Stradivari's Ground

[David Tseng]

...and on a completely different train of thought

I have been thinking about this for a while now and in the context of occupational risk to the violinmaker, it should be mentioned that the particles in the micrograph might cause very serious health problems long

Amorphous silica particles is not a health hazard. It is present in the drinking water. Only the needle shaped silicon compounds such as fiber glass and asbestos are bad.

[Johnmasters]

I've looked at this Strad Ground image

several times and I'll never "see" any resemblance whatsoever for kaolinite, Calcium Carbonate, or Gypsum mineral.

That particle roundness sure suggests a micro-Silica or silica fume product whose chemical analysis may certainly

include impurities of K, Ca, etc.

Perhaps a volcano [Lipari, Italy] produced a silica fume available to "Antonio", or maybe one of his pals was way ahead of the curve

with vapor phase flame hydrolysis.

I'm not buyin' the suggestion of kaolinite, Calcium Carbonate, or Gypsum mineral.

Jim

In fact, you can buy the West Sytem #406 for fumed silica. Anybody here can try it. Others have also spoken of Porcelana cement.

[GlennYorkPA]

I've looked at this Strad Ground image

several times and I'll never "see" any resemblance whatsoever for kaolinite, Calcium Carbonate, or Gypsum mineral.

That particle roundness sure suggests a micro-Silica or silica fume product whose chemical analysis may certainly

include impurities of K, Ca, etc.

Perhaps a volcano [Lipari, Italy] produced a silica fume available to "Antonio", or maybe one of his pals was way ahead of the curve

with vapor phase flame hydrolysis.

I'm not buyin' the suggestion of kaolinite, Calcium Carbonate, or Gypsum mineral.

Jim

Jim,

LOL

I totally agree with you and glad you said it. I don't see kaolin here either; weathered or unweathered.

I also mentioned, back in another thread, that smoke often consists of submicron particles so I think a volcanic source of finely divided amorphous minerals, is an interesting avenue to pursue.

Glenn

[David Tseng]

I use aged lime paste for ground, no resin binder. I just took it out of the UV box to give it 2 photo shots. One coat of varnish has been hand-rubbed on top of the ground. No trace of ground can be seen.

http://www.flickr.com/photos/d1tseng/3226680084/

[Johnmasters]

I use aged lime paste for ground, no resin binder. I just took it out of the UV box to give it 2 shots. One coat of varnish is applied on top of the ground. No trace of ground can be seen.

http://www.flickr.com/photos/d1tseng/3226680084/

Two photo 'shots' ? Or do you spray it?

[upnorth]

Amorphous silica particles is not a health hazard. It is present in the drinking water. Only the needle shaped silicon compounds such as fiber glass and asbestos are bad.

David, I see from the micrograph that there is no Crystallanity, not even a few percent, and I guess that is how you knew it is amorphous. Do you think it was a natural substance that was available to the alchemist or violin maker or was it calcinated to make it amorphous? And then the question is why would it have been made amorphous.

[Mike_Danielson]

With respect to the Figure 3 which came from the Tai review in the latest VSA Journal, it is important to note that this SEM micrograph came from Nagyvary. I suspect that this is a retouch area in which the restorer used modern materials to repair the varnish, and that would include particulates that reflect modern manufacturing methods.

It is my surmise that Nagyvary's examination of a Strad varnish sample as reported in his article in Das Musikinstrument is also of a retouch.

Provenance of a sample is everything. This topic of a retouch has been discussed before on Maestronet. The work I trust on this issue is Barlow/Woodhouse and the recent work of Echard.

Mike D

[La Folia]

Amorphous silica particles is not a health hazard. It is present in the drinking water. Only the needle shaped silicon compounds such as fiber glass and asbestos are bad.

Not true at all. Either quartz dust or amorphous silica can cause silicosis. This caused the rapid death of a lot of minors after the invention of the jackhammer. In fact, I tried to buy some colloidal silica (for another purpose) but was informed that they were afraid to market it.

However, you can rest assured that the ground that you see on violins is immobilized by the binder. As far as I can see, there's virtually no way you could get a dangerous amount of that material into your lungs.

