Mechanical-acoustic properties of pernambuco

December 13, 2022, 4:32 AM · It's a topic of much discussion but little or no objectively established fact.

December 13, 2022, 6:56 AM · Although it is 11 years old, this paper, which you can find by googling it, will get you to parts of your question and into a great list of references to help your search:

The violin bow: Taper, camber and flexibility, Colin Gough

December 13, 2022, 12:03 PM · Also read Andreas Grütter's "A Bow On The Couch". You will then have a vague idea of how wood stiffness and weight interact with bow design.

What you'll then need to know is that the missing part of the story is damping, which is the specific way different woods dissipate vibration energy.

Somewhere there's been some discussion of pernambuco's uniqueness in this regard. You might find reference to it over at Maestronet.

Edited: December 13, 2022, 3:16 PM · 90% of what you will read on this subject is unmitigated rubbish. The other 10% has a chance at being reputable science.

That reminds me of a line from the movie, Dirty Harry. Clint Eastwood's character has the bad guy on the ground trying to reach for his gun. Callahan wonders aloud whether he's taken five shots or six with his own pistol (a huge revolver), and he says,

"So the question is, do you feel lucky? Well, do ya, punk?"

December 13, 2022, 10:20 PM · The violin is one of things where the more you research, the less you know. The amount of nonsense people have spewn out there is astonishing. I think some tactile experience of working with wood and making bows is needed in order to start to discern what is plausible and what is fantasy.

Edited: December 14, 2022, 2:11 AM · Paul - this is the conclusion I came to as a student of psychology half a century ago. I'm sure the other students felt the same but we couldn't agree on which 10% to believe.

December 14, 2022, 5:47 AM · Leveraging science to produce better violins is not necessarily easy.

Even your questions are not defined in measurable terms, 'brighter', 'bounce capacity'

You can scour literature on material science. Even if you could find something relevant from the perspective of the topic, I am not sure it could even be applied.

What it is that you want? Do you want to be able to select better bows? Do you want to find a material that is an alternative to pernambuco?

December 14, 2022, 6:51 AM · I think it is very much an evolutionary thing: pernambuco just works very well for bows. by the way at some point even steel bows were in fashion, and Paganini endorsed them strongly, although there is no historical proof that he actually used them in performance.

December 14, 2022, 7:17 AM · Like many violinists I have two bows. One is the bow that came with the violin package deal that my wife's great grandfather purchased in Europe before he emigrated to the USA. I'm still trying to discern its provenance. The other (Adolph C. Schuster***) I purchased at the time I bought a violin to upgrade and later sold.

The Schuster is demonstrably louder than the other bow. The differences: Round vs. Octagonal and the Schuster is about 10 grams heavier. Both are good bows with very little lateral flex. Neither have been re-cambered.

I've asked others to play with both bows and the Schuster is always louder for all players.

Maybe in the end it's like Harry Potter and the bow chooses the violinist. Simply magic.

Maybe there is a bowmaker on the forum that can explain the properties of bows.

December 14, 2022, 7:17 AM · Like many violinists I have two bows. One is the bow that came with the violin package deal that my wife's great grandfather purchased in Europe before he emigrated to the USA. I'm still trying to discern its provenance. The other (Adolph C. Schuster***) I purchased at the time I bought a violin to upgrade and later sold.

The Schuster is demonstrably louder than the other bow. The differences: Round vs. Octagonal and the Schuster is about 10 grams heavier. Both are good bows with very little lateral flex. Neither have been re-cambered.

I've asked others to play with both bows and the Schuster is always louder for all players.

Maybe in the end it's like Harry Potter and the bow chooses the violinist. Simply magic.

Maybe there is a bowmaker on the forum that can explain the properties of bows.

Edited: December 15, 2022, 7:59 AM · There is great variation in the physical properties of pernambuco wood in relation to quality for bow making.

Next year (a couple of weeks from today) will mark the 40th anniversary of Giovanni Lucchi's invention of the "Lucchimeter," an instrument advertised to measure the properties of wood related to its quality for bow making.

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

The advertisements are not sufficient to prove anything, but some people see value in the relationship to potential bow quality.

I have not done any significant research on bow properties related to vibrations and the velocity of sound in pernambuco sticks, but I hypothesize that bow behaviors related to sound production are related to the vibration of the hair in contact with the string due to the acoustic resistance (acceptance) at the hair-stick interface and damping by the stick. (In other words any vibration of the hair will interfere with the straightforward "stick-slip" coupling of hair and string.)

In agreement with George's observations of the loudness of sound produced by his bows, I have found the same thing with my bows - and it is not related to the weight of the sticks, that I have all measured (in fact I have written them on the white and silver tips). But there is much more to it than that.

Then too, there are the obviously dynamic properties of bows - how well do they bounce. I have found some bows they seemed able to read my mind and bounce just the way I wanted with the sense that I just had to think it. Unfortunately I have never owned a bow that perceptive.

Rosin choice can make a big difference in the sound produced by any bow.

