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Stradivari's golden ground varnish


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2 hours ago, Don Noon said:

I oversimplified my explanation, so let me try an easier to understand analogy.

Wood is a bundle of linear cells, and the reflection comes from the large refraction index difference between the cell wall and the air inside the cell (assuming the wood has been varnished, thereby eliminating the reflection from the outside surface of the cells).  The internal reflecting surface is not flat like a mirror, but more like a bundle of hair... linear, but round... so along the grain it is more specular, but perpendicular to the grain it is more scattered.

Figured wood is more like curly hair, with more complex reflection and scattering going on.  And taking the analogy one step farther, the contrast is most apparent with dark hair (and dark wood).

042919-hair-texture-embed.jpg

yes

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31 minutes ago, joerobson said:

I think your observation is correct from a static point of view...as in the hair photo or a poster of an instrument.   In real life and varying lights we are looking at light in motion.  Especially when observing the spruce.

I agree with that too , but to me this is where things start getting "quantum" in that I feel that, there is the "realness" of actual motion and or the observers vantage point of observation "moves" as well as the source angle of the light, an actual "real" motion, but then we have the much more strange quantum effect related to a "Neckler cube" and how a 3-d object represented on a 2d plane has the ability to "flip" its state thus showing in a way a certain type of "motion" that in actuality is simply demonstrating quantum entanglement. Making us "think" we saw a change or motion, and we did, but nothing moved, it literally happens faster than the speed of light, but only because no information was transferred. so in both Maple and Spruce we "see" holographic" effects in the wood that give 3 dimensional "pictures" and or areas when we observe them , a certain visual "illusion" of 3d being demonstrated on basically the 2d surface of the wood, and that can, like a neckler cube force us to visualize 3d shapes/quadrants on the wood surface and have the ability to "flip" like a cube, making us "think" we saw motion, when really it was just entangled photons changing their state. :lol:

 

 

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3 hours ago, Don Noon said:

Figured wood is more like curly hair, with more complex reflection and scattering going on.  And taking the analogy one step farther, the contrast is most apparent with dark hair (and dark wood).

042919-hair-texture-embed.jpg

Agreed. Nice example. The light and dark areas of the hair will change with both the viewing angle and the angle of the light, while the color of the hair itself remains the same.

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5 hours ago, joerobson said:

Light enters the wood about 7 microns.  It is the scattering of the light within the wood and the multi faceted internal reflectivity of the wood that gives the "inner fire" that is remarkable about this ground.

Light enters far further than 7 microns.  Based on my own observations I suspect up to 6 cell layers deep.  Each cell is approximately 30 microns wide so that's quite some distance.

I agree with your second sentence quoted above.  Interestingly it seems that it is the components of wood cell structure aligned towards or at right angles to incident light that reflect light.  I can possibly post photos to illustrate this if you are interested.

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3 minutes ago, John Harte said:

Light enters far further than 7 microns.  Based on my own observations I suspect up to 6 cell layers deep.  Each cell is approximately 30 microns wide so that's quite some distance.

I agree with your second sentence quoted above.  Interestingly it seems that it is the components of wood cell structure aligned towards or at right angles to incident light that reflect light.  I can possibly post photos to illustrate this if you are interested.

John,

Your pictures are always welcome.

Joe

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1 hour ago, joerobson said:

John,

Your pictures are always welcome.

Joe

Joe (and Mike) I was hoping you wouldn't see my post...:D

Five reduced size photos are posted below.  Each is labelled, indicating instruments involved and the direction of the point source incident light.  The first four photos feature spruce while the fifth, maple.  Maple is a more complex situation due to the undulating nature of the fiber direction.

Of note in the first two photos is incident light focused along the grain resulting in the medullary rays/plates at right angles to the incident light strongly reflecting light.  In a relative sense, most of the other wood cell structural detail seems absent. 

In contrast to this, the next two photos illustrate the effect of light focused across the grain.  Here the along grain structural detail reflects light while the medullary darken/appear absent.