[Johnmasters]

David, I see from the micrograph that there is no Crystallanity, not even a few percent, and I guess that is how you knew it is amorphous. Do you think it was a natural substance that was available to the alchemist or violin maker or was it calcinated to make it amorphous? And then the question is why would it have been made amorphous.

I can answer for David: to save lives.

[Mike_Danielson]

As far as volcanic ash is concerned, I lived about 200 miles northeast of Mount St. Helens when this volcano blew up. There was 1/4" deep ash everywhere, and I still have a couple of pounds of the ash. This stuff is coarse (though finer than beach sand) but there was a portion that was as fine as talcum powder--you would have to grind my sample to make any use of it as a ground. Of course, there are methods of separation that would allow a finer size cut to be removed.

I think it would be possible to use volcanic ash in the ground by first removing the smallest diameter particles--perhaps by a flotation process. These may require some grinding.

Mike D

[David Tseng]

[ quote from JimMurphy: That particle roundness sure suggests a micro-Silica or silica fume product whose chemical analysis may certainly

include impurities of K, Ca, etc.]

In Barlow/Woodhouse's spectra, Ca is the dominant component. (42/Ca vs 11/Si, I have no idea whether these are atomic or weight concentrations)

As I have mentioned in other thread some time ago, silica particles are made by adding acid to water glass solution. We make this product in the lab to use as a catalyst. As for silicosis, I read somewhere that over a million people suffer from silicosis in the US but very few people die of it these days. If you live near the down-wind side of a freeway, every time someone steps on the brake, asbestos particles would spew out of the brake drum. I don't know if they still use asbestos to make brake shoes.

It has dawned on me, perhaps Sacconi is correct if you do it in the right way. Even Rubio's formulation may work also. The particles could be from precipitation.

[Andres Sender]

Regarding volcanic 'ash'/'smoke'/dust, I haven't found any descriptions of this material which make it seem a likely candidate as a natural source for the particles in the ground.

From what I can discover the low end of the size range for these particles is 1 micron, and the particles have the wrong shape.

Has anyone found information which makes volcanic 'smoke' seem more likely as a source for Cremonese ground particles?

Mike D.--grinding (at least those techniques available historically) is apparently not a way to get the needed particle sizes.

[upnorth]

I can answer for David: to save lives.

What in the wide world of sports do you mean by that! Are you implying that it was known that certain types of dusts caused health problems in those days. Keep in mind that silicosis and other pneumoconiosis type disorders take years or even decades to manifest.

Silicosis is one of the very worse diseases that I have ever witnessed! I am in the health care profession.

How long has amorphous silica been known to exist by that name, and what are/were its common names?

[Bill Yacey]

Perhaps the particles were introduced into oil or water (spirit?) from the liquid being run through an earthen filter, and the fine particles managed to pass through the coarser sand and finer pumice elements of the filter. I built a filter like this with my kid for a science project, and no matter how many times you wash liquid through it, you still get a little tiny bit of particulate in the filtered liquid.

[upnorth]

Regarding volcanic 'ash'/'smoke'/dust, I haven't found any descriptions of this material which make it seem a likely candidate as a natural source for the particles in the ground.

From what I can discover the low end of the size range for these particles is 1 micron, and the particles have the wrong shape.

Has anyone found information which makes volcanic 'smoke' seem more likely as a source for Cremonese ground particles?

Mike D.--grinding (at least those techniques available historically) is apparently not a way to get the needed particle sizes.

I think particulates less than 1 micron are not even effected by gravity. They are floaters like smoke.

MSDS sheets are good information for this kind of information if you take into consideration that some dusts are known to cause silicosis and some are not. Namely, those silicas with chrystalline like structures do. And in order to get silicosis, the particle size must me sufficiently small enough to get into the part of the lung that causes the disease. And that magic number is... around 1 micron ( I need to double check my source on this). I am just thinking out loud here. But your smoke and ash is an interesting thought.

[Johnmasters]

What in the wide world of sports do you mean by that! Are you implying that it was known that certain types of dusts caused health problems in those days. Keep in mind that silicosis and other pneumoconiosis type disorders take years or even decades to manifest.

Silicosis is one of the very worse diseases that I have ever witnessed! I am in the health care profession.

