Bow Quote & Question from Paulo’s blog

[PhilipKT]

“After eighty years the sound of this bow has a speed superior to 5500 m/s; a miracle to a bow from 1930.”

This quote Is about a Sartory bow. I have no idea what this quote means, and I hope someone can explain it. What does Paulo mean by referring to the bow speed? Sound projection would be more a function of the instrument wouldn’t it?

BTW, I love Paulo’s blog, Although he kind of pooh-poohs Gillet. But that’s OK…

[GoPractice]

Just a link to a site:

http://www.lucchimeter.com/sound-velocity-in-bow-making/

Can search relative posts... a friend recently suggested i purchase one. But not sure the bows i make for myself needs all this added data, though data is cool. The meter is rather pricey. 

[martin swan]

Whether a high Lucchi reading is a good thing in a bow is very much a matter of debate ...

[PhilipKT]

56 minutes ago, martin swan said:

Whether a high Lucchi reading is a good thing in a bow is very much a matter of debate ...

So Paulo’s comment is a reference to the lucchi Meter reading of the bow stick? I think that identifies bow stiffness right? And if that’s true, why would the age of the bow make a difference?

[martin swan]

Not stiffness, speed of sound transmission ...

Basically since the invention of the Lucchi meter everyone goes for as high a Lucchi rating as possible.

Before people had Lucchi readings this wasn't an important factor in bow design 

[PASEWICZ]

1 hour ago, martin swan said:

Not stiffness, speed of sound transmission ...

Basically since the invention of the Lucchi meter everyone goes for as high a Lucchi rating as possible.

Before people had Lucchi readings this wasn't an important factor in bow design 

Yup, actually they had a Lucchi Meter, they called it a knuckle.

[Emilg]

12 hours ago, martin swan said:

Not stiffness, speed of sound transmission ...

Basically since the invention of the Lucchi meter everyone goes for as high a Lucchi rating as possible.

Before people had Lucchi readings this wasn't an important factor in bow design 

Isn't speed of sound also a measure for stiffness? From wiki on speed of sound:

Quote

Thus the speed of sound increases with the stiffness ..

I also thought wood gets more stiff when aging, so a Lucchi reading was probably not the same 100 years ago.

[ctanzio]

12 minutes ago, Emilg said:

Isn't speed of sound also a measure for stiffness? From wiki on speed of sound:

I also thought wood gets more stiff when aging, so a Lucchi reading was probably not the same 100 years ago.

Sound speeds and the elastic moduli of a material are related by the physics of how materials deform. Since an elastic modulus is a measure of how much a material deforms when stressed, it is a measure of "stiffness".

I put stiffness in quotes because there are factors other than the elastic moduli. The geometry of the bow greatly affects the "stiffness". For example, suppose a bow maker was aiming for some target "stiffness". By selecting a wood with a high sound speed, it implies the wood has a high elastic modulus. Therefore, the bow can be made thinner than with a wood that has a lower sound speed, but still achieve equal stiffness between the bows. So the high sound speed bow could be made lighter than the low sound speed one.

Perhaps lightness is a desirable characteristic in a bow. I don't know since every bow I have ever tried feels like a feather in my hands (flexes massive biceps). Certain bow techniques, like spiccato and sautille, are affected by both the weight of the bow and its stiffness.

Typically, the elastic moduli of wood, and most other basic structural properties, change little over time unless there is some fundamental breakdown in the wood structure. This is a difficult area to study because of the wide variation of material properties among trees, even if they are from the same wood species.  But wooden structures that are protected from severe environmental aging affects can last for many centuries and still stand as strong as the day they were completed. Someone like Don Noon, who can artificially age wood samples and measure the mechanical properties of a single sample over time-of-aging might be able to speak to this.

Sound speed may change over time because it is also a function of the density of the wood. Normal wood aging causes a release of "extractives", like oils. Hemicellulose content also  shows a significant decrease over time. As the density of the wood decreases, its sound speed will increase, even if its elastic moduli remain mostly unchanged.

Aged wood also shows a marked decrease in sound dampening, mostly due to the reduction in hemicellulose. I suspect this accounts for the loudness and high pitched ringing of old instruments. Perhaps Strad's secret was to build violins that could survive for a couple of centuries.