If spruce viewed under a point light source is rolled relative to the light source, it is possible to see the various medullary effects at different levels move relative to one another, creating a sense depth.  In maple, not only do the medullary appear to move relative to one another, but the undulating fiber direction and how it reflects light or not creates the light and dark areas that we see as flaming.  The final photo below featuring a section of maple hopefully suggests this.

I hope that this all makes sense and does illustrate that it is components of wood cell structure aligned towards or at right angles to incident light that reflect light.

I may be able to find some photos to illustrate the extent to which light can penetrate wood structure, but that will take a little longer than this.

N Amati spruce - light along grain.JPG

N Amati 1655 spruce - light along grain_cropped.JPG

N Amati spruce  - light across grain.JPG

N Amati 1655 spruce  - light across grain_cropped.JPG

Strad 1703 maple - light along grain.jpg

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Spruce and maple differ in that the cell structure of spruce is much larger (except for the vessels in maple), and the rays are in thin, flat-ish strips.  The spruce cells are also more regularly rectangular, perhaps giving flat reflecting surfaces as well as better visibility into deeper layers.

I have some microscope photos of spruce with just plain clear varnish on it, highlighting the rays and longitudinal grain respectively.  We are all talking about the reflectivity of the wood itself... which has nothing at all directly to do with ground or varnish.  For maximum "sparkle" (i.e. reflections), you need a coating to fill up the chaotic torn up first cell layer and provide a smooth window into the wood.  That's it.  Anything else... stain, colored varnish, whatever, will give a stained glass window and diminish what comes from the wood reflections. 

But maximum reflection might have to be traded off for color, assuming you want some.  Stain or varnish won't penetrate perpendicularly into spruce; it will remain on the surface.  So if the cell walls themselves have any color, it will have a gradual attenuation of the deeper layers, as opposed to a uniform attenuation of everything when color is applied on the surface.  Then things get more complicated with endgrain issues for figured maple.

435615687_nearleft.jpg.b1c6fbe0ede371a570de77e540d90574.jpg473890504_nearbottom.jpg.0407b8a3297233ca3f79e067663e18ac.jpg

Edit:  the blue-ish glints are due to using an LED light source that is very blue.

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2 hours ago, Michael_Molnar said:

In a nutshell, I think John’s photos show stained wood. A stain infuses the wood structure enhancing its visibility. A layer of colored varnish alone cannot recreate this.

Yes some form of stain could well be involved.  At least some wetting of the wood structure with varnish or similar seems important in achieving the type of look seen in my photos.  Other factors like wood ageing etc., etc., also seem to make a difference. 

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2 hours ago, Don Noon said:

Spruce and maple differ in that the cell structure of spruce is much larger (except for the vessels in maple), and the rays are in thin, flat-ish strips. 

Maple may be more open celled than you imagine.  Maple tracheids are not a lot smaller than spruce tracheids.  See lower photo in first image below.  As you note, maple vessels/pores are much larger again, around 100 microns wide.

The spruce cells are also more regularly rectangular, perhaps giving flat reflecting surfaces as well as better visibility into deeper layers.

The second image below is the quartered face of some European spruce.  No varnish, treatment or otherwise involved.  The surfaces are reflective but I am not sure that this is due to flatness.

I would have thought that good visibility into deeper layers of maple would be at least the equal of that into spruce. 

I have some microscope photos of spruce with just plain clear varnish on it, highlighting the rays and longitudinal grain respectively.  We are all talking about the reflectivity of the wood itself... which has nothing at all directly to do with ground or varnish.  For maximum "sparkle" (i.e. reflections), you need a coating to fill up the chaotic torn up first cell layer and provide a smooth window into the wood.  That's it.  Anything else... stain, colored varnish, whatever, will give a stained glass window and diminish what comes from the wood reflections. 

But maximum reflection might have to be traded off for color, assuming you want some.  Stain or varnish won't penetrate perpendicularly into spruce; it will remain on the surface. 

I'm not so sure about this.  Microsample material, various photos taken under magnification and material seen in the base of belly soundpost patch beds may suggest otherwise. 

So if the cell walls themselves have any color, it will have a gradual attenuation of the deeper layers, as opposed to a uniform attenuation of everything when color is applied on the surface.  Then things get more complicated with endgrain issues for figured maple.

