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Common Bow Hair Problems
A blue heart made of dyed hanks of horse hair.

Bow hair care is a frequent topic of conversation with our customers. Whether they come in because they can't get a good grip when bowing, or the hair on their bow has suddenly become too tight, or because the bow has become difficult to tighten, we find many customers have questions about the hair on their bow. 

Today we will touch on a few of the more common problems we see and explain what these problems may mean.

Symptoms of a Bow in Need of a Rehair

The Bow Won't Tighten Anymore
This is typically one of the main symptoms of a bow in need of a rehair.

Still confused? Here is a basic explanation of how the hair on your bow is tightened every time you use it.

When the bow screw is turned on a violin, viola, cello, or bass bow, the frog is pulled along the interior bow stick mortise (see bow parts listed below).
A diagram of a violin bow stick. Labeled are the bow screw, mortise, bolster, wrap or lapping, eyelet and ferrule.

As the frog slides along the mortise, the bow hair is pulled tighter and tighter against the tension of the bow stick.

When the frog has run out of mortise to slide along, the bow screw can no longer be turned. Bow hair that has stretched with use has not only reached the end of its length, it has also lost the ability to offer a clean sound.

It is important to rehair a bow when it becomes difficult to tighten to improve the sound quality, the play-ability of the bow, and to avoid prematurely wearing out the frog eyelet and bow screw threads. 

The Bow is Making a Scratchy Sound

This is typically a symptom of one of two things:

1. The player has applied too much rosin.

To determine if there is excessive rosin on a bow, we do a visual inspection of the bow hair. A bow with excessive rosin will have very, very, very white hair and can tend to create a rosin cloud when the player uses the bow. If the bow hair is still on the shorter side and has been replaced fairly recently, we may recommend playing through some of the built-up rosin to try and preserve the existing bow hair.

However, if the rosin build-up is too excessive, we may have to recommend a rehair to offer a fresh start. 

2. The bow needs a rehair.

There comes a time when a player has simply played through the life of the bow hair. With repeated use, the bow hair requires the player to apply more and more rosin to try to replicate the same grip they once had when the hair was new and fresh. This build-up of rosin creates a scratchy sound and the old hair requires more work to use. 

With normal use, most bows require a rehair every 6-12 months.  

The Bow Hair is Visibly Dirty

This feels like a fairly obvious problem and is often caused by touching the bow hair. Many players rest the hair of their bow against their thumb or finger(s) when carrying their bow or holding it in rest position. The oils and dirt on your hands are the most common cause of this build-up. Avoid touching your bow hair when possible and rehair your bow regularly. (See photo below.)
A viola bow rests in a wooden repair jig. The naturally white hair is blackened with dirt and about 20 percent of the hair is missing.The bow pictured above is an example of a bow with missing and dirty horsehair.  

The Bow Hair is No Longer a Flat Ribbon

The most common cause of this problem is missing bow hair. (See photo above.)

With regular use, it is common to break off a hair or two on the bow. Over time, minor hair loss adds up, and the hair that once laid as a flat ribbon across the ferrule is now a thin, clump of hair. Once enough hair goes missing, the wood spread wedge that holds the hair in a flat ribbon can fall out. 

Bow Hairs are Breaking or Exploding

A magnified view of the horsehair on a bow. A single hair sticks out which has small, uneven bite marks along its surface.You may be the victim of bow bugs! Although these critters can cause a nuisance, this problem is easily treated and is something we have discussed in a previous "Notes from the Bench." Click here to learn more about bow bugs.


The Bow Hair is Suddenly Too Tight

This is the number one bow conversation we have with customers in the dry winter months. The conversation usually goes something like this:
"Last night I went to practice my instrument and I opened my case to find my bow so tight that I couldn't loosen it any more. I was afraid to use it! The crazy thing is-- it wasn't like this when I practiced 3 days ago!"
In this circumstance, we typically take into consideration the current outside temperatures and ask the following follow-up question: 
"What type of humidifier are you currently using in your case?"
We ask this question because a drop in humidity, similar to one we would see when the heat in our homes is pumping, is enough to cause the hair on a bow to shrink.

In fact, when we rehair bows during dry fall and winter months, we leave the bow hair a little on the longer side to compensate for a potential drop in humidity once a bow leaves our store.

Believe it or not, in a drastic humidity change, bow hair can shrink enough to cause a dramatic change in the length on the bow stick--even to the point of causing wood bow heads to snap off of bows!
(The bow pictured below was left tightened in low humidity and the head of the bow snapped off.)
A violin bow stick whose head has broken off and is missing. A head of a violin bow which has been broken off of its stick.
How to Avoid This Problem
Humidify, humidify, humidify!
We often feel like a broken record when talking with customers about humidity, but maintaining an in-case humidity level of at least 40% humidity can make all the difference when it comes to preserving valuable investments. The easiest way to maintain this level of humidity is an in-case humidifer.

In addition to bow hair shrinkage, instrument seams, loose fingerboards, body cracks, slipping pegs, and wolf tones are just a few things that can become a problem when the humidity drops each season. 

In Case of Emergency

In cases of dramatic bow hair shrinkage, you can set the bow in a steamy room to see if the hair will naturally stretch out a little until you can get a case humidifier in place to stabilize your bow.  If the bow is so tight that your stick is now straight or beginning to arc in the opposite direction, remove the screw from your bow and--taking care to not twist or turn the hair-- remove the frog off of your bow and bring the bow into the shop for evaluation. 

In the market for a case humidifier? Check out our web store to learn more about The Precipitube Humidifier®.

To learn more about the importance of humidity regulation in instrument and bow care, click here.

When to Come into the Shop

Although we have listed the most common culprits of these bow problems, there can be other issues causing some of these problems. We offer free repair evaluations on bows and are happy to help whenever you run into an issue!