Late in the 1990s I visited retired violin maker/luthier/dealer Frank Passa at his home in Santa Rosa, CA (this was after his stroke and not long before his death). In the 5-car garage under his house were largestacks of pernambuco blanks, precut for their ultimate use as (violin, viola, cello and bass) bow sticks. It was impressive!

A few years later I was chatting with Jay Ifshin at his Berkeley "Ifshin Violins" shop and I mentioned that wood in relation to Morgan Anderson (a bow maker associate of Jay's who had studied at the Violin School of America as a classmate of Jay's). Jay told me that that wood was not good enough for Anderson's bows (which at the time were selling for about $3,200, but of 11 bows [by now) sold at auction, Anderson's record price was $7,200 for a violin bow. I did get to try a couple of Anderson's bows back in those days and they were very fine in sound and every other characteristic you could want.

December 14, 2022, 10:03 AM · Here is one lecture/demo: https://www.youtube.com/watch?v=aEuo6-xzyDI

Edited: December 15, 2022, 1:39 AM · My bow is made from unicorn horn and tail hair, so I can't help.

Edited: December 15, 2022, 2:14 PM · If I suspend my bows from either end and gently tap the stick, they sound with different pitches. The pitch doesn't seem to depend on how much the bow is tightened, so it must be a property of the stick itself....

December 16, 2022, 3:52 PM · If you tap in small increments in a straight line along the top of the bow stick (0 degrees) in one direction (from the tip) you will hear four pitch points separated by musical 5ths E-A-D-G then G-D-A-E…..repeating. I call this a “pitch sense”. At 45 degrees you will hear the same sequence reversed. This continues every 45 degrees (like an octagon) around the circumference of the bow stick. Think about representing it as a line with an arrowhead —-> == G-D-A-E. On “so-so” bows, these pitch senses are not aligned circumferentially around the stick. The bow will typically have dynamics issues and the tone drawn from the violin will not be very satisfying. On “good” bows these pitch senses are aligned circumferentially and reverse direction every 45 degrees around the circumference. Depending on the degree of alignment, the bow dynamics are excellent and the tone drawn from the violin is very satisfying. You can demonstrate this for yourself by drawing accurately (say with a china marker) two single-line circles perpendicularly around the circumference on the surface of the bow stick, one near the tip and the other near the winding at the frog end. This aligns the pitch senses circumferentially.

The pitch senses are not a property of the bow stick. They are present on bows of any material (Pernambuco, fiberglass, carbon fiber, etc.) and size. The pitch senses are a manifestation of a three-dimensional field (fields) in the air surrounding the bow stick and originating on the bow stick. (Think of the electric and magnetic fields associated with an electrical wire carrying a current.) They are configured (shaped) according to the shape of the bow surface but can also, fortunately, be reconfigured easily by drawing lines (discontinuities) on the bow stick. There appear to be three interconnected orthogonal fields: axial (along the direction of the stick) radial (outward from the stick) and circumferential (around the circumference of the stick). To confirm this, these fields can be mapped. Lay the bow on a flat surface and tap in the area around the bow stick. You will detect the same pitch senses on the flat surface (radial and axial pitch senses). At different 45-degree angles around the bow stick, the pattern changes. (You need to have a surface along the centerline of the bow for an accurate picture of the orthogonal pitch senses). Using a flat thin plate (I use acrylic plastic say .25 x 3x3 inches (3 x 150 x 150 mm) held in the fingers, the plate becomes a “pitch sense probe”. By manipulating and tapping on the acrylic plate surface with the china marker you can detect the direction of the pitch senses as they pass through the plate perpendicularly or are aligned with the surface of the probe. With the acrylic probe, you can detect all three types of pitch sense field around the bow stick.

December 17, 2022, 11:35 AM · Ted Sinoski, Gordan Shumway's suggestion that his bow is made from unicorn horn and tail hair comes across as being more credible than your theory.

I don't know of any highly successful bowmaker who does what you have suggested, and I do know a bunch of 'em.

December 17, 2022, 4:21 PM · Oh dear, I am now watching videos of solitons instead of practicing!

December 17, 2022, 6:26 PM · Gordon better be careful with that at US Customs.

December 17, 2022, 8:23 PM · So the only thing that matters is the geometry of the bow, which defines the air field around it? Alright, well, I'll make a bow out of modelling clay with the precise weight and dimensions of my pernambuco master bow, and they should play the same!

Edited: December 18, 2022, 3:14 AM · Serious question - why are some bow sticks octagonal? I can't possibly believe this mumbo-jumbo:

https://violinlounge.com/product-review/round-vs-octagonal-arcus-violin-bow-review-violin-lounge-tv-409/#:~:text=Traditionally%20bows%20come%20in%20two,a%20bit%20stiffer%20and%20lively.

so maybe the sound becomes more satisfying when the faces are in alignment with the sense fields..?

December 18, 2022, 9:28 AM · Gordon, don't let the secret out, or we will soon see loads of white bows with pink strings

Edited: December 18, 2022, 10:13 AM · Steve, what? You can't possibly have encountered mumbo-jumbo on a violin blog. "Pros know!"

