Johnmasters Posted January 25, 2009 Report Posted January 25, 2009 Wow. How generous of you. I will send you some. Hope you are not swamped. No I am not swamped, I just wrote this out 8 hours ago. The reason I am confident is that two things are required. The viscosity of the inner phase has to be greater than that of the outer phase. Also the surface tension has to be less. This is what they say in the introduction to a book on emulsions. I have a surfactant that almost certainly was known long ago to adjust any HLB problems. Nearly all oil varnishes are lower in surface tension than water. To keep the viscosity reasonable, be sure you don't send some extreamly thinned out product. It should be about as viscous as a commercial oil varnish, perhaps slightly less. It will take me more time to go to UPS than to do the experiment. But I need an excuse to ride the bike, so it is OK. PS, I am not interested in your particular varnishes, any vernice will work and I think Ace Spar Varnish is just fine.
Johnmasters Posted January 25, 2009 Report Posted January 25, 2009 It certainly is generous of John to volunteer his services but frankly I don't see what the fuss is all about, you slowly add the resin, oil or varnish to the liquid with emulsifier (glue, gum arabic, casein, egg, burnt honey etc), stir (with a stiff brush is better) until they combine into an opaque liquid. You can control how thick it is , from mayonnaise to water, by diluting with water. The worse that can happen is that it won't succeed and you throw it out-it won't set your house on fire, or drive you out with horrible smells or explode It isn't any more difficult than making chocolate milk (which also contain emulsifying agents) IMHO Oded Oded, when you used the word 'emulsifier', I already knew that you did just this. It was amongst my first experiments a long time ago. I discarded it as inadequate. That is why I said to avoid the word. You are leaving out what is perhaps the most important step. With all the discussion of milling minerals to a proper size, you neglect the size of the droplets of oil varnish. Small droplets are VERY stiff, and they will compete with minerals. Likely the wood and minerals will not be suficiently wetted to give the transparent effect desired. The art books talk about gesso etc made this way, with emulsifiers. That is fine for them, they want an opaque gesso. A violin maker wants a transparent gesso, but more than that. The gesso has to properly wet the wood. I would tell you the critical step and why it works, but since you are confident in your methods, I think I will not do so. I have also mentioned at least a half dozen times how to make oxyturpentine varnishes safely. (no exothermic reaction)
GlennYorkPA Posted January 25, 2009 Author Report Posted January 25, 2009 Glenn, Are the minerals infered from elemental breakdown or by actual x-ray diffraction or some other method to find particular crystal types? ______________________________________________________________________ John, VSA Papers contains 40 pages of text and pictures devoted to the topic of Cremona finishes but, in answer to your question, I think the answer is best illustrated but this image, Fig 3 in Bruce's paper. It is an SEM of the ground layer from a Strad sample. I don't think there can be much doubt this is showing highly compacted particles with a size distribution ranging from 0.2 to 2 microns. A frustration I have is the lack of disclosure about where the samples came from on the instrument. Some say the ground penetrates the wood and others say it does not but the extent to which it penetrates the wood will depend on whether it is over open pores or not. As to the nature of the particles, Harris & Sheldon state: "From our observation of the of the pictures made ny Barlow & Woodhouse and the accompanying EDAX analysis, we suspect that the particlesare of soil type minerals that have undersgone weathering, possibly various clays and silicaceous material. Although clay particles, particulaly kaolinite, generally have a flat, plate-like morphology, weathering tends to blunt the corners of the plates." Glenn
Johnmasters Posted January 25, 2009 Report Posted January 25, 2009 John,VSA Papers contains 40 pages of text and pictures devoted to the topic of Cremona finishes but, in answer to your question, I think the answer is best illustrated but this image, Fig 3 in Bruce's paper. It is an SEM of the ground layer from a Strad sample. I don't think there can be much doubt this is showing highly compacted particles with a size distribution ranging from 0.2 to 2 microns. That is the size I expect to see in the minerals I use. I intend to do an experiment using settling as per Stokes Law. The actual stuff I have settles very slowly. The upper portions become opalescent as one expects as the particles get smaller than a wavelength of light. The overall appearance is white, as expected for 1-2 micron size (as in milk). A frustration I have is the lack of disclosure about where the samples came from on the instrument. Some say the ground penetrates the wood and others say it does not but the extent to which it penetrates the wood will depend on whether it is over open pores or not. That is why N was interested in fungi treatment and ponding of wood. As to the nature of the particles, Harris & Sheldon state: "From our observation of the of the pictures made ny Barlow & Woodhouse and the accompanying EDAX analysis, we suspect that the particlesare of soil type minerals that have undersgone weathering, possibly various clays and silicaceous material. Although clay particles, particulaly kaolinite, generally have a flat, plate-like morphology, weathering tends to blunt the corners of the plates." If I go about 1/3 the way from the center of the photo to the upper right-hand corner, I see ONE squarish particle. The rest look like amorphous glop, not crystals. They may be worn crystaline material, but I am guessing that they are not. The chemists should know what this is. The reason I asked about identifying crystals with x-ray defraction is that I am not convinced that they are particular minerals that have names like gypsum or quartz. Perhaps the researchers found only metals as in the SEM experiments. Glenn
David Tseng Posted January 25, 2009 Report Posted January 25, 2009 Late David Rubio also formulated a ground coating based on Barlow/Woodhouse findings. He did not use any resin binder.
