For years I have preferred to not sell my varnish because making it was and still is one of the most unpleasant experiences possible. The stench from the cooking varnish can only be compared to a combination of burning rubber, skunk, and raccoon feces. Though many of my readers will not be familiar with some of these odors, I can faithfully report that the smell, to which one is exposed from between 8-12 hours at a stretch depending on how much varnish you make in a single batch,is totally obnoxious. It is only during the last 30 mins that the smell changes to one that is quite pleasant. But that is no consolation to make up for that acrid terrible smell that permeates your nose, clothing, hair, and skin during the previous hours required to make the stuff.
Indeed, years ago I tried and was successful in convincing Georg Kremer of Kremer Pigmente in Germany to manufacture my varnish for me. I went to Aichstetten to show him and his varnish maker how to make my varnish. For a while they were making my varnish and selling it. But it did not take long for the varnish maker to threaten to quit if he had to make any more of my varnish...at least that is the story Georg told me about why he would no longer sell my varnish. Knowing how stinky my varnish is to make, I understood completely.
Faced with having to make this varnish myself, there was no way I would ever sell it to others...no amount of money was worth having to put up with the unpleasantness of making the varnish.
Well, now I have found someone who doesn't mind making the varnish and he wants to earn part of his income from making it. For this reason only, I am willing to sell my varnish to those who do not wish to endure the stench from cooking the varnish for hours on end until it is ready.
The price for my varnish is roughly competitive with the prices for small batch made violin varnishes that are already available on line at various different sites. I am offering my varnish for the following prices in the following amounts:
$135.00 for 30ml
$202.50 for 45ml
$270.00 for 60ml
$315.00 for 70ml
I offer a light varnish and a darker version. Of these two varnishes, the lighter colored is that the making of which I have described here in my article on making Ash Varnish below. These varnishes under UV light fluoresce opaque whitish canary yellow for the light and greyish canary yellow for the dark. These are the colors of fluorescence descibed in every book that scientifically discusses the ancient Cremonese violin varnishes.
Anyone wishing to purchase my varnish is welcome to contact me by email at email@example.com. Please use the words "purchase varnish" in the subject window lest my spam detector misroute your email.
The conditions for purchasing my varnish are that all sales are final and that the cost of shipping the varnish is not included in the price. I assume that anyone using my varnish already knows how to varnish a violin and therefore does not need to be told how to do that.
As I have already indicated in my article on Ash Varnish, this is an acoustically superior varnish. It enhances the sound of whatever violin to which it is applied. By enhancement I mean it makes obvious whatever the sound of the violin already is. The varnish is not magical, it won't make an acoustically indifferently made violin into a Stradivari. Rather it emphasizes what sound is there in the violin already. It does not improve the sound by making a harsh sounding violin more beautiful. It makes the harshness of the sound more obviously harsh. If the sound of the violin is dull, it makes the sound more obviously dull. If the sound is beautiful, it makes the sound even more beautiful; that is its real purpose.
Marianne Ploger is perhaps the most important musical scientist in the world today. marianneploger.com As you will see when you click on the above link, she is also an ingenious inventor. When I was puzzling about how to dry my violin varnish in a manner that would not require me to regularly turn my violins to prevent them from overheating, drying out and cracking, Marianne instantly suggested this solution. Marianne's invention is ingenious because it allows me to dry up to 6 violins at the same time. It is extremely efficient because it sets up in 1 minute. In fact it takes longer to hang the instruments from this set up than it takes erect or take down the device.
This interesting video has absolutely nothing to do with my violin varnish but I wanted to post it just for the fun of it.
Recipe for making your own Hill Violin Varnish
by Keith Hill
Instructions for Making an Acoustically Proven Varnish Using only Five Ingredients: Linseed Oil, Rosin, Water, Wood Ashes (Yes, Wood Ashes), and Turpentine
This is a revised reprint of an article I wrote that was published in the American Lutherie, the quarterly journal of the Guild of American Luthiers, Number 37/ Spring 1994. For those of you who may not have access to this journal, I have provided it here for your convenience.
