Stradivari's Ground

[Marijan Radaljac]

John,

when you talk about two recepies, may I pressume that you are saying that internal (lypofilic/emulgator)and external/water phases both require a formulation (recepie) that will result in wanted emulsion. Oil varnis for examp., emulssifier and aditional substances?? would be a first recepie, water, surfactant, particles would be the second one.

Technology of dispersion making (shaking, blending, mixing.....) is a part of a "recepie" to?

[FiddleDoug]

I'm not an expert on varnishes or grounds, and, in fact, have never varnished an instrument. (Hope to build an instrument or two someday!) My background is in the sciences (analytical chemistry). I've been following this thread (and other varnishing threads, and Nagavary's work), and I don't think that I've seen any reference to my own "pet" theory. There are naturally occurring colloidal mineral particles in any area of the world that has mountains with glaciers (like the Italian Alps). These are in the form of glacial "flour", or silt. As a glacier moves over rock, the trapped rocks grind against each other, and creat the rock flour. As this is washed out of the glacier by melt water, it forms milky looking streams with suspended minerals. Quieter backwaters downstream would allow some of this rock flour to settle as a silt, that might have the micro-particulate, and mineral properties of the mystery ground.

This is just my theory, and if anyone has proposed this before, please give me a reference, so that I can see what research on this looks like.

If my theory is new, and anyone runs with it, please give appropriate credits.

Let me know your thoughts on this theory!

[FiddleDoug]

Just did a further search and found that Andres Sender has previously mentioned the possibility of rock flour here on MN. Probably some others as well.

[Oded Kishony]

There are two traditional surfactants mentioned in the literature. One is ear wax (yuk) the other is ox gall which can be purchased at most art supply stores. These materials are used to reduce surface tension of water and other liquids. It's possible (speculation approaching) that alcohol can also be used as a surfactant since it is miscible with water and has lower surface tension.

~OK

[JimMurphy]

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

Hi Bruce,

Yes, and upon further zoomnification [] of these particle agglomerates, I've been under the impression

this same Strad sample is where ~200nm rounded particles were revealed.

Jim

[Johnmasters]

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.

The particulates must be in the water phase, not the oil phase.

[Johnmasters]

John,

when you talk about two recepies, may I pressume that you are saying that internal (lypofilic/emulgator)and external/water phases both require a formulation (recepie) that will result in wanted emulsion. Oil varnis for examp., emulssifier and aditional substances?? would be a first recepie, water, surfactant, particles would be the second one.

Technology of dispersion making (shaking, blending, mixing.....) is a part of a "recepie" to?

Thanks for thinking about things, that is really all I want. Yes, certainly, you are right. The easiest, most practical, most reliable, and completely adequate approach is to make each of the two phases separately. The acqueas (water and external phase) with a protective colloid. The minerals are here also. That is implicit in Harris; the particles and wood are both wet with water and the oil droplets are drawn in.

The oil phase is made separately. It has the "surfactant".

The mixing is part of a recipe, sorry for the evasion of this responsibility. The water is added to oil slowly while mixing. It will initially be W/O until it becomes unstable (too much interior phase, droplets, can close-pack only to a limited degree.) At this point the emulsion inverts to the O/W which is desired. I suspect that the Harris approach will not invert. I have tried incomplete formulations (casein only, no surfactant) and could not get an inversion. At best, there is the instability that Harris mentions.... Large drops of water "leak" out. Inversion is important. It is a well-known way to get SMALL droplets in an emulsion. This fact has to do with detailed properties of the two surface tensions. It works because there is a Surface Acting Agent. ("surfactant")

There are much more elaborate emulsions. For edification, next time you are at the supermarket, read some contents on various cosmetic lotions. Most of the things are concerned with making emulsions, they are at the end of the list because they are in lower concentration than the main ingrediants. (Which are cheap things like water, mineral oil, etc) I truly think that any interested person should do this simple excercise of reading the contents of cosmetics stuff. It is a world of information. You might even Wikipedia a few things.

I have kept the surfactants to one only. It is in the oil phase, has a low HLB, is a mix of phospholipids, exists in nature, was present in Cremona since early times etc etc. I kept it simpler than a difficult cosmetic because it had to be easily discovered by an early worker.

However, it is one step beyond Harris because it in fact has a surfactant. (no pun intended) Casein is not a surfactant and neither is gellatin (glue).

That is all of it.......... I even mention the inversion here. The only thing not discussed in Wikipedia is emulsion inversion, but you can find a university chemistry libarary which will give plenty of information emulsions or, more specifically, on emulsion coatings.

[La Folia]

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.