fiddlecollector Posted January 25, 2009 Report Posted January 25, 2009 Glenn, research ive seen on Venetian paintings from the same era or before says that they often contain uniformly shaped glass particles of very narrow size range.Usually around 3 to 5 microns.There was no explaination how they produced these particles though.
Johnmasters Posted January 25, 2009 Report Posted January 25, 2009 Glenn, research ive seen on Venetian paintings from the same era or before says that they often contain uniformly shaped glass particles of very narrow size range.Usually around 3 to 5 microns.There was no explaination how they produced these particles though. You would not likely stumble on it with random experiments. But reading is helpful. Fortunately, today we have Wikipedia which can tell you nearly anything. read this and let me know when you have done so. If two or three others read it and reply, I will give the next link. http://en.wikipedia.org/wiki/HLB Go to link in first definition.
Oded Kishony Posted January 25, 2009 Report Posted January 25, 2009 Likely the wood and minerals will not be suficiently wetted to give the transparent effect desired. Adding the oil,resin etc slowly and wisking with a stiff bush breaks up the oil and combines it with the surfactant very well. Likely the wood and minerals will not be suficiently wetted to give the transparent effect desired. rubbing the emulsion on the surface help to transparentise the film and assures complete wetting of wood and minerals. But I'm quite sure that there are a number of different ways to successfully make and apply emulsions. I would tell you the critical step and why it works, but since you are confident in your methods, I think I will not do so. Well, I don't know why you would choose to withhold a 'critical step' from me-and presumably everyone else-because of something I've written. I can live with that. And being a believer in the 'golden rule' (treat others the way you want to be treated) I'll assume that you want me to withhold any 'critical step' that you might be missing in the future. I can live with that too. Oded
fiddlecollector Posted January 25, 2009 Report Posted January 25, 2009 If you look about 3 pages down on ths document you will see a typical scanning electron micrograph of a gesso ground.Notice the scale at the top which is 200 microns.The top layer is fine gesso, the lower layer is courser.The micrograph of the Stradivari ground particles are extremely small compared to it.The lower layer is anhydrous calcium sulphate probably in a glue binder ,the upper layer is pure gypsum.Ucellos Battle of Romano
Johnmasters Posted January 25, 2009 Report Posted January 25, 2009 Adding the oil,resin etc slowly and wisking with a stiff bush breaks up the oil and combines it with the surfactant very well.rubbing the emulsion on the surface help to transparentise the film and assures complete wetting of wood and minerals. But I'm quite sure that there are a number of different ways to successfully make and apply emulsions. Well, I don't know why you would choose to withhold a 'critical step' from me-and presumably everyone else-because of something I've written. I can live with that. And being a believer in the 'golden rule' (treat others the way you want to be treated) I'll assume that you want me to withhold any 'critical step' that you might be missing in the future. I can live with that too. You don't have a surfactant in casein. And I am not being selfish. I am not "witholding" indefinitiely. Read both the threads. Yes, physically rubbing the mayonaise will help (through sheer) break up droplets. If it works, you should be using it on all your violins and don't worry about these threads. The problem with this method is rubbing down, perhaps. I have not tried it. I also don't know what happens when the water and solvent leave. For all I know, the wood never gets completely wetted with oil varnish. Here is why I seem so irritated: Do you recall Bush's heavily redacted report on Global Warming? He got away with it because of the almost zero understanding of and respect for science in our culture. The other day, I heard Hannity speak of the "Al Gore myth of global warming." Many people actually believe it is a politically-motivated myth. Jesus Christ! Can you believe it? Worse yet, DO you believe it? Everyone knows where Rush Limbaugh is coming from. Hannity is more dangerous because he lies about things that people are not always aware of. The future of the Republic is in the hands of whoever can bludgeon the unwashed masses into understanding a few rational things. I would like to lead people to this, NOT to make a violin. But to understand what to do to make an emulsion ground, why it works, and how to modify it. In a word, how to understand it. Also, by the way, I enjoyed reading that upper layers also have minerals. I have always done this and there is a VERY good reason to do it. I may say later. I don't want to give a method for a science-ignorant craftsman to make fiddles. I make fiddles myself. The other day, one of your number offered to help set up a group where I could teach and demonstrate making these varnishes. He told me that Gary Bease had one and charged $2500 a head. I read Bease's book. It had nothing that was not available to him in old literature. But he made money on it. Should I charge for such a group meeting? Why do you expect to be given a method for nothing? I am not saying you would like my varnish at all. Or my violins' tone. I AM saying that the method is versatile. If you have a method, you won't have verstility. If you understand it, you can try many things quickly. Whatever you don't like about what I do, you can try to modify it more to your tastes. But only if you understand it.