 

[Emilg]

1 hour ago, ctanzio said:

Sound speeds and the elastic moduli of a material are related by the physics of how materials deform. Since an elastic modulus is a measure of how much a material deforms when stressed, it is a measure of "stiffness".

I put stiffness in quotes because there are factors other than the elastic moduli. The geometry of the bow greatly affects the "stiffness". For example, suppose a bow maker was aiming for some target "stiffness". By selecting a wood with a high sound speed, it implies the wood has a high elastic modulus. Therefore, the bow can be made thinner than with a wood that has a lower sound speed, but still achieve equal stiffness between the bows. So the high sound speed bow could be made lighter than the low sound speed one.

Perhaps lightness is a desirable characteristic in a bow. I don't know since every bow I have ever tried feels like a feather in my hands (flexes massive biceps). Certain bow techniques, like spiccato and sautille, are affected by both the weight of the bow and its stiffness.

Typically, the elastic moduli of wood, and most other basic structural properties, change little over time unless there is some fundamental breakdown in the wood structure. This is a difficult area to study because of the wide variation of material properties among trees, even if they are from the same wood species.  But wooden structures that are protected from severe environmental aging affects can last for many centuries and still stand as strong as the day they were completed. Someone like Don Noon, who can artificially age wood samples and measure the mechanical properties of a single sample over time-of-aging might be able to speak to this.

Sound speed may change over time because it is also a function of the density of the wood. Normal wood aging causes a release of "extractives", like oils. Hemicellulose content also  shows a significant decrease over time. As the density of the wood decreases, its sound speed will increase, even if its elastic moduli remain mostly unchanged.

Aged wood also shows a marked decrease in sound dampening, mostly due to the reduction in hemicellulose. I suspect this accounts for the loudness and high pitched ringing of old instruments. Perhaps Strad's secret was to build violins that could survive for a couple of centuries.

 

Thanks ctanzio, so the wood properties would not have changed that much in 100 years.

I understand that a fungi treatment can speed up the hemicelluloses breakdown. Some years ago a violin from treated wood beat a Strad in a blind test. I don't know if makers here have experimented with that, but that one is on my todo list

 

[sospiri]

1 hour ago, Emilg said:

Thanks ctanzio, so the wood properties would not have changed that much in 100 years.

I understand that a fungi treatment can speed up the hemicelluloses breakdown. Some years ago a violin from treated wood beat a Strad in a blind test. I don't know if makers here have experimented with that, but that one is on my todo list

 

Hmm, the fungi treatment has been debunked though hasn't it?

2 hours ago, ctanzio said:

Sound speeds and the elastic moduli of a material are related by the physics of how materials deform. Since an elastic modulus is a measure of how much a material deforms when stressed, it is a measure of "stiffness".

I put stiffness in quotes because there are factors other than the elastic moduli. The geometry of the bow greatly affects the "stiffness". For example, suppose a bow maker was aiming for some target "stiffness". By selecting a wood with a high sound speed, it implies the wood has a high elastic modulus. Therefore, the bow can be made thinner than with a wood that has a lower sound speed, but still achieve equal stiffness between the bows. So the high sound speed bow could be made lighter than the low sound speed one.

Perhaps lightness is a desirable characteristic in a bow. I don't know since every bow I have ever tried feels like a feather in my hands (flexes massive biceps). Certain bow techniques, like spiccato and sautille, are affected by both the weight of the bow and its stiffness.

Typically, the elastic moduli of wood, and most other basic structural properties, change little over time unless there is some fundamental breakdown in the wood structure. This is a difficult area to study because of the wide variation of material properties among trees, even if they are from the same wood species.  But wooden structures that are protected from severe environmental aging affects can last for many centuries and still stand as strong as the day they were completed. Someone like Don Noon, who can artificially age wood samples and measure the mechanical properties of a single sample over time-of-aging might be able to speak to this.

Sound speed may change over time because it is also a function of the density of the wood. Normal wood aging causes a release of "extractives", like oils. Hemicellulose content also  shows a significant decrease over time. As the density of the wood decreases, its sound speed will increase, even if its elastic moduli remain mostly unchanged.

