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refractive ground question


MikeC

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Or, suppose they did use common materials and techniques, and it takes ~200 years to develop its beneficial higher damping properties? Also seems rather unlikely to me.

I recall reading that Amati's and Stainer's instruments were more highly revered in Strad's time among the musicians. It wasn't until later that Strad's instruments were more in vogue.

Could it be that they hadn't yet matured in tone to be favorable with the contemporary musicians of Strad's time?

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Or something else I haven't though of.

Could be... Maybe even something I haven't thought of. :)

Not to throw a wrench into the logic (much of which I agree with), but I did mention that a few more modern instruments seemed to have similar properties... and some older instruments did not. I mentioned bullet-proof varnish on the bell like older ones... but I may have neglected to mention that one or two (not all) of the more modern ones I mentioned were copies... and I had the distinct impression the wood may have been "treated". With what, I don't know. I think it's important to factor in that these days I work on (open) more older instruments than newer ones... Also, I do think small things tend to add up... and I'm pointing to what I see as a trend, not a gospel.

In addition, I wanted to restate my initial observation... that "I don't find that many fine old instruments that I've had apart have tops that "ring like a bell". Some ring a bit more than others, but there's a distinct "thuddy" factor present. Constantly makes me consider the ringing/damping relationship when working on them."

So... At least when replying to my posts, I appreciate it if we could avoid swinging into the idea of "higher" or imply "excessive" damping... go there on your own if you want to... but I feel it's like saying that if it's not white, it's black. If "they" didn't use cement, it must be goop. Not what I've said or implied and I've clearly stated that I haven't presented a rating "scale" or frequency range and don't intend to.

Yes, this topic has been discussed preiously, with no conclusion that I can recall. There was even disagreement as to whether the thud effect was even real.

Two things.

1) Again, I'm simply stating an observation. I've urged others to check things out for themselves and draw their own conclusions.

2) Disagreement by and between whom (I'd say that might be a rather important factor)? I don't believe I'm delusional (but then again, how would I really know if I am? :)).

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The first house I bought was made in 1885. I had to remove some damaged pine baseboard and replace it with new wood.

I was quite surprised at how different the old wood was compared to "new." It felt much softer to the gouge, almost like "punky" new wood, but it wasn't from environmental damage... the stuff had been completely dry for the entire time and had been sawn from healthy timber. The best analogy I can give is that it felt like balsa under the blade... Definitely different. Also a beautiful brown patina that penetrated quite deeply into the surface.

E

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The first house I bought was made in 1885. I had to remove some damaged pine baseboard and replace it with new wood.

I was quite surprised at how different the old wood was compared to "new." It felt much softer to the gouge, almost like "punky" new wood, but it wasn't from environmental damage... the stuff had been completely dry for the entire time and had been sawn from healthy timber. The best analogy I can give is that it felt like balsa under the blade... Definitely different. Also a beautiful brown patina that penetrated quite deeply into the surface.

E

'pumpkin wood'

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Applying some logic here, does it seem reasonable that makers over a few hundred year span were doing something in the ground/varnish that is not in use today, and that "something" makes a significant difference in plate taptone and complete instrument sound? That seems highly unlikely to me.

Or, suppose they did use common materials and techniques, and it takes ~200 years to develop its beneficial higher damping properties? Also seems rather unlikely to me.

From the other thread on linseed ground, and my limited experience, the ground and varnish, applied thinly, have a minimal effect on the sound (not zero, but definitely not the difference between great and average instruments). If something is done to increase the damping (as in too much goo), the sound goes dead. In my opinion, higher damping is not a good thing.

From the above reasoning, I find it hard to imagine that the ground/varnish, or even damping alone, are at work here. There must be something else.

The "something elses" that I can imagine are:

1) Some complex interaction of wood properties and free-plate mode shapes, with the properties of the wood changing slowly with age.

2) Edge damage, or crossgrain microcracking... the free-plate modes involve some amount of edge bending and stretching which is not so important in the assembled instrument. Perhaps accumulated edge degradation (possibly even invisible) could cause the taptones to thud.

Or something else I haven't though of. Yes, this topic has been discussed preiously, with no conclusion that I can recall. There was even disagreement as to whether the thud effect was even real.

Don,

On the thoughts about ground + aging + what is going on...Here is an article by Terry Borman. His research and that of John Waddle are interesting and I keep returning to the Borman observations. Simply put he sees a similarity of density cross grain in old instruments that is not explained by simple aging. It bears consideration when we think about ground materials and methods.