I agree that this is often the case with stains.  However there are forms of colouration where this seems less of an issue.

 

Maple detail.jpg

Bachmann 2013.jpg

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15 hours ago, MikeC said:

I'll have to dig up my old textbook on quantum mechanics to figure out what Jezzupe is talking about  :D  

Well it's actually a whole bunch of things in one, mostly related to holographic or visual perception illusions related to cognitive perception, which along with several other converging ideas are giving way to the fast gaining acceptance field of quantum consciousness as a fundamental and the death of space time. 

Or simply instead of consciousness being a by product of space/time it is space time that is a by product or manifestation of consciousness. Several theories, experiments, facts are converging giving strong evidence that we are in fact inside of some type of simulated reality and our world as we know it is in fact a holographic illusion. Donald Hoffman from Irvine and Chetan Prakash have some amazing work in this field.

And in all that our visual perceptions leave many clues, mainly understanding how our vision renders our reality and is not acting like a camera. Our minds are constantly filling in the blanks because they are generating what we see, not the other way around, and optical illusions are a good way to tie it together.

So in our case, in wood, these optical illusions often times are demonstrating and or giving visual examples of superposition and or entanglement , an example is we see pareidolias in the grain where "faces, animals, objects" appear visually, but then we look away and they are gone, and then by staring at it enough we get them to come back.

Some examples of these illusion are the Neckler cube, or types of pictures/art where when we first observe the picture we clearly see the face of a lady, but then all of sudden the face turns into mans face, and then after a bit they will flip visually between the two, this is a similar visual experience as the flipping states of perspective of a Neckler cube. We could even think of flamed Maple as being in several states depending on angle, lighting and vantage point, inducing a "feeling" of motion, we know the flame did not change location, its just the new angle and lighting interaction with the grain makes us see a different grain pattern, making it appear that it "moved" 

We do the same thing with lighting and shade related to color, we are constantly filling in the blanks and many times what we see color wise is not accurate and it is our minds that are filling in the blanks. The same exact color may appear to be two separate colors if two separate objects are viewed at the same time when one of those objects is cast in different lighting, our brains generate different colors because our brains have been tricked by the shade. Again all of this steers us towards the uncomfortable reality that our eyes are not acting like a camera that is soaking in what it see's as much as our eyes are creating what we see and that "We all" are experiencing the same reality based on the fact that we are the same species interacting with the same interface while being entangled conscious agents in the same construct.

So the long and the short of it is my response to Joe was simply saying that wood grain has the ability to generate optical illusions that can distort our perceptions of what it is we see.

If you are into further understanding this may help.

 

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The whole reflectivity thing is a double edged sword. Nothing sparkles or displays depth like freshly planed wood with a clear varnish applied over it, but with maple and spruce this doesn't offer much color or contrast with the wood grain. If you apply a stain, it soaks into the upper cells it adds more color and contrast, yet diminishes the reflectivity of the surface. A very light staining may be the answer, but it's certainly a balancing act.

I have a violin that;s been sitting for 6 or 7 years without varnish, although I tanned it under UV, and applied a thin wash of turpentine spirits with a few drops of linseed oil over the entire instrument. It has darkened in a pleasing manner, but who wants to wait years for this change to take place.

One thing I have noticed while in the attic of my wood shop, the spruce trusses have turned a beautiful dark golden yellow color, and where there is runout or waves in the grain, a very reflective, striking chatoyancy is displayed. This was all achieved without any sunlight exposure, only dry heat in the summers.

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The whole reflectivity thing is a double edged sword. Nothing sparkles like freshly planed wood with a clear varnish applied over it, but with maple and spruce this doesn't offer much color or contrast with the wood grain. If you apply a stain, it soaks into the upper cells it adds more color and contrast, yet diminishes the reflectivity of the surface. A very light staining may be the answer, but it's certainly a balancing act.

I have a violin that;s been sitting for 6 or 7 years without varnish, although I tanned it under UV, and applied a thin wash of turpentine spirits with a few drops of linseed oil over the entire instrument. It has darkened in a pleasing manner, but who wants to wait years for this change to take place.