Aged wood also shows a marked decrease in sound dampening, mostly due to the reduction in hemicellulose. I suspect this accounts for the loudness and high pitched ringing of old instruments. Perhaps Strad's secret was to build violins that could survive for a couple of centuries.

 

So Paulo's quote was misinformation? The Satory bow had a naturally high speed of sound?

 

20 hours ago, PhilipKT said:

“After eighty years the sound of this bow has a speed superior to 5500 m/s; a miracle to a bow from 1930.”

This quote Is about a Sartory bow. I have no idea what this quote means

It doesn't make sense. If the sentence was re-written, then maybe it would?

This eighty nine year old bow has a speed of sound superior to 5500m/s, a miracle bow from 1930.

[Emilg]

28 minutes ago, sospiri said:

Hmm, the fungi treatment has been debunked though hasn't it?

 

I missed that part

Searching the archives i found a remark by Bruce Tai:

Quote

By no means do I promote the idea of artificial aging by baking, boiling, UV, acids, bases, and fungi. I think these treatments are damaging and will degrade the wood in a very different way from natural aging.

that might be the problem for many of the treatments after short term success...

[PhilipKT]

Nagyvari was a local VM who came up with a method of aging the wood. It supposedly worked well but I haven’t heard anything more from him for years.

[ctanzio]

3 hours ago, sospiri said:

So Paulo's quote was misinformation? The Satory bow had a naturally high speed of sound?

It is possible that over 80 years enough extractives were released and hemicellulose degraded to cause a measurable drop in density of the bow wood. This could account for an increase in sound speed.

But from the quote it was not obvious that the sound speed was measured at the time the bow was made, and then 80 years later. The quote suggests that bows made in the 1930s had lower sound speeds at the time they were made, but no evidence is offered that sound speed was even measured in the 1930's.

There is insufficient information to draw any conclusion with scientific validity. Since I am a natural born skeptic, I would say it proves someone has a bow that is at least 80 years old, and it has a sound speed. >grin<

Accelerated aging methods are fraught with pitfalls. People with insufficient training in aging methods frequently subject the wood to processes that do not occur naturally or that fundamentally change the structure of the wood in a way that does not occur over centuries of natural aging. Technically they are not aging the wood, but rather processing it in some way with the hope of getting better performance.

Edited September 18, 2019 by ctanzio
typo

[FiddleDoug]

Stiffness and speed of sound would be two different things .A 30" piece of 2x4 is going to be a whole lot stiffer than a 30" bow, but since the 2x4 is pine, the speed of sound would be a lot lower.

 

[fiddlecollector]

As far as i know the best pernambuco has a higher content of extractives than a poorer quality wood .Ive also heard lucchi readings are supposed to go down with age. So a Sartory with at present has a 5500 m/s reading may have started with maybe 5800 m/s.  But there is a lot of conflicting research. Also lucchi meters are expensive to play around with  to do your own research unless you can borrow one.

PDF attached about extractives in bow wood.

IAWA J 33 (2) 141-149.pdf

[Emilg]

12 hours ago, FiddleDoug said:

Stiffness and speed of sound would be two different things .A 30" piece of 2x4 is going to be a whole lot stiffer than a 30" bow, but since the 2x4 is pine, the speed of sound would be a lot lower.

 

Hi Doug, it's more about relative stiffness, so the stiffness with equal dimensions. Higher speed should also give higher stiffness.

Would damping play a role in bows? Damping will decrease with age.

[Jim Bress]

I was at a bow makers shop last weekend.  I was looking over a bunch of blanks he had out on his bench, all marked with density and speed of sound.  Thinking of some of Don's past experiments I asked him what he thought about speed of sound for bows.  He said he's been recording them for a long time but has yet to be able to predict the quality of a bow based on speed of sound.

[PASEWICZ]

1 hour ago, Jim Bress said:

I was at a bow makers shop last weekend.  I was looking over a bunch of blanks he had out on his bench, all marked with density and speed of sound.  Thinking of some of Don's past experiments I asked him what he thought about speed of sound for bows.  He said he's been recording them for a long time but has yet to be able to predict the quality of a bow based on speed of sound.