Joe

PLosOne_Comparison_Cremonese_Modern.pdf

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scodatura,

If you click on the varnish system link below you will get an overview. My convictions....interesting wording....include the input I have had from makers, the scientific analysis, historical and technical writings and my own experience as a varnisher. Most important to me, though, is seeing a detail and then learning to reproduce it...preferably using the resources that were available to the classic period makers. I have a strong interest in the nature and appearance of the original varnish as it came from the hand of the maker.

Joe

Joe

I would not read into my use of the word convictions. It just seemed that you were convinced that linseed was the first application to the wood. I have considered purchasing your varnish system. I am just trying to understand what it is and why you are doing it that way. For me sound and appearance are equally important. Not saying that you are not approaching it that way but I get the impression that for some it is about how it looks. As a player who makes, I would sacrifice sound over looks. But only a tiny bit!

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Violin Varnish Ltd. Varnish System Overview

"The Balsam Ground System reproduces all of these qualities."

LM,

No. Sorry if I was not clear on this: I do not think that linseed oil was used as an intention ground material on the classic Italian instruments. But I think it best to keep an open mind...so until this notion of linseed oil on the wood debunked I leave open the chance for me to be wrong. Too many "authorities" have given us ultimate answers over the years for me to be absolute. What I can tell you about the ground method that I use is that I can reproduce the physical and optical effects of the Italian ground in a way that does not hurt the instruments....well, at least no-one has complained yet! The appearance 300 years from now is something I will have to wait for. Whether this method is historically authentic is still a matter of debate. My focus is to provide and use the tools that work for me.

on we go,

Joe

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On the slightly off-topic issue...

Jeffrey,

I do not question your observations, only trying to recall what went before (vaguely). I only bring up extremes as thought examples, with no bearing on your statements. However, it does seem to me that damping can be varied to some degree in new instruments with coatings, and as far as I know there has been no benefits... thus my opinion that the (presumed) high damping of thuddy old plates is not the real source of good sound.

By the way... have you ever hacked into those cooked wood samples I sent? I can send some more, if they disappeared.

Joe,

Yes, I recall this Borman article from a while back. I don't know enough about the wood structure and chemistry to say if aging causes the more uniform density, or if the old Cremonese wood started out that way. Or if there is some technicality in the measurement that produces this apparent result (the density differential isn't measured directly, but inferred in some complex way).

With the thuddiness and density differential, there is no clear path from these observation to improved acoustics that I can see yet. They may indeed be important in some way, or a side effect that develops along with some property that is truly important acoustically, or even none of the above. The answer might be about as simple as the Unified Field Theory.

Back to the thread's topic:

I removed the varnish (and as much ground as possible) from my latest fiddle, as it didn't look as good as I thought it could. I think it looks a LOT better now, with much more lively figure. I can't say how much improvement is due to the ground (copal/turpentine vs. glue and shellac), and how much is due to the colored varnish... but I'd guess some of each. I'll post the photos in my fiddle thread here.

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Those of you who have seen them in person. Is there the same reflective and refractive quality on the top as on the back?

Hi Mike,

Although J.B. Guadagnini is not exactly classic Cremonese varnish, here is a shot of the table of a violin from circa 1776 made in Turin. You can see the dirt under the tailpiece area, the color layer and lower layer with little color and finally the darkened wood once the spruce comes into contact with perspiration, dirt, oil and the like.

This also makes me think that the wood has not been darkened excessively before varnishing. The varnish also has a certain thickness which shows a relatively wide step from one layer to the next (Edit: The color layer is thinner than the underlying layer). If it were an excessively thin color coat the the step would be more abrupt like we see on some of the French instruments from the Bernardels for example.

Bruce

post-29446-0-46423700-1300128485_thumb.jpg

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Hi Mike,

Although J.B. Guadagnini is not exactly classic Cremonese varnish, here is a shot of the table of a violin from circa 1776 made in Turin. You can see the dirt under the tailpiece area, the color layer and lower layer with little color and finally the darkened wood once the spruce comes into contact with perspiration, dirt, oil and the like.

This also makes me think that the wood has not been darkened excessively befor varnishing. The varnish also has a certain thickness which shows a relatively wide step from one layer to the next. If it were an excessively thin color coat the the step would be more abrupt like we see on some of the French instruments from the Bernardels for example.

