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Ground color ?


AndreaA

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"golden ground" does not do it justice. The color is subtle, complex, elusive.

A point of interest: organic compounds from nature rotate polarized light in one direction (right) while synthesized compounds rotate it in the opposite direction (left). Is this property visible to the naked eye? Don't know. It's intriguing though.

Oded

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"golden ground" does not do it justice. The color is subtle, complex, elusive.

A point of interest: organic compounds from nature rotate polarized light in one direction (right) while synthesized compounds rotate it in the opposite direction (left). Is this property visible to the naked eye? Don't know. It's intriguing though.

Oded

I have some orpiment from Kremer. I have never heard it discussed. Rather poisonous, arsenic sulphide. Has anyone used it?

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"golden ground" does not do it justice. The color is subtle, complex, elusive.

A point of interest: organic compounds from nature rotate polarized light in one direction (right) while synthesized compounds rotate it in the opposite direction (left). Is this property visible to the naked eye? Don't know. It's intriguing though.

Oded

Interesting you would mention that. I was just reading an old document that had some information about the optical rotatory values of various substances. I was wondering if it might be that the closer that value is to zero the better the optical effects of a varnish for example. If the value is high + or - would that mean that it blocks some light transmission like a polarized filter? Just guessing here, I know just enough to be dangerous. I would think that rotation would not be different in a nature made vs a lab made compound if it is the same compound? For example if you synthesize water by mixing some H and some O then it is still water just like the natural stuff?

Orpiment: It's toxic but you're not going to snort it. Ancient calligraphers used it in illuminated manuscripts and apparently they lived long enough to do the illumination. well heck, even the above mentioned dihydrogen monoxide can kill you.

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"golden ground" does not do it justice. The color is subtle, complex, elusive.

A point of interest: organic compounds from nature rotate polarized light in one direction (right) while synthesized compounds rotate it in the opposite direction (left). Is this property visible to the naked eye? Don't know. It's intriguing though.

Oded

Oded sorry but this is completely wrong. :) Natural substances can exist in any type of enantiomer (+ and -, or Dextrorotatory and Levorotatory).Many are non optically active.

For an classic example of a synthetic substance take Thalidomide, the + type is used even now for treating leprosy and malignant melonomas. The - type causes birth abnormalities. When they first synthesized it they gave patients both types ,it used to be very difficult to seperate the two types as most of their physical properties are identical. When many organic materials are synthesized they often end up as whats called a Racemic mixture ,containing 50%/50% of each enantiomer. This was named after experiments by the German scientist Scheele who discovered a substance on wine fermenting barrels/corks that he called Racemic acid ,which had the same structure and chemical formula as tartaric acid.

Racemic mixtures are optically inactive .

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I second Fiddlecollector on that, and the thalidomid example is unfortunately a very tragic one. On a lighter note, Pasteur who was very fond of wine manually separated crystals of tartaric acid coming form in vitro synthesis and showed that each enantiomer had opposite effect on polarized light.

But if I understand correctly, and since the solar light is not polarized, no real direct effect of a varnish should be seen because even if some of its components were to be chiral and able change the rotation plan of the light it receives. the effect has to come from reflection, refraction index and other physical properties of the layers.

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I was curious to see what a instrument would look like if it was to have a golden ground applied to all of the instrument with the exception of the top and bottom plate corners as well as not applying in the wear patterns on the back.I would like to get opinions .

This is an unusual request in any case.

Most antiquers I know, try to obtain a ground that can be observed on the parts of the violin you are specifying, once the varnish itself has been worn off (either naturally, by time, or intentionally, as an antiquing *device*) - leaving only the ground and the appearence of something on the wood other than new bare white wood, since that (having bare white wood) obviously doesn't work for those areas where one would normally find the wear patterns on ligimate old violins.

?

Oh, by the way, welcome to Maestronet!

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my apologies. such a lovely idea-it ought to be true :) I must have picked this piece of information somewhere. Could it be that I over generalized and this could be true about natural vs synthetic/manufactured colors?

Oded

But you were right in the sense that for example in nature all the amino acids are synthetised as a single enantiomer (the L one, even though this denomination has nothing to do with its effect on polarized light, left or right) because (and that's what I was taught) they are synthetized by enzymes that are themselves chiral molecules. If you were to make the same amino acids in vitro, chemically that is, chances are you would get a mix of each enantiomer (and not necessarily 50%-50% since chemists will tell you that some reactions can favor one product over the other). the same could happen with some organic dyes indeed but only if they possess at least 1 chiral carbon (that is a carbon linked to four different groups). And as I mentioned Pasteur earlier, tartaric acid synthetised naturally can change polarized light, but when you get it synthetized in a tube, it does not affect light because it's a 50-50% mix of each enantiomer, the ones Pasteur separated.

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Responding to the question about orpiment: I remember reading an old VSA Journal article (sorry I can't quote the reference specifically right now) that claimed to have identified arsenical material in a classic instrument (or maybe it was a few instruments-I seem to remember a cello) and speculating that the golden appearance was a consequence of orpiment solution applied to the wood-perhaps to inhibit woodworm activity. Since there is arsenical sulphide mined near Salt Lake City, this was a lively topic of speculation for a while when I was at school there. Certainly orpiment was a widely used yellow-gold pigment and would have been available to the classic makers. Beyond that the subject seems to have received little attention in recent years. The toxicity is an obvious objection to its use.

Doug

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Hmm. There are some points needing clarification and agreement or consensus on those clarifications. :D

First, I thought that the Cremonese wood was "white" for starters, but with age took on a darker "golden red-brown" hue. Please correct me.

