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Springiness of bow related to the amount of hair.


Andreas Preuss
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A while ago, a customer asked for an super extra plus amount of hair on his violin bow. And to make a long story short, after it was done the bow didn't function. The bow was not only difficult to tighten (as expected) but it was difficult to control for bowing techniques which need some springiness 

Anyway, now a few month later I was rethinking all bow rehair aspects and besides the quality of the hair it should be possible to adjust the amount of bow hair to get some ideal equilibrium between bow stick and hairs. 

To sum it up: is there a recipe or procedure to determine the best amount of hair for a bow? The easy equation seems to be: stiff stick needs more hair than a weak stick. 

How to determine the right amount? 

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The amount of hair needed is dictated by the mortise in the head of the bow. Since the size of the mortise isn’t standardized, the amount needed varies from bow to bow. A hair gauge helps get an idea of the average hank, but you have to adjust with different bows to avoid crowding the head. Too much hair makes a bow feel dead. 

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Depends on what you need. Too little hair on a stiff stick and you will have a very weak, bouncy bow with a thin, cold sound (hair will not effectively engage the string because it will be under too much tension). If you go the other way, it will be gross as you experienced.

 

It is also partially dictated by how much hair the bow can physically hold, as mentioned above.

 

 

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Depends also on how good rhe bow is. The best bow in our house was rehaired a few years ago with what I think was around 150 hairs. It never got as powerful or focused tone as it had in the past. I rehaired it myself a few months ago and used 180 hairs which is what the norm was previously. Volume and tone quality returned.

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10 hours ago, Deo Lawson said:

Depends on what you need. Too little hair on a stiff stick and you will have a very weak, bouncy bow with a thin, cold sound (hair will not effectively engage the string because it will be under too much tension). If you go the other way, it will be gross as you experienced.

 

It is also partially dictated by how much hair the bow can physically hold, as mentioned above.

 

 

I am thnking of some refinement for the best bows coming  to my shop. I think often customers don't quite realize that the ammount of hair in their bow iis not really what the bow needs to perform best. Of course we are just twising the stick to get an idea if the bow to be rehaired is rather stiff or rather supple, but I think this can be refined to some degree.

 

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2 hours ago, Fiddler45 said:

Depends also on how good rhe bow is. The best bow in our house was rehaired a few years ago with what I think was around 150 hairs. It never got as powerful or focused tone as it had in the past. I rehaired it myself a few months ago and used 180 hairs which is what the norm was previously. Volume and tone quality returned.

That's more or less the direction I am thinking. And in your exo the sample thats actually 20 percent more hair!

Counting hair is certainly the precisest way to do it if the actual diameter doesn't change from one bulk hair the next. 

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There are quite a few factors when tweaking rehairs to alter the performance of bows. There are excellent teachers here that could offer a few suggestions and plenty of warnings. There are more exceptions than rules.

Most customers ideally would like the same, predictable amount of hair, similar in quality, spread the same way. For my own rehairs, extra hair has never been a good idea. The abstract that has helped was that the structure of the bow itself vibrates along with the hair. Do what you will with the info. My experience has been that too much hair feels and sounds inefficient, made worse by sticky rosin and humidity. Imagine a Glasser German Bass bow with too much hair and too much Pop's rosin...  Anyway, it appears that adding tension also "tunes" some finer bows into a particular response and dynamic behaviour making it way more interesting when leaning into the bow.  

For student bows, i do add bit more hair. For synthetic student bows, I will likely see the bows again. I do spread a tiny bit of weak glue on a facet if i replace with a wood plug. The original plastic inserts are mostly not worth salvaging.

This suggestion borders on malpractice but have done it for my own bows and a few associates bows. If one has a firm grip on the bow, this procedure is less useful if not useless, so do not try it. I play with a very light hold on most of bows so will make an effort to feel and hear changes as they occur. When i use a firm grip or pull up into the frog to produce a more intense ( or sometimes flat hair ) sound, my hand is less sensitive to the changes within the bow though there are sonic changes. 