Bruce

Thanks for the picture Bruce. There are a couple interesting things that stand out, unless I'm just imagining things. First I would say the color is fairly accurate considering the inner layer of the purfling looks whitish compared to the ground layer on the wood which looks yellow (gold). Also I put a black circle around a spot that looks like a small scratch of flake of the ground revealing white wood underneath, recent because it hasn't turned dark brown due to age and grime and etc. That scratch (if that's what it is) is confined by two dark growth lines which is what you would expect from a small scratch since that part of the wood is higher than the dark lines (corduroy) That also gives some idea of the thickness of the ground layer.

post-31367-0-81220900-1300131397_thumb.jpg

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Thanks for the picture Bruce. There are a couple interesting things that stand out, unless I'm just imagining things. First I would say the color is fairly accurate considering the inner layer of the purfling looks whitish compared to the ground layer on the wood which looks yellow (gold). Also I put a black circle around a spot that looks like a small scratch of flake of the ground revealing white wood underneath, recent because it hasn't turned dark brown due to age and grime and etc. That scratch (if that's what it is) is confined by two dark growth lines which is what you would expect from a small scratch since that part of the wood is higher than the dark lines (corduroy) That also gives some idea of the thickness of the ground layer.

The photograph might still be a little too yellow but the varnish color, even in daylight, does not have much red in it.

Purfling on J.B. Guadagnini isn't as light a color as some of the Cremonese, he most often used a light shade of walnut wood (two dyed black).

Bruce

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so the varnish is more brownish? What do you think of the spot I circled. Is that a missing bit of ground exposing wood underneath?

It's a scratch and some wood is missing too (your scratch can be found in the upper right hand corner of the first photograph). See below. That's as close as I can get without a microscope. I like my little camera. :D

The varnish color could be called a brownish golden orange.

Bruce

post-29446-0-35060800-1300133038_thumb.jpg post-29446-0-54485900-1300133050_thumb.jpg

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Nice closeups and nice camera! Would you say that this has the same properties as the cremona finish? highly reflective and refractive? The spot of exposed wood itself seems to have some shiny reflectiveness.

It has a satin-like sheen to it when turned in the light which is very attractive and perhaps mostly due to the rather thicker layer under the color layer. If you take the best Cremonese and the best Guadagnini I would still prefer the Cremonese but J.B.G. at times had a very fine varnish.

(Edit: the scratch has a veil of transparent varnish over it.)

Bruce

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From the above reasoning, I find it hard to imagine that the ground/varnish, or even damping alone, are at work here. There must be something else.

The "something elses" that I can imagine are:

1) Some complex interaction of wood properties and free-plate mode shapes, with the properties of the wood changing slowly with age.

2) Edge damage, or crossgrain microcracking... the free-plate modes involve some amount of edge bending and stretching which is not so important in the assembled instrument. Perhaps accumulated edge degradation (possibly even invisible) could cause the taptones to thud.

Or something else I haven't though of.

An important something else is the oxidation on the Hemicellulose in the wood.

It is claimed that the oxidation of Hemicellulose is the cause of the opacification

of wood with time. The Hemicellulose goes away and leaves voids in the wood.

This makes scattering points in the wood, making it opaque.

And making the wood lighter and more damping. This flattens the high resonance peaks

so the instrument is more even in its response.

This all happens slowly. And is not controlled by any man.

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It's a scratch and some wood is missing too (your scratch can be found in the upper right hand corner of the first photograph). See below. That's as close as I can get without a microscope. I like my little camera. :D

The varnish color could be called a brownish golden orange.

Bruce

post-29446-0-35060800-1300133038_thumb.jpg post-29446-0-54485900-1300133050_thumb.jpg

Bruce,

Nice scratch. As we look at this exposed wood it appears as quite white [part of that being the white reflection off the surface varnish]. This is a factor in how we see ground in photographs as opposed to real life.

My guess is that this white surface, viewed at an oblique angle, would appear the color of cardboard.

We certainly have seen some fine examples of the ground in the Guadagninni instruments...how does the maple look in this one?

Attached is one of a 1784 Guisseppe Guadagninni with brown/gold varnish over a tasty ground.

on we go,

Joe

post-6284-0-62287500-1300234521_thumb.jpg

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My guess is that this white surface, viewed at an oblique angle, would appear the color of cardboard.

The exposed ground on this one (late J. B. Guad) is pretty "white" even when viewed at oblique angles.

post-17-0-97451100-1300237246_thumb.jpg

(sorry for the larger file... figured Joe would appreciate being able to put his nose right in it! :))

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Having fun reading the thread, folks... and I'm going to steer clear of the linseed thing... but just wanted to mention that I don't find that many fine old instruments that I've had apart have tops that "ring like a bell". Some ring a bit more than others, but there's a distinct "thuddy" factor present. Constantly makes me consider the ringing/damping relationship when working on them.

I've found that when carving a violin plate it can ring like a bell when it is a little on the thick side. There seems to be a hard to identify line that onced crossed results in a reduction of the ringy-ness which is then replaced with a thuddy-ness. I don't know the exact reason why this quality comes out. Have the more thuddy tops that you've seen been a little thin?

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