Second, I thought the strong golden brown some makers may add to the ground of their new "in-the-white" instruments is intended to "age" the wood and also help enhance the "dichroic" look of their varnish. Again, please correct my notions. :)

Third, if the above statements are correct, then I would imagine that the Cremonese Masters did not strongly color their ground with a golden red-brown. Again, please correct me.

Obviously, I set the stage for Joe Robson who has some experience in this matter. ;)

Stay Tuned.

Mike

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Third, if the above statements are correct, then I would imagine that the Cremonese Masters did not strongly color their ground with a golden red-brown. Again, please correct me.

Stay Tuned.

Mike

On the other hand, since the Cremonese didn't leave details, and no one knows for sure exactly what they did - how can anyone correct you on these points, since no one here knows - and they can only present their best guess.

Though I believe that many people will claim a "golden" ground, and do not stipulate red-brown properties to the ground, but perhaps the varnish itself.

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I guess the tricky word here is "color." I have "color" in my ground (raw blonde shellac). The golden cast is not added color as far as I know.

I have noticed that garnet shellac and other darker shellacs do stain the wood (I've stripped my own instruments coated with colored shellac), so worrying about pigments hitting the wood is a concern in those cases.

Do Mfgs add pigments to the darker shellacs?

Well, anyway... I use blonde shellac as the base, unless I want an older muted wood look, which sometimes requires smoky pigment applied directly to the wood.

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Do Mfgs add pigments to the darker shellacs?

Well, anyway... I use blonde shellac as the base, unless I want an older muted wood look, which sometimes requires smoky pigment applied directly to the wood.

I believe that "colored" shellacs are simply less refined than the blond.

I too like the gold-ish or amber-ish tint of blond shellac, but have moved to amber or garnet when I want more ground color to start with.

In order not to contact the wood itself - they can go on after a thin blond coat.

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Now I will ask 2 silly questions regarding the ground.

1) One of the functions of the ground, if I understand, is to prevent colour to get into the wood so that you don't get blotching. So on the violin I am varnishing now I used shellac to seal the spruce and I get now a very even colour from the varnish. No colour seemed to have penetrated the wood. It's very clean, very even,... very boring. On the other hand I put some linseed oil on a scrap of spruce and covered it almost immediately with some of the varnish I am using. Because there is some (I guess) petroleum solvent in the varnish some colour got into the wood (bad sealing) so that there is some blotching effect (not much). But this is so much more appealing for the eyes. So the first question is: Is it really important to get rid of all the blotching effect?

2) Were the old masters aware (or bothered) that their varnish would wear out so that they needed a ground that in addition to prevent blotching it would also have to be more resistant than the varnish? In other words is the resistance of the ground a happy surprise or deliberate?

post-29661-0-66889200-1313952499_thumb.jpg

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Anyone who works with wood for more than a few years can pick up on the notion that different woods soak up finish/fluids differently. I am certain that the old masters were aware of the benefits of priming wood before staining or varnishing. The uneven result of staining would highlight the potential issue for them.

Granted there is a lot to be said for thinking 100 years into the future (or a few hours into the future for the best visual result), you can do whatever you want. If you like blotchiness now, go for it. I don't know what your violin will look like in 100 years. Hopefully, mine will look better. ;) But then again, what looks good is debatable.

All layers on the violin are for protection, so I wouldn't say that the ground is specifically for wear protection, but it does help. The nice visual result of wearing down to the ground might have been less of a happy accident. I've made instruments with raw dark varnish without any ground (as mentioned above), and once wear goes beyond the layers of dark, you hit very white wood, which doesn't look that nice. The same thing happens if any kind of polishing is done. The result looks really bad if you hit bare wood. Granted, you can make the same mistake with a ground present.

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the idea that stradivari had no idea his varnish would wear so much or how it would wear etc doesnt make any sense to me, having worked in nicolos worshop he obviously had access to much older andrea amatis and da salos maybe, obviously hed seen the effects of wear on these instruments, and seemed to know it was important to have a thin stronger undercoat as he must have known time would expose this undercoat from wear IMO

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the idea that stradivari had no idea his varnish would wear so much or how it would wear etc doesnt make any sense to me, having worked in nicolos worshop he obviously had access to much older andrea amatis and da salos maybe, obviously hed seen the effects of wear on these instruments, and seemed to know it was important to have a thin stronger undercoat as he must have known time would expose this undercoat from wear IMO

At least we agree on this! that gets us back to Echard's paper.

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If Strad knew the varnish would wear and that he would need a thin stronger undercoat then why use varnish? Why not use the same undercoat material with some coloring added as the whole finish? Something there doesn't make sense. Unless there is something about the ground that makes it not be a good finish coat? hmmm...

On blotchiness... I kind of like that look too rather than a smooth uniform blandness. I got it by accident. Using amber shellac as the ground I tried to get it very even but it came out somewhat uneven so the varnish layer is not blotchy but the ground is and it's not a bad looking effect.

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Has anybody ever tried this on a plate that had been arched but not yet hollowed. I know Don is using microwaved wood but that might get some different results. I know it looks stupid, but at least it would not leave any trace detectable by microscopy or MS or X-ray spectroscopy, and it would give some brown-amber colour... :)

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Has anybody ever tried this on a plate that had been arched but not yet hollowed. I know Don is using microwaved wood but that might get some different results. I know it looks stupid, but at least it would not leave any trace detectable by microscopy or MS or X-ray spectroscopy, and it would give some brown-amber colour... :)

If you got it too hot wouldn't it melt the glue and the center seam would come apart?

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