It is far easier to predict the quality of a bow based on the choice of the bowmaker than the Lucchi of the wood.

[GoPractice]

The thing about measuring devices is determining how one decides to use them. Even the use of the knuckle, at many levels, is different in the hands of a novice compared to that of a professional or an artist.

There are bowmakers who are or should be considered artists, rather than professional bowmakers. The difference is in how they create a bow out of an interesting piece of Pernambuco they have selected. Workmanship is one thing, as we can learn to visually assess such qualities over time studying books and looking at bows. But for most of us who do not work in a shop, we listen to discussions and listen to an assortment of advice from friends and associates. We can trust our eyes, perhaps too much.

An interesting piece of Pernambuco is a piece of wood that a maker believes is worthy of a new life beyond it's existing on a shelf. The meter helps some determine, if there is a pre-build value for potential buyers. It is part of preparing for a sale. I would also guess, that buyers might feel better if a maker had a meter? and the data logged for the stick might be of some interest generations from now. Otherwise, the grain, the color, the density, the run out, its resilience, its resonance or its sheer charm is why a maker might choose a particular stick. The meter, for the Artisan, would likely not make the list. I am not saying it that it is irrelevant, but rather, like our sight might blind us from the observational sounds of planing and the feeling of the stick if it were in the maker's hands. They would know. Know what to do. Or not do. They have handled thousands of bows in training and in study. While perhaps on a CNC machine, the set up of the stick and finding the ideal chip and clear rate would likely be more important as the roughing out stage and the duration of the finish work would be limited. Or maybe not. Perhaps an insigthful maker can fell these subtleties in the final mm of work.

But the practical part of life is that a young maker can not house several hundred blank, or for a professional maker it is important to be able to sell bows in a trending markets. The Lucchi meter, for the price of a dozen fairly nice blanks can afford some sense of security and possible outcomes. Does it insure outcomes? i would like to suggest: probably less likely for most, but for others it might be very important. But i am uncertain of this. I am sure there are some makers who find it to be a very important tool. 

Players are also a vast sea of unknowns. Bony hands vs fat hands, slender vs heavy arms, good posture vs adaptive caressing ( have some of you seen Gaelynn Lea perform? listen to her - the tone, is it glowing? )...  i can probably adjust my playing for high m/s sticks. I do. My last Parisian bow, expensive and purchased brand new with no prior chance to play, is really stiff and light. My students generally love it ( predictable spiccato and power ) but i struggle to achieve what i consider my range of sound. It is dynamic and where you point it, it goes. But delicate? dreamy? It is unforgiving and with about 200 hours of use ( 20 of which are mine ), i can sound amateurish if not unsure, trying to determine how to best play the bow.

This might be the stereotypical dilemma of orchestral vs chamber vs solo music playing. Generally, in orchestral work it is to sound uniform; Chamber music requires more nuance and expressiveness, while solo work often is about expressing individuality. Among the finer Lucchi meter using bowmakers ( that i know ) the buyers are usually younger conservatory level players. Perhaps these are the best customers for the best type of tools required in school? Certainly the pricing is more reasonable than a retail French bow. Then after getting a professional position, they are able to acquire a Sartory or similar level bow? It is not intended to steer these generalizations this direction, but the orchestral sound has changed in the past 20 years, arguably for the better while others seriously miss the Ormandy ( Philadelphia - Angel? ) or Szell ( Cleveland - CBS ) or even the more digital Solti ( Chicago - London ), restored digital - Reiner ( Chicago - RCA ), or the fully modern Jansons ( Oslo - Chandos ) sounds? They played Vuillaume era bows. I still will not pass up the ever more rarer opportunity to play this era bow. It is eye and ear opening ( if possible. ) Anyway, the by product of the use of a meter, might be for a stronger - not necessarily a finessed - stick, as i assume the power of the marketplace.       

