By Erin Shrader
Some people can go for years between rehairs on their bow while others seem to need a new hairdo every six weeks. Horsehair doesn’t just “go bad.” Open up a centuries-old piece of furniture and you’ll often find the horsehair stuffing in excellent condition. Bows can hang in the shop for years without needing a rehair (of course, there’s probably a reason they’ve become part of the “permanent collection”). But hair does break and stretch, and eventually—though we don’t fully understand why—stops engaging the string. Sometimes you can tell if it’s time for a rehair by simply looking, other times it’s a matter of feel. A bad-hair day can also be dangerous for your bow.
So, know when it’s time to rehair. Here are some guidelines.
Too many broken hairs on one side puts uneven tension on the stick and will eventually pull the stick to one side. Straightening the stick requires heating, which always involves some level of risk, even in the most experienced hands. Best to avoid this situation if you can by getting a rehair before it’s a problem.
If the hairs always break in the middle of the bow and look like they’ve been chewed off, there could be too much camber in the bow. This can feel nice and stable, but if the stick is too close to the hair at playing tension, the hairs grind between the stick and the string when you bear down on the bow.
If you’re constantly chewing through hair, something about the player-instrument-bow combination may not be working for you. The bow that worked so well on your old fiddle might not make the new one sing, or maybe it’s time to take your instrument in for a checkup. Consider looking for an instrument or bow that gives the response you’re looking for without forcing the bow.
Technique may also be a culprit. A firmer grip and more pressure on the strings don’t necessarily deliver more sound. The bow actually vibrates, as do the strings and the instrument, and the difference in resonance between a heavy grip and a light one is striking. Also, if you find your hand creeping up the bow just a little, your fingers may be instinctively responding to a place on that particular stick that creates a better response or freer sound. Don’t feel glued to a particular spot on principle if a slight variation gives you better tone and response.
In climates with markedly contrasting seasons, it’s quite common to rehair bows in the spring and fall due to changes in humidity. Hair that’s the right length for the dry season can be too long to even reach playing tension when the rains come. Of greater danger to the bow, though, is hair that’s too short for the dry season, which can easily snap the head right off a bow. How can you tell if humidity is a potential threat? If the skin is dry on the back of your hands, check your bow. If you can’t loosen it enough to take the tension off the stick, get a rehair. (If the dry spell is temporary or help is not readily available, refer to the accompanying sidebar.)
If the hair gets too dirty (or smells suspiciously of peanut butter…) just get it rehaired. Some people wash the hair with anything from shampoo and conditioner to dish soap and are happy with the results. But it’s important (and challenging) to keep water away from the ends of the hair and the wooden wedges that hold them in. Moisture-swollen hair and plugs can cause damage or make the wedges fall out. There are commercially available bow-hair cleaners, but in my experience, they just leave a sticky, glassy mess when rosin, softened by the solvent in the cleaner, rehardens around the hair. The solvent for rosin is alcohol, which is also the solvent for the varnish on your stick. Dissolving varnish on the stick is not the same disaster as on your instrument, but why court mishap?
Sometimes it’s a subjective feeling that sneaks up gradually—a feeling that the hair isn’t engaging the strings the way you remember it, or a feeling that you want to keep adding rosin. Ironically, too much rosin can have the opposite of the desired effect. Before deciding that an otherwise “full head of hair” is ready for replacement, try removing some rosin with a soft, clean, dry cloth. If that doesn’t work, and it’s been a while since your last visit to the violin shop, get a rehair.
Occasionally a new rehair just doesn’t seem right. Sometimes it’s perception, sometimes there’s something wrong. If you’ve been playing on too-long hair for a long time, you’ll have become accustomed to the frog sitting farther back on the stick, which changes the way a bow feels or handles. Try getting used to the rehair for a while. If you know something’s wrong, first try taking it back to the shop that did the job, especially if you’ve been happy with its work in the past—the shop could be trying hair from a different supplier or training a new rehair person. It’s hard to correct problems without feedback from the client. If you just can’t work with the shop, ask your colleagues whose rehairs they like. If there’s no one good in your local area, consider checking out some of the new mail-order rehair services. But one caveat: get a real person on the phone and ask about the training and experience of the people doing the work.
This article originally appeared in the OCtober 2008 issue of Strings magazine.