1. It all depends on the silica and how it is prepared. Some amorphous silica might be OK, I don't know. As far as I know, it depends on unsatisfied bonds on the surface. I'm pretty sure finely ground silica--whether amorphous or crystalline--is very hazardous. If it's not ground, well, maybe not. If you breath this stuff, do your own research on it.

2. The speed of getting silicosis depends on the dose. If you operated a jackhammer in a mine, it could kill you in a couple of years. Your dose when looking at a violin ground would be zero. Your dose when working with dry, colloidal silica, is somewhere in between.

3. Silica is not asbestos. The hazards are distinctly different. Asbestos is legally defined, roughly, as anything longer than it is wide--and that's just as dumb as it sounds. Some mineral forms of asbestos are not particularly dangerous. Asbestos has not been allowed in brake linings for many years.

[Bill Yacey]

The particulates must be in the water phase, not the oil phase.

That's assuming an emuslion was used. I am sure you know much more about this than I do, but I recall reading that microtomed samples indicate distinct different layers of protein and oil/resin at the ground layer; although an emulsion isn't required to contain proteins, is it?

In my previous post it just came to mind that perhaps the particulate wasn't intentionally introduced, but more of a residual component from some other preperatory process.

[Johnmasters]

That's assuming an emuslion was used. I am sure you know much more about this than I do, but I recall reading that microtomed samples indicate distinct different layers of protein and oil/resin at the ground layer; although an emulsion isn't required to contain proteins, is it?

In my previous post it just came to mind that perhaps the particulate wasn't intentionally introduced, but more of a residual component from some other preperatory process.

I usually put a coat of casein on the top first, it is not absolutely necessary, but I find that white violins with only casein, before any varnish, sound more clear and focussed than white violins without. Harris does not like even casein in the wood. I think he is not a violinist.

Yes, a protective colloid is needed in the water phase of an emulsion except in the case of very sensitive adjustments of more than one surfactant. This is laboratory work, and not straight-forward. Glue is an alternative, casein seems better. A father of emulsion coatings told me "stick to casein" when I asked him. He was in his 90's.

Particles may be present as stabilizers if emulsions evolved for this use. They could also be intentional as fillers.

Strad may not have used emulsions at all. But the discussion here is about "what if he did." You can also put a slurry of something on the wood first as others have been doing for a while now.

[Marijan Radaljac]

It is in the oil phase, has a low HLB, is a mix of phospholipids, exists in nature, was present in Cremona since early times etc etc.

Thank you John for extensive answer.

I hope you didn`t have to kill to get that natural surfactant .

How did you determine HLB needed to get a stabile emulsion. By calculation or by trying. I supouse you are using a blender or something to go through the mechanical phase of dispersion. Did you find it usefull to heat both phases before joyning them together?

[GlennYorkPA]

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.

Ferbose,

The point of the Harris, Sheldon article following yours in VSA Papers was to recreate the Cremonese ground and show what it looks like microscopically. Hence their Fig 5 on p155 shows an electron micrograph of an oil in water emulsion stabilized with kaolin clay. Kaolin consist of hexagonal flakes and, indeed, in their photographs, the flakes can be seen and don't at all resemble the ground you showed in your Fig 3.

I assumed that you were working with these guys and that's why the papers appeared together. Is this not the case?

Glenn

[Johnmasters]

Thank you John for extensive answer.

I hope you didn`t have to kill to get that natural surfactant .

How did you determine HLB needed to get a stabile emulsion. By calculation or by trying. I supouse you are using a blender or something to go through the mechanical phase of dispersion. Did you find it usefull to heat both phases before joyning them together?

Room temperature.... I see no reason not to heat, and a very good one. If one had a thick varnish (an old maker might want to save money on solvent) One could use heat and this would not damage any components. Once the oil was in droplets, after inversion, they are hard balls. The only question would be the size of the droplets. But it should work fine. I have not tried this because solvents are cheap. Besides my vernice comes thinned.

I have tried several surfactants. Look to nature. It is full of surfactants. If I killed, likely I could find many in the human body. It is more kind to get it from plants, however.

I use a simple milkshake mixer, cheap home variety. I also use a collection of nice uniform-sized Nalgene (250 cc) bottles which are convenient. They cost about $100 per 50 units.

I will postpone revealing the surfactant until some more discussion. It is not a secret, but see what you can learn from Wikipedia using the obvious catch words and their links. The first person to make a good guess gets a pat on the back. The one who guesses the actual surfactant gets a "good for you !"