The reason i would like a Lucchi meter is in trying to determine if it is possible to measure a "played out" bow. It would be interesting to overplay a bow in person or on a machine and measure to see if there are any changes as the bow becomes subjectively softer in either feel or sound. There are vigourous players out there and some bows do not survive. I can only assume that the integrity of the wood has some how deteriorated and if it could be measurable. My thought was that if there were damage across the grain the m/s would be slower or not read as a high output due to the loss in "heat" energy. I have tried coupling a vibrating element to a frog and measured the output at the tip with a microphone. It is fun just to goof off, but the vibrating element starts to roll off quickly around 1.2k ( 3rd position on e-string ) due to the bow's mass, and to the best of my knowledge the coupling is not perfect and the assembly behaves unpredictably. The fulcrum was near the thumb grip, but some have argued the use of the balance point. So very little is of value but goofing off is fun. Sorry if there are too many thoughts in this narrative.

  

[sospiri]

On ‎9‎/‎18‎/‎2019 at 8:13 PM, ctanzio said:

It is possible that over 80 years enough extractives were released and hemicellulose degraded to cause a measurable drop in density of the bow wood. This could account for an increase in sound speed.

But from the quote it was not obvious that the sound speed was measured at the time the bow was made, and then 80 years later. The quote suggests that bows made in the 1930s had lower sound speeds at the time they were made, but no evidence is offered that sound speed was even measured in the 1930's.

There is insufficient information to draw any conclusion with scientific validity. Since I am a natural born skeptic, I would say it proves someone has a bow that is at least 80 years old, and it has a sound speed. >grin<

Accelerated aging methods are fraught with pitfalls. People with insufficient training in aging methods frequently subject the wood to processes that do not occur naturally or that fundamentally change the structure of the wood in a way that does not occur over centuries of natural aging. Technically they are not aging the wood, but rather processing it in some way with the hope of getting better performance.

I think I should be sceptical too. The bow looks like it hasn't been played much. Maybe it's very nice to look at, but not so good to play?

[martin swan]

8 hours ago, sospiri said:

I think I should be sceptical too. The bow looks like it hasn't been played much. Maybe it's very nice to look at, but not so good to play?

This is a common fallacy.

To disprove it all you need to do is to consider the opposite ie. that something in terrible condition must necessarily perform very well and for that reason have had excessive use.

[Felefar]

What about compressional anisotropy? Is the Lucchi meter always used to measure speed of sound along the grain, or are users sloppy in the directionality? Speed of sound  is one important measure in my work (oil geologist, specialising in wellbore log interpretation),  and velocity anisotropy is one of the things we always have to watch out for.

 

We tend to state velocities in microseconds per foot, one of the very few non-metric measures we can’t seem to get rid of.

[sospiri]

14 hours ago, martin swan said:

This is a common fallacy.

To disprove it all you need to do is to consider the opposite ie. that something in terrible condition must necessarily perform very well and for that reason have had excessive use.

I don't see the logic there. It could have had very careful owners who played it a lot. Or it could have been kept by collectors who barely used it.

But I will never know how it plays, or any other of his collection. I do know that some very ugly bows can play well though and I'm fascinated by the fact that every bow plays differently, just like instruments. For the past few days I've been testing all my bows and one of them is very interesting. It looks like light coloured Pernambuco (no guarantee, I know) it will weigh 53 grams when re-haired (again, no guarantee of superiority)  Buts when I tap it it goes pzzinnnngggggggggggggggggggggggggggggggggggggggggggggggggggg. I'm hoping that does mean something?

I would like to learn the art of re-hairing to find out.

[sospiri]

13 hours ago, Felefar said:

What about compressional anisotropy? Is the Lucchi meter always used to measure speed of sound along the grain, or are users sloppy in the directionality? Speed of sound  is one important measure in my work (oil geologist, specialising in wellbore log interpretation),  and velocity anisotropy is one of the things we always have to watch out for.

 

We tend to state velocities in microseconds per foot, one of the very few non-metric measures we can’t seem to get rid of.

Some information here about speed of sound across the grain as well as along the grain

 

https://www.vermontviolins.com/faqs/2018/7/26/pernambuco-vs-carbon-fiber-bows

[martin swan]

7 hours ago, sospiri said:

I don't see the logic there. It could have had very careful owners who played it a lot. Or it could have been kept by collectors who barely used it.

 

That's my point.

Condition is no indicator of playing quality either way.