Mauricio Posted January 25, 2009 Report Posted January 25, 2009 If two or three others read it and reply, I will give the next link. I read it and understood nothing, do I count? FWIW, I have tried the emulsion type of Imprimatura from Magister, but found the look (even after drying) a little milky. Paired with the fact that the sound of that particular violin deteriorated a lot from "in-the-white" to fully varnished, it made me go back to Magister's older version of Imprimatura. I confess I did not test that violin with only the primer on, so take my suspicion with a grain of salt (0.2 to 2 microns in size)
Johnmasters Posted January 25, 2009 Report Posted January 25, 2009 If you look about 3 pages down on ths document you will see a typical scanning electron micrograph of a gesso ground.Notice the scale at the top which is 200 microns.The top layer is fine gesso, the lower layer is courser.The micrograph of the Stradivari ground particles are extremely small compared to it.The lower layer is anhydrous calcium sulphate probably in a glue binder ,the upper layer is pure gypsum.Ucellos Battle of Romano Upon drying, some emulsions may push finer particles to the surface. There is movement and the evaporation of two volatiles. What goes on here? The particles definitely move around, and by 'particles' I include oil droplets. Is it really Gypsum or calcium sulfate? Are they the same? That is why I asked if there was x-ray diffraction data to distinguish between amorphous metal salts vs actual crystaline minerals.
GlennYorkPA Posted January 25, 2009 Author Report Posted January 25, 2009 Glenn, research ive seen on Venetian paintings from the same era or before says that they often contain uniformly shaped glass particles of very narrow size range.Usually around 3 to 5 microns.There was no explaination how they produced these particles though. Bob, There is a reference to glass powder being used in Venetian paintings as far back as the 14thC. This is possibly linked to the glassmaking industry in Venice at this time which sourced high purity quartz from the Ticino river which runs into the Po near Cremona. Itried looking at Johnmaster's wikipedia link but couldn't see anything relevant under HLB. Do we have to follow clues like a goose chase? Glenn
MANFIO Posted January 25, 2009 Report Posted January 25, 2009 Mauricio, I haven't read it, but I think I would not understand nothing also, as usual when I read these articles, but I may be too dumb. Anyway, after giving a look on the link provided by Melving with pics of the author's instruments I think I'll keep my current ground...
Johnmasters Posted January 25, 2009 Report Posted January 25, 2009 I read it and understood nothing, do I count? FWIW, I have tried the emulsion type of Imprimatura from Magister, but found the look (even after drying) a little milky. Paired with the fact that the sound of that particular violin deteriorated a lot from "in-the-white" to fully varnished, it made me go back to Magister's older version of Imprimatura. I confess I did not test that violin with only the primer on, so take my suspicion with a grain of salt (0.2 to 2 microns in size) Your sure do. I would like others to at least look at it.... droplets in one phase need electrical charges on the surface to disperse in the other phase well. Some mechanical action will help, but it is not the best thing. (glue-varnish emulsions are crude mechanical dispersions, Oded.) Milky is understandable. There are all kinds of emulsions. I have gotten it too in the past, but changed things to get rid of it. About understanding.... how does soap help wash your hands? The kids in grade school are told that one end of the soap molecule disolves in the oils on your hands. The other end is water-soluable. This causes the oils to break into tiny droplets and these are washed off as an O/W emulsion. (Although quite dilute) The kids know it.
Johnmasters Posted January 25, 2009 Report Posted January 25, 2009 Bob,There is a reference to glass powder being used in Venetian paintings as far back as the 14thC. This is possibly linked to the glassmaking industry in Venice at this time which sourced high purity quartz from the Ticino river which runs into the Po near Cremona. Itried looking at Johnmaster's wikipedia link but couldn't see anything relevant under HLB. Do we have to follow clues like a goose chase? Glenn Yes you do. Please read about washing your hands above. If you do, you will see how HLB is important. Or at least HLB is a way of classifying surfactants. You need a surfactant. What are you chasing after???
upnorth Posted January 25, 2009 Report Posted January 25, 2009 ...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 after exposure. Particularly if they are chrystalline silica. I don't think there is any evidence that dead violinmakers have anything to say about this except they did live long lives and made violins with an interesting ground applied to the wood. At least this is my impression from some preliminary research that I have done. Violinmakers live almost as long as Popes, I think. So either the exposure level was low to the powders either by special precautions, or they did not deal with powders since they were in solution or it simply was not enough to cause silicosis they seemed to have avoided occupational hazards of varnishing and wood dust. Or they simply were able to avoid the more hazardous substances that contained silica. For example, plaster of paris and pumice are safe while tripoli powder and diatomacious earth each contain silica in small amounts.