How long has amorphous silica been known to exist by that name, and what are/were its common names?

It was a joke. One can handle fumed silica without inhaling it if one is careful. People who mix it with epoxy to make fillets on boats may have a problem if they use a power sander to smooth it out. They also call it colloidal silica. I did not or do not know if amorphous silica is dangerous. I consider that it probably is. Soluability in lung fluids is likely damned low.

[Johnmasters]

I think particulates less than 1 micron are not even effected by gravity. They are floaters like smoke.

MSDS sheets are good information for this kind of information if you take into consideration that some dusts are known to cause silicosis and some are not. Namely, those silicas with chrystalline like structures do. And in order to get silicosis, the particle size must me sufficiently small enough to get into the part of the lung that causes the disease. And that magic number is... around 1 micron ( I need to double check my source on this). I am just thinking out loud here. But your smoke and ash is an interesting thought.

With brownian motion in air, you could expect an average elevation above ground level to be about kT/2 divided by the mass. That would be thermal randomness. Don't know what this height would be. In water, same thing, I suppose. One could use settling to divide fractions. Milk particles of about that order of size do not seem to filter down, but water is more boyant than air.

[upnorth]

It was a joke. One can handle fumed silica without inhaling it if one is careful. People who mix it with epoxy to make fillets on boats may have a problem if they use a power sander to smooth it out. They also call it colloidal silica. I did not or do not know if amorphous silica is dangerous. I consider that it probably is. Soluability in lung fluids is likely damned low.

Ah ha,

I do know that amorphous silica is not an occupational hazzard that is any worse than general dust. Compared to chyrstalline silica which is very hazardous and special precautions are necessary. But you wont know if it caused a problem for years or decades. Microspheres are not generally hazardous because of their shape.

[Johnmasters]

Ah ha,

I do know that amorphous silica is not an occupational hazzard that is any worse than general dust. Compared to chyrstalline silica which is very hazardous and special precautions are necessary. But you wont know if it caused a problem for years or decades. Microspheres are not generally hazardous because of there shape.

Sanding a ground or any emulsion is something I am careful with, for anything with minerals. But my finishes require very little rubbing. I am still careful, though, I have a good sized chemistry set.

[GlennYorkPA]

Hi Glenn! It's good having you here again!

Cellini, in his "Life", mentions that he was almost killed by diamond powder that was added in a sauce by one of his enemies. He survived because the jeweler who produced it changed the diamond for a less precious stone.

According to Cellini, diamonds can be broken till the powder will not be spotted while the victim is chewing the poisoned food. Eventually, the diamond powder will cut the stomach of the victim, killing him.

When we read the catalog of Kremer Pigment, for instance, there are some intersting materials such as fish scales and many minerals.

Hi Luis,

I'm only here because I spent so long reading those articles in VSA Papers, I felt they deserved a good discussion because I don't know what is really new and what is a rehash of other people's ideas and experiments.

It was very modest of you to tell us an anecdote about crushed diamonds when you achieve one of the clearest finishes on your instruments that I have seen.

Johnmasters, cutting to the chase, do you have a ground preparation containing particles that you feel is similar to the classic grounds? If you do, I can understand your reluctance to reveal the technical details because that should have some financial value to you.

On the other hand, I'm sure many would be interested to see the visual results of what you have achieved. Did you say you might post some pictures for us to look at?

Glenn

[JimMurphy]

[Preface - I haven't seen Bruce Tai's new VSA article yet, so I don't know which SEM images it contains]

With regard to volcanic ash, or pumicite, Barlow/Woodhouse published this image of a different Strad violin

showing larger non-rounded particles:

Now this image seems more indicative of jagged pumicite particles perhaps mixed with a Ca-feldspar or calcium carbonate,

rather than the smaller rounded particles [silica fume ???] shown in the previous image of another Strad violin

[courtesy Nagyvary].

Jim

[Edit: added Ca-feldspar]

[Andres Sender]

Jim, given the scale shown on that photograph, it looks like many of the particles we're interested in would be at or below the resolution of that particular instance of the picture.

[Johnmasters]

Johnmasters, cutting to the chase, do you have a ground preparation containing particles that you feel is similar to the classic grounds? If you do, I can understand your reluctance to reveal the technical details because that should have some financial value to you.