[Johnmasters]

Ferbose,

The point of the Harris, Sheldon article following yours in VSA Papers was to recreate the Cremonese ground and show what it looks like microscopically. Hence their Fig 5 on p155 shows an electron micrograph of an oil in water emulsion stabilized with kaolin clay. Kaolin consist of hexagonal flakes and, indeed, in their photographs, the flakes can be seen and don't at all resemble the ground you showed in your Fig 3.

I assumed that you were working with these guys and that's why the papers appeared together. Is this not the case?

Glenn

I guess you all know that the Chinese invented porceline centuries before Europe discovered how to recreate it. "Kaolin" is a corruption of the Chinese "top of the mountain." It must be one hell of a corruption, because I asked my Chinese wife what "Kaolin" meant, and she did not know what I was talking about.

This was clay found at the top of the mountain. Perhaps the large particles seeped downhill. It is also used to size magazine glossy paper. It would have been present in Europe by that time. Especially in Germany. I wonder why the German makers did not use it.......

[Johnmasters]

Here is a violin I got back from the Wheeling school system. They have had it for 3 years. It shows no wear, but it has been used a bit.

Here are more recent ones.

The newer samples not yet finished have some improvements. I am as yet undecided on using an additional step which illuminates the wood slightly better.

[upnorth]

John nice varnish!

I once made a ground from Bees wax and other things. It was very nice looking but I needed a barrier between it and my varnish which was membrane-like for the varnish to stick, and it was very fragile.

[Johnmasters]

John nice varnish!

I once made a ground from Bees wax and other things. It was very nice looking but I needed a barrier between it and my varnish which was membrane-like for the varnish to stick, and it was very fragile.

This particular varnish is very durable. The entire method is extreamly versatile, and nearly anything can be done.

[La Folia]

This was clay found at the top of the mountain. Perhaps the large particles seeped downhill. It is also used to size magazine glossy paper.

It has nothing to do with particle size. Kaolin is formed by intense chemical weathering, under conditions of high rainfall. Essentially everything is dissolved away except for aluminum and silica, and this aluminum silicate clay forms. Under even more intense weathering the remaining silica washes away and you get bauxite (aluminum hydroxide). Being at the top of the mountain speeds the process by promoting rapid groundwater flow.

[GlennYorkPA]

Here is a violin I got back from the Wheeling school system. They have had it for 3 years. It shows no wear, but it has been used a bit.

Here are more recent ones.

The newer samples not yet finished have some improvements. I am as yet undecided on using an additional step which illuminates the wood slightly better.

Very good!

Now, HANDS UP ALL THOSE YOU CAN LOOK AT A VIOLIN AND SAY WHETHER IT HAS A CREMONESE GROUND OR NOT.

If you truthfully can, then either you already have a lucrative career in violin authentication or such a career awaits you.

Glenn

[Bruce Tai]

Ferbose,

The point of the Harris, Sheldon article following yours in VSA Papers was to recreate the Cremonese ground and show what it looks like microscopically. Hence their Fig 5 on p155 shows an electron micrograph of an oil in water emulsion stabilized with kaolin clay. Kaolin consist of hexagonal flakes and, indeed, in their photographs, the flakes can be seen and don't at all resemble the ground you showed in your Fig 3.

I assumed that you were working with these guys and that's why the papers appeared together. Is this not the case?

Glenn

I was not aware of the Harris article at all. If I had consulted with them, I would have mentioned in my acknowledgment.

Bruce

[Andres Sender]

John, is your surfactant a gum?

[fiddlecollector]

John, is your surfactant a gum?

Sounds like Lecithin to me,i thought you didnt care for it?

[Johnmasters]

It has nothing to do with particle size. Kaolin is formed by intense chemical weathering, under conditions of high rainfall. Essentially everything is dissolved away except for aluminum and silica, and this aluminum silicate clay forms. Under even more intense weathering the remaining silica washes away and you get bauxite (aluminum hydroxide). Being at the top of the mountain speeds the process by promoting rapid groundwater flow.

Thanks, aluminum silicate is good............... Magnesium silicate is better yet. If Strad did not use it, that is his problem.

[Andres Sender]

Sounds like Lecithin to me,i thought you didnt care for it?

He's said previously that he never got it to work.

I'm thinking it's either a gum, or, since he may be using it in the oil, some type of soap?

[Johnmasters]

Sounds like Lecithin to me,i thought you didnt care for it?

"Good for you!" I have had it around a dozen years. I went to Span-80 but decided finally that the main thrust of the whole argument had to be something doable by ancient workers. Span-80 is modern of course. The phospholipids work extreamly well. Before, I discarded the idea after trying to dissolve it in water. That was a long time ago. It is oil soluable. Try 2% in oil.