and have the mechanism inspected rather than forcing it.
- Avoid touching the bow hair with your fingers, since skin oils reduce its grip on the strings.
- If more than a few hairs are broken or the hair looks dark and slick, plan for a rehair soon.
Tools and parts
- None (adjustment uses the bow's own screw)
Bow rehair serviceSearch: “violin bow rehair”
When to call a pro
If the tension screw won't hold, or the hair is worn and no longer grips the strings well, take the bow to a string instrument shop for a rehair or frog repair.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.