There is no money in it for me. But I have had it suggested that I give a seminar. This person mentioned that Gary Bease charged $2500 to teach about varnishes that came from old literature. I think that was good money. Maybe I can get at last a few thousands.

I said several times what my complaint was. I also think I gave at least 99% of the details in the actual postings. Nobody read them. Or nobody read them very carefully. At one point I said I was 98% finished. Then I made another post and said 99%. I can't remember if I gave the final 1%. In any case, I don't want to spoon-feed anyone by summarizing a method and giving recipes. (You need TWO recipes as I said several times) Please read those postings if you are interested. Then ask a question... the question should not be "can you explain blow by blow?" It should be more like "what properties should a surfactant have, and why is casein not a surfactant?"

On the other hand, I'm sure many would be interested to see the visual results of what you have achieved. Did you say you might post some pictures for us to look at?

The particles are on the order of size discussed, I can tell from the rate of sedimentation of them in water. It may or may not be like a classical ground. I have read the Woodhouse/Barlow paper and the elements vary. If some say Calcium Sulfate, or calcium carbonate, I have not tried them because I expect they would be more opaque than what I use. But yes, I should try them. It would take until tomorrow evening. I have tried numerous silicates and have chosen the one most clear. It is virtually transparent in varnish on a glass slide. If Strad did not use this, then he is at fault. At least, at fault if mineral fillers in an emulsion varnish are what he wanted to use. Sorry to be so proud, but there is no sin in improving a good idea.

Yes, I will post photos soon. I am finishing up the violins with lean over fat. As it works very well. (Does anyone know why?)

The problem with pictures to prove a point of worthiness is that people may not like the looks of my varnish. My goal is to have a perfect film that is very thin and also colored. Sometimes the color is deep. There are a couple of shaded ones with intense red. Don't like that? Well anything can be cut back. It is just a demonstration. Besides, I like red. They in fact are likely to look too commercial to some. They do not have surface defects. But they have an advantage over commercial varnishes that look the same. That is, they are not spirit or lacquer. They dent rather than chip, even though a lot of people want "chip." I want it to stay the same as long as I can see it. There are some nearby that have been used a few years and still look like new. I know people don't like "new," that is just me.

Jeffrey: things have improved a lot since the viola you sent back. I spent the last three months refining things and getting rid of a few bugs. Also changed a lot of formulations. I can do this because, as I said, the system is very versatile.

Glenn

[Bill Yacey]

Depending on what concentration of particles there is, it could even have been introduced by airborne dust. In reading a makers forum in a back issue of the VSA journal, it was said in the old days linseed oil was polymerized out in the open sun in shallow trays with a cheese cloth or similar covering. This would prevent larger airborne particles and insects from getting into the oil, but finer dust would get through readily enough.

Seeing how it is estimated this was left out exposed for up to 3 weeks, it could have accumulated a fair amount of particulate from road dust, wind borne volcanic dust or the missus down the street sweeping dirt off the walkway in front of the house. The majority of it would eventually settle out and be left behind as dregs, but the finer particulate would remain in suspension indefinitely. Could it be possible this is what is being found through analysis, or are the concentrations too high to be introduced in this manner? Maybe specifically the dregs were found to be useful as a filler/ sealer.

[Bruce Tai]

I've looked at this Strad Ground image

several times and I'll never "see" any resemblance whatsoever for kaolinite, Calcium Carbonate, or Gypsum mineral.

That particle roundness sure suggests a micro-Silica or silica fume product whose chemical analysis may certainly

include impurities of K, Ca, etc.

Perhaps a volcano [Lipari, Italy] produced a silica fume available to "Antonio", or maybe one of his pals was way ahead of the curve

with vapor phase flame hydrolysis.

I'm not buyin' the suggestion of kaolinite, Calcium Carbonate, or Gypsum mineral.

Jim

It is quite obvious that these particles are still surrounded by organic binders.

I am not sure what kaolinite, calcium carbonate and gypsum should look like when they are about 1 micrometer in diameter and wrapped in organic binders. If mica was used, we would expect flaky appearances.