I know most people advocate frequent re-hairing bows claiming that, beside breakage, bow-hair gets worn and less supple with use resulting in erratic grip of the string and a clouded sound. While it is indisputable that hair does break and get dirty I’d offer that there are many commonplace misconceptions. In fact any hair yet to go on a bow had become greasy, worn and polished smooth when it was still on the horse swatting flies. Evidence for this is easily found in the fact that the tip-end is already 40% thinner and many years older than the root-end when it is originally shipped in bundles out of Mongolia.
The Mongolian horse-hair-trade is very secretive so we can only surmise that most bundles contain a mix of many different individual horse's hair whose average shelf-age must vary.
For playing a musical instrument the friction needed to excite a string is actually caused by the rosin attached to the hair rather than by the hair itself. Added to the friction to the string each individual hair must undoubtably gradually wear thinner by the friction caused by the neighboring hairs in a ribbon that is constantly changing shape as it traverses across the string. As on the horse, each hair remains sufficiently uniform in structure all the way through and functions in the same manner until it breaks.
The myth of the ‘loss of scales' is easily dispelled by direct observation of well used bow-hair with a microscope.
Most hair breakage on a bow is caused by a combination of hasty poor selection and the clipping effect of the hair being captured between the string and the wooden bow-stick.
The very real problem is muck, the accumulation of a caked mixture of rosin, dust and fatty substances. Some hard working musicians using my bows have been playing practically daily without a re-hair for 20 years (and counting...) while only regular cleaning it with alcohol. This is no longer surprising if you consider one can find crafted horsehair objects (bags, saddles, carpets, etc.) in museums that are hundreds and even thousands of years old which have remained supple and strong.
I guess it became a tradition over the years to re-hair bows without choosing the hair too carefully so violin shops would frequently see their clients.
Cleaning the hair
Clean the hair with a clear colored toothbrush and 96% alcohol brushing down to a white cloth. Carefully avoid soaking the end-wedges so that they don't swell up. You can also easily wipe clean unvarnished Snake-wood sticks with a cloth dampened in alcohol. Be very careful though to not damage Pernambuco-wood bows, which are varnished with shellack which dissolves in alcohol. After having cleaned the hair and bow-stick one can always oil the wood if it appears 'dry' (carefully avoiding the hair!) with a touch of sweet almond oil, which is available at any chemist.
Re-hairing
There is a tradition the world round to re-hair bows like a racing-car-pit-stop. This philosophy I don't share. It takes me at least 4 hours to re-hair a bow, (but then I've only been doing this for 40 years). Luckily my wife has taken upon herself to preserve my sanity and helps by saving me half the time as she carefully chooses the hair in my stead. Israel Castillo has joint the efforts recently. Thank you!
Even though we use the very best available unbleached Mongolian hair, we only find about 10 to 15% to be trustworthy to be installed on an ambitious musician's bow.
I do understand that if one would have to re-hair 10 bows in a days work one could not possibly apply these standards.
To re-hair your bow you must find somebody willing to devote the time required to do it conscientiously (you could help by purchasing a bundle of hair and learn to simultaneously meditate by choosing your own bow’s hair!). Most violin makers are very patient, careful and skilled workers but they can't possibly afford to avoid a hasty job if they are forced to ask the ‘competitive’ current price for a Drive-In-McDonalds-style-re-hair. You could instead offer to compensate them properly for their quality, time and material expenses.
Luis Emilio RodrÃguez Carrington, December 2017
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