One thing I have noticed while in the attic of my wood shop, the spruce trusses have turned a beautiful dark golden yellow color, and where there is runout or waves in the grain, a very reflective, striking chatoyancy is displayed. This was all achieved without any sunlight exposure, only dry heat in the summers.

 

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21 minutes ago, Bill Yacey said:

The whole reflectivity thing is a double edged sword. Nothing sparkles or displays depth like freshly planed wood with a clear varnish applied over it, but with maple and spruce this doesn't offer much color or contrast with the wood grain. If you apply a stain, it soaks into the upper cells it adds more color and contrast, yet diminishes the reflectivity of the surface. A very light staining may be the answer, but it's certainly a balancing act.

I have a violin that;s been sitting for 6 or 7 years without varnish, although I tanned it under UV, and applied a thin wash of turpentine spirits with a few drops of linseed oil over the entire instrument. It has darkened in a pleasing manner, but who wants to wait years for this change to take place.

One thing I have noticed while in the attic of my wood shop, the spruce trusses have turned a beautiful dark golden yellow color, and where there is runout or waves in the grain, a very reflective, striking chatoyancy is displayed. This was all achieved without any sunlight exposure, only dry heat in the summers.

Yes well there is oxidation of the surface as well as precipitation crystallization of the distributed saps/sugars and cellulose in the surface grain, particularly in the softwood, all can contribute to color change over time.

This "thing" poses one of the biggest problems in home remodel and repair, and I suppose with violin repair as well and that is color matching and or blending in repair work on pre existing older woodwork.

Probably generates more lawsuits based on bad communication and over expectations than anything next to injury. 

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12 hours ago, John Harte said:

Yes some form of stain could well be involved.  At least some wetting of the wood structure with varnish or similar seems important in achieving the type of look seen in my photos.  Other factors like wood ageing etc., etc., also seem to make a difference. 

I find that letting the protein ground be the wetting interface introduces adherence issues. The thin clear varnish layer does a nice solid interface as long as it dries thoroughly.
 

Aging is indeed involved. Keep in mind that all natural organic materials degrade to one degree or another. 

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29 minutes ago, Michael_Molnar said:

I find that letting the protein ground be the wetting interface introduces adherence issues. The thin clear varnish layer does a nice solid interface as long as it dries thoroughly.

Maybe that's why the varnish on ancient Cremona violins wore away so quickly and thoroughly?:)

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11 minutes ago, Michael_Molnar said:

Yes, but I think a lean varnish wears faster than a fat one. ;)

The "legends" about pressing a finger on Strads, leaving a fingerprint, and the fingerprint going away in a short time do not suggest a lean varnish. But if these instruments had been "French polished" recently, that would be one possible explanation, even if it was a lean varnish.

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20 hours ago, David Burgess said:

The "legends" about pressing a finger on Strads, leaving a fingerprint, and the fingerprint going away in a short time do not suggest a lean varnish. But if these instruments had been "French polished" recently, that would be one possible explanation, even if it was a lean varnish.

In your capacity as a legendary maker have you tried that fingerprint test? ;)

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20 hours ago, David Burgess said:

The "legends" about pressing a finger on Strads, leaving a fingerprint, and the fingerprint going away in a short time do not suggest a lean varnish. But if these instruments had been "French polished" recently, that would be one possible explanation, even if it was a lean varnish.

Then there is the lack of leaving white scratches, which also points to a fat varnish. 
I find lean varnishes with rather high contents of plasticizers to show these characteristics, too.

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Thank you @John Harte
for the excellent photos.  And again for your explanation of the inner reflection of the wood fibers. This explanation also goes to the spruce, where we see enhanced cross grain reflectivity..."silking". The ground we are looking at must be subsurface in order to create this phenomenon.   Therefore the wetting properties are of equal importance as the reflective characteristics. Surface materials do not give the same depth.  The wood has "color" which I see as part of the aging processes,  not an applied material. Once the ground is established the translucent varnish....properly applied...creates a lens of variable thickness which is a slight magnifier.

I agree with you @Michael Szyper.  The ground will dent before it scratches.

on we go,

Joe

 

 

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