MANFIO Posted January 25, 2009 Report Posted January 25, 2009 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.
fiddlecollector Posted January 25, 2009 Report Posted January 25, 2009 Upon drying, some emulsions may push finer particles to the surface. There is movement and the evaporation of two volatiles. What goes on here? The particles definitely move around, and by 'particles' I include oil droplets.Is it really Gypsum or calcium sulfate? Are they the same? That is why I asked if there was x-ray diffraction data to distinguish between amorphous metal salts vs actual crystaline minerals. John ,if you go near the top of the page ,they used XRD .calcium sulphate and gypsum are the same ,gypsum is just the mineral form.I think the article means that The top layer is just gypsum without binder.It is a Tempera panel painting.
Mike_Danielson Posted January 25, 2009 Report Posted January 25, 2009 First, I want to clarify the recipe of Harris, Sheldon and Johnston since it was not correctly stated, earlier: 5 ml of a cooked varnish (40 g linseed oil and 30 g rosin cooked to firm pull with 15 ml turpentine added at cooldown) is ground with 1.7 g kaolin clay (china clay). A separate glue solution is made of 6 g dry rabbit glue to 30 ml of water. For 5 ml of varnish, about 30 drops of glue solution is added. After mixing the emulsion, an additional approximately 10 drops of water is added. The authors estimate that the DRIED film is 24.7% china clay and 2.6% glue by weight. Now, I went to the website of Harris and Sheldon and looked at their instruments--in my opinion, the ground is very transparent. They imply that this emulsion ground has been used for a long time (years) by them. In reading between the lines and going back to earlier postings on emulsions varnishes, I think John Masters would like us to use a casein-based surfactant at very small concentrations to help the oil wet the particulates. As a caution, Meyers in his book says that casein should never be used in oil mixtures (here Meyers is talking about oil emulsion gesso grounds), but no mention is made by Meyers of how much casein can be safely used. I can understand the frustration with how the world works--personally, I have given up on fixing it. I agree that the best lessons are those learned by doing some homework. Mike D
Johnmasters Posted January 25, 2009 Report Posted January 25, 2009 John ,if you go near the top of the page ,they used XRD .calcium sulphate and gypsum are the same ,gypsum is just the mineral form.I think the article means that The top layer is just gypsum without binder.It is a Tempera panel painting. Yes, different form... That is what I meant. If they are true crystals of gypsum ground up, that is one thing. If it is calcium sulphate, that is another thing altogether. (Again, that is exactly why I asked about x-ray diffraction.) The chemical composition is less important than having small mineral particles. The chemical composition may only be important as it relates to the index of refraction. And even the RI may depend on the form, crystal or amorphous. Now we are getting somewhere. Calcium sulphate and gypsum are not the same thing. I did not need to go to the top of any page. I looked up "gypsum" in Wikipedia and I see the problem here.
Janito Posted January 25, 2009 Report Posted January 25, 2009 Given the level of interest in this and other recent threads, I would like to suggest that those who have photographic examples of their experimental results post them to the Gallery This should create a useful comparative record.
Johnmasters Posted January 25, 2009 Report Posted January 25, 2009 In reading between the lines and going back to earlier postings on emulsions varnishes, I think John Masters would like us to use a casein-based surfactant at very small concentrations to help the oil wet the particulates. As a caution, Meyers in his book says that casein should never be used in oil mixtures (here Meyers is talking about oil emulsion gesso grounds), but no mention is made by Meyers of how much casein can be safely used. Casein is not a surfactant... You will get wetted particles with the glue-oil situation also. That is not the point. I don't know why Meyers says this. I read Meyers book early on in these experiments. Likely he is worried that casein is too brittle. That is the only objection to casein I have read. (For use on canvas, that is) Meyers must envision much larger portions of casein.
Johnmasters Posted January 25, 2009 Report Posted January 25, 2009 Given the level of interest in this and other recent threads, I would like to suggest that those who have photographic examples of their experimental results post them to the GalleryThis should create a useful comparative record. When I get my string of 6 violins polished up, I plan to send photos. You may not like them. But you can't see the ground either.
JimMurphy Posted January 25, 2009 Report Posted January 25, 2009 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
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