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Bow Hair Weight?Bow crack....


Ray Weaver
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For anyone at all...1) I am curious as to how much weight an average rehair might add to a bows weight. I noticed a bow on eBay which supposedly weighed 46 grams (without hair) - this seems to be light to an extreme - surely bow hair couldn't add enough to make this bow fall into the generally accepted area of bow weight, or could it? Thanks for any answers.

2) I am also looking at a bow which has a hairline crack running thorough the ivory at the tip about 75% of the way up the head of the bow (On the other side the bow has a small chip reglued in a seemingly competent manner). Realizing that this constitutes major damage I wonder how much this condition might devalue the bow? Would it be the same as if the crack had gone all the way through and then the bow repaired (a la HKV's Sartory?) The bow is a F.N. Voirin and it plays wonderfully, better than my other bows, a Charles bazin, a C. Thomassin, and a Pajeot school bow so I'm going to get it in any case at the price $2500,00 just for playing qualities. I'd pay that even if I knew it would explode in five years just for the pleasure of playing it!

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Michael,

I find that very useful information - so, if a rehair used 120 hairs instead of 155, the hair would weight 4.25 grams.

Some "soft" bows (like many Voirins) will do better with less hair (like mine does).

I recently had three Arcus bows rehaired, and they are not playing as well anymore. I tried working rosin into them differently - and that helped a good bit - but not completely. Then I realized that the amount of hair used in them was fairly standard for regular bows. I had them weighed yesterday and they came up 2 grams short of the published spec - with the violin bow weighing only 51 grams instead of the published 53 g and the viola and cello bows also being exactly 2 g "short." So - back in the shop they are now for the right amount of hair - for them. (If I work through what you have contributed Michael (realizing that bow hairs do come in diferent thicknesses) If my Arcus violin bow now has 120 hairs, its bare weight would be 51-4.25 = 46.75g, pretty close to Ray's observation. To get it up to 53 grams would require about 176 hairs, or about 13% more than Michael's standard hank of hair.)

Most of my life - I found that my standard pernambucos bows were being rehaired with too much hair (at least I know that now). You might think this is a nice extra benefit - since it will take longer for enough hair to break that you need a rehair. But it doesn't work that way. For one thing, some bows will bend to the side when tightened after only a few hairs break. But the worst thing is that the bows play mushy and none of the fine features the maker built in will show in their use - even the finest bows in the world.

The amount of hair is optimized when the interplay of the stick and hair work together in just the right combination. The softer the stick, the less hair the bow can tolerate. The actual tension in each individual hair is mathematically equal to the value tension in all the hairs (that balances the tension in the stick) divided by the number of hairs. The sound qualities the bow contributes to the instrument are directly linked to the value of tension in each hair (I'm convinced of this). So - a (soft) Voirin (in general) requires few hairs to bring out the best sound as well as the best playing qualities of the bow. An Arcus, which is a very light and very stiff bow, on the other hand requires about all the hair it can hold - because with it, the individual hairs must still have enough tension, but they must still balance the very stiff stick - which will not contribute its flexibility in the same way as the Voirin.

(I think I went too far afield on this one - but it is somewhat related - in my mind, anyway.)

Andy

[This message has been edited by Andrew Victor (edited 12-02-2000).]

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hmmm...This has got me to thinking about bow hairs. It seems to me that all of the hairs will not be under the same tension except on an ideal bow (at least I presume it would be ideal). As I slack off the tension on my bow, I can observe a half-dozen or so hairs fall slack well before the others. It seems unlikely those would not be under a full share of the tension when it is tightened. Wouldn't those hairs that are shortest and least elastic be carying a greater share of the total tension? I wonder how this disparity in hair length & tension contributes to the sound and playability of the bow? Maybe this is one reason rehairing a bow is not as easy as it might sound.

I have never heard anyone mention hair tension in quantifiable terms. Is this ever actually measured? It seems to me there ought to be some device for this like those little clamp-on gadgets for measuring tension in v-belts used in automobiles and air conditioning equipment.

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Mark - they are all full-width hairing - to the sides of the ferrule - at least when done well (either from the Arcus factory) or by a top-notch shop. Although I can remember years ago seeing rehairs (on other people's bows) that looked preety skinny to me - and I would always inquire where they had been done so I could avoid those shops.

Oldbear: Good question? I've had some rehairs that were like that, but I did not notice any partcular flaw in the playing of the instrument. My Coda violin bow looked kind of that way after I first had it rehaired - yet it played better than ever (I should note that the rehairs did look like thicker individual hairs, but fewer of them, than the original had.) In fact - it may be a natural phenomenon and all come out "in the wash," But certainly, by the time the bow is tightened, all the hairs are under tension - and if they are within their individual elastic limits at least some of them are just right; maybe thats's all it takes. Some of those touching the strings will be just right for best friction and some of them connected to the ends of the bow will be just right to convey proper damping in the stick back to the hairs that are incontact with the strings. If there are too many hairs, it is possible that none of them gets to the right tension until the stick has been straightened too much, and then its restoring forces behave differently and the bow is not optimal for other reasons.

Andy

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Andy, I think you are right on the mark here. This would also explain HKV's preference for the 'organic liveliness' of old pernambuco bows, in that they derive their sound qualities from their ability to get sound out of fewer hairs and lower total tension (all hairs combined.)

Just curious, Andy--how does the width of the ribbon of hair compare between the Arcus and the Voirin? Any difference?

quote:

(edited)

The amount of hair is optimized when the interplay of the stick and hair work together in just the right combination. The softer the stick, the less hair the bow can tolerate. The actual tension in each individual hair is mathematically equal to the value tension in all the hairs (that balances the tension in the stick) divided by the number of hairs. The sound qualities the bow contributes to the instrument are directly linked to the value of tension in each hair (I'm convinced of this). So - a (soft) Voirin (in general) requires few hairs to bring out the best sound as well as the best playing qualities of the bow. An Arcus, which is a very light and very stiff bow, on the other hand requires about all the hair it can hold - because with it, the individual hairs must still have enough tension, but they must still balance the very stiff stick - which will not contribute its flexibility in the same way as the Voirin.

(I think I went too far afield on this one - but it is somewhat related - in my mind, anyway.)

Andy

[This message has been edited by Andrew Victor (edited 12-02-2000).]
[/b]

[This message has been edited by Mark_W (edited 12-02-2000).]

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