December 18, 2022, 12:57 PM · Still, David and Ted, I'd love to see a video illustrating this gathering of data. Just in case we all need something to keep us awake on a cold afternoon.

Edited: December 19, 2022, 4:35 AM · Steve Jones, all traditionally-made wooden bows start out octagonal. This is because the traditional hand-worked method of making a round cross section, or a dowel, is to first plane it square. Then you plane off the four corners, resulting in an octagon. If one wants to continue on toward round, you plane off the remaining corners again, and so on. Final rounding of any remaining faceting may be done with a file, or with abrasives.

A maker may decide to continue on from octagonal to round because their personal style, or the style of bow they are imitating is round; or because that is what the client wants; or because they want to remove a little more weight or stiffness from the bow.

This web page, from the Jerry Pasewicz shop, includes photos taking you through the various steps. In this case, they are making a soundpost rather than a bow, but the process is very similar.

https://trianglestrings.com/soundpost/

December 19, 2022, 5:45 AM · Thanks David. I mistakenly assumed it was the octagonal pattern that involved an extra stage of whittling. Now it makes more sense that the only octagonal ones hanging over my desk are Chinese give-aways.

December 19, 2022, 7:27 AM · This where I get sneered at for suggesting that to compare two bows they should have hair from the same horse. And the same amount of the same rosin.

December 19, 2022, 7:45 AM · Just as comparing two cars requires fitting them with the same size and brand of tires.

Edited: December 19, 2022, 9:12 AM · Steve, on cheap bows, a round one may be mostly turned on a lathe, or an octagonal one may have the facets cut on a CNC or a milling machine. Last time I visited a violin factory in China though, many things were still done by hand, since the cost of labor for doing some things could still be cheaper than investing in expensive machines.

It's possible that much more was done by machine than I realized though, since I was only shown small parts of the factory.

Edited: December 19, 2022, 9:15 AM · Steve, yes, if the two cars use the same sized wheels!
No, if we compare a violin bow to a cello bow...

We see as many discussions on rosin as on the cross-section of bow sticks, and it's the bow hair that holds the rosin sufficiently in line for us to use it.

December 19, 2022, 11:35 AM · Gordon, I thought your Unicorn bow was sheer fantasy, but I just read an article in the January 2023 issue of The STRAD magazine about a Russian baroque bow made of IVORY. I quote the first 2 paragraphs of the article below:

"L’ Archet, the seminal two-volume work on bow makers by Bernard Millant and Jean-Francois Raffin, contains many examples of bows from down the ages. A most intriguing example, which appears on pages 186–7 of the first volume, is an ivory bow commissioned personally by the Russian empress Catherine the Great. Made entirely from mammoth tusk, the stick has a swan-bill head while the frog is made from a single piece of nacre (mother-of-pearl), decorated on each side with four small diamonds. The audience side features the inscription Catarina II Russiarum Imperatrix Fecit . et dedit A. Lolli. 1776 (‘Catherine II, Empress of Russia: made [for] and given [to] A. Lolli [in] 1776’). The bow has retained its original case, apparently crafted by the same maker as the bow.

The brief description by Bernard Gaudfroy in L’ Archet treats the bow as a historical artefact from the collection of Claude Lebet, but includes no attempt at attribution. Nor has any other account of the bow in the past 200 years made any suggestion as to who might have made it. Until now, the first Russian bow maker whose name we know is Nikolai Kittel (1806–68), whose earliest examples date from the 1830s; to ascribe this artefact to a professional bow maker rather than an artisan would effectively rewrite the history of bow making in Russia by a full 60 years. However, the Lolli bow was indeed carved by a bow maker, who was also the leading ivory craftsman of his time: Osip Kristoforovich Dudin (c.1714 –85). A contemporary of Nicolas Pierre Tourte (1700–64), Dudin appears to have been the only craftsman engaged in such work in St Petersburg in the 1770s. The importance of Catherine the Great’s commission confirms Dudin’s standing as the most respected ivory carver and bow maker of his day in Russia."

So "your bow" is probably only half-fantasy (the unicorn half).

Edited: December 19, 2022, 11:56 AM · Adrian,

If you are tracking single variables (color of wood, say), then there is some value to keeping the hair identical.

Unfortunately, most bows have many more than one variable at play, because it is nearly impossible to make copies. In that case, the useful thing for most shoppers (not researchers) is to have each sample sound its best, whatever that means.

Stephen

January 1, 2023, 1:58 AM · I recall visiting Frank Passa's shop back in the mid '90s. His bows were distinct and he was selling them for around $5000. Based on what I know now I think they were high quality in terms of sound and playability. He showed me his extensive inventory of pernambuco. He had apprentices learning from him. I think that his greatest contribution was the threaded 'sacconi' tailgut.

Edited: January 1, 2023, 3:01 PM · I'm not sure if his apprentices were learning from Passa, or if he was learning from them. The "Passa" bows were made by an extremely talented guy named Reid Kowalis. I think Morgan Anderson was working there for a while too.