When should I get my bow rehaired?

There are many signs which indicate it is time to have your bow rehaired. The most obvious one is when it is missing many hairs. Most commonly hairs break from the playing side edge. For the violin and viola it is the left edge as you hold the hair facing you when you hold the bow at the frog. For cello and bass it is the opposite side. Continuing to play on a bow that has many hairs missing from one side can not only cause the bow to respond less effectively but can bring on or aggravate warping of the stick. Occasionally hair suddenly starts to pop out in clumps or all at once.

Another obvious sign is if the hair turns very dark or if it doesn’t bite or cling to the string when playing with a moderate amount of rosin. Some people believe the hair has tiny teeth which, with the help of rosin, grips the strings and pulls a beautiful sound with relative ease. I don’t believe this is true. I have studied hair under a microscope and it is my belief that each hair, when first put on the bow, has a different and irregular shape from the other hairs used. Over time, when stretched and played a lot. the hairs become smoother and smoother. This causes it to slip and the player will tend to rosin the bow so much it becomes scratchy and rough without producing good quality of tone.

If you find yourself using more and more rosin than usual and not getting enough grip on the strings it is time to get a rehair. If you practice a lot (4 of 5 hours a day) you may need to get your bow rehaired every couple of months. For most people every 6 months to once a year is enough if all or most of the hairs are still intact. Don’t attempt to wash the hair as you can damage the bow and it won’t do much good as it is the smoothness of the hairs that cause the slipping.

Another reason to have the bow rehaired is if the hair becomes too long or too short. In general the hair becomes too long when it is used for a while and becomes stretched. The hair will not grip the string as well when it is too stretched. In the winter the hair tends to become too short and in the summer too long as a result of temperature and humidity changes in these seasons. If the hair becomes too long relatively soon after it has been rehaired it can be shortened by the person who rehaired it or someone who is experienced in bow rehairing.

If you are having trouble tightening or loosening the hair don’t force things. The screw or eyelit may be worn. Bring the bow in to a repairman.