Certainly i am not the only person who does this but unless one has a degree of expertise and an elevated understanding of how the particular bow behaves at various tensions, it is not suggested. It is a simple operation starting with a fine ribbon like rehair of a known quality, quantity and thickness. Play on the new rehair for a few days and find the optimum tension for play with the desired rosin. Then evenly knife/ trim off 5 - 10 hairs at the tip, then frog ( the same hairs!! ) and relocate the optimum tension. Play until all desired parameters are tested, then trim off another 5 - 8 hairs. Repeat cycle. 

My French bows, which have quite a bit of lateral movement, generally sound more clear with fewer hairs but also more frequent rehairs.

If after the first trim, the player notices no difference, do not continue with the experiment. Some bows behave very well throughout its playing range and may not change significantly in character. One of my teacher's Nurnberger had virtually no sonic effect until it started to sound weak. There was a particular amount of hair where a ricochet was very responsive and clear. This particular bow was very easy to get a nice substantial sound and any noticeable change was mostly a particularly light feel in the hand. 

Be careful, a knife can easily nick many hairs at once. 

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23 hours ago, The Violin Beautiful said:

The amount of hair needed is dictated by the mortise in the head of the bow.

To me the size of the ferrule is more important than the size of the head mortice because you can adjust the amount of space in the head by changing the size of your block, but the ferrule size is always the same.

I see many old french bows that have a wide ferrule but a small mortice in the head. If you use a small amount of hair in these bows, the hair is too thin at the ferrule and will tend to break. You can compensate for this by leaving a little more space at the head block that will allow for the extra hair needed at the ferrule.

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The hair gap needs to be just the right size to accommodate the hair. If it’s left too big, the tip plug won’t be stable unless it’s fitted too tightly or just glued in (neither of which is appropriate). The hair won’t sit properly in the head and will clump up the way it does at the frog without a spread wedge.

A good spread wedge will spread the hair very well and allow for a fairly wide ferrule before there’s any issue. Don’t underestimate the ability of the humble spread wedge!

Some makers like Tubbs went to considerable length to design their frogs in a way that made it harder to put too much hair in, as over-hairing is such a common issue. 

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what you say is true but if the the hair is spread to thin at the ferrule an aggressive player will break  hairs sooner than they would like. I think we can all agree that the "correct" amount of hair is the ideal it's just that I think using the head mortice size as the guide to the amount of hair you use, can sometimes lead to undesired results. The truth is there are many factors that should be considered when trying to determine the "correct" amount.

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On 12/12/2019 at 11:23 AM, Andreas Preuss said:

A while ago, a customer asked for an super extra plus amount of hair on his violin bow. And to make a long story short, after it was done the bow didn't function. The bow was not only difficult to tighten (as expected) but it was difficult to control for bowing techniques which need some springiness 

Anyway, now a few month later I was rethinking all bow rehair aspects and besides the quality of the hair it should be possible to adjust the amount of bow hair to get some ideal equilibrium between bow stick and hairs. 

To sum it up: is there a recipe or procedure to determine the best amount of hair for a bow? The easy equation seems to be: stiff stick needs more hair than a weak stick. 

How to determine the right amount? 

Doesn't it seem reasonable,  that if amount of hair in the ribbon is critical,  one should ask whether one wants the ribbon at the point of transition away from pure elastic ?

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3 hours ago, Johnmasters said:

Doesn't it seem reasonable,  that if amount of hair in the ribbon is critical,  one should ask whether one wants the ribbon at the point of transition away from pure elastic ?

This is a good point.  The amount of hair does not mean a hill of beans if the rehair is not good.  A well rehaired bow should have a feeling of solidity as one plays....engaging the elasticity of more hair as the player “pushes” the bow.  If the hair does not have this linear resistance the bow feels mushy even if the appropriate amount of hair is used.....as analogy....it would be like having a discussion about the width of a soundpost without being able to make it fit.

 

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