Like many of my fellow Luthiers, I have made numerous experiments in concocting varnishes for use on my violins. I owe a debt of gratitude to earlier experimenters whose work and publications contributed substantially to the outcome. Those whose work contributed materially to the production of my varnish are Ole Bull, members of the 19th Century London Hill Family, George Fry, Jacques Maroger, and Joseph Michelman.
Ole Bull, in his tiny book on the violin, confirmed my instinct that the quality of the great Italian fiddles stemmed from the way all the parts were proportioned and not from the varnish even though the varnish contributes something valuable. He put no stock at all in the magical mysterious marvelous aspects of varnish which many during that time (how little things have changed) were given to worshipping. The books by the Hill family on the makers Stradivarii and Guarnerii provided a meager supply of extremely useful descriptive adjectives for the sounding and playing properties of the instruments by those makers.
George Fry's book describes many varnishes of little real value because his varnishes work neither acoustically nor mechanically. He also discusses the varnishes of other experimenters. One is William Fulton's Oil of turpentine varnish. I use this "Oil of Turpentine" varnish as the basis of my colorants. Should you decide to do so as well, take to heart what he says as his accurate descriptions of what happens when such varnishes are put together show that they can be very dangerous.
Maroger, in his book Secret Formulas and Techniques of the Masters, provides a wealth of information concerning the behaviors of the components of varnishes known to exist in painting during the 17th and 18th centuries.
Joseph Michelman contributed the most because of his belief, which he expressed to me over the phone during my only conversation with him, that the components of ash were the components of the Italian fiddle varnishes. Everything he said made sense to me. Unfortunately, his varnishes don't work very well either mechanically, visually, or acoustically.
Others whose work contributed positively in a negative way presented points of view that accord with the "holy varnish" mentality so common among varnish enthusiasts. They positively presented their beliefs about what the magical ingredient had to be; this helped me reject their avenues of approach. Since this closed many possible paths, they helped speed me on my way.
What I have found will, I hope, be of some use to you in your search for the best possible varnish.
The foundation for my varnish recipe is one simple principle. The violin must be a great sounding violin before it is varnished. If it is not, the varnish will not make it so. The varnish is there to assist in preserving whatever sound the fiddle has, protecting the wood of the fiddle, and enhancing the sound of the fiddle by the effects of its mechanical properties. In other words, the quality of the overall result from the effect of a finished violin is roughly 90% due to the box and how all of its parts are proportioned and the remaining 10% is due to the varnish. When both are right, whatever quality remains wanting comes with playing-in of the fiddle. How good the fiddle sounds depends on these factors. When all factors are at optimum, the result is what we can hear in a Strad or del Jesu fiddle or their equivalent.
Standards for a Useful Varnish
My standards for varnish are, in part, a compendium of traits, characteristics, and properties that have been noted by the above authors. Some are my own. Anyone who is well read in the literature will recognize the sources of the various standards. Here are those standards:
A. It should be easy to make. Easy here is a relative term. I mean that one should not have to be a chemist to make it. That is, almost anyone should be able to throw it together with reasonable success.
B. The ingredients must have been and still be easily obtainable by anyone without significant effort. No unusual ingredients must be present. All the ingredients should yield, upon spectrographic analysis, a reading similar to the findings published by Michelman in his latest articles on Ash Varnishes.
C. The varnish has to exhibit the following optical properties: 1.) dichroism-changing color depending on the angle of sight, 2.) absolute transparency-no apparent loss of light when it enters the varnish and when it leaves the varnish, 3.) uniform refraction-no matter at what angle you view the fiddle the light must not be diminished, 4.) magnification of wood substructure-an effect from light being uniformly distributed within the varnish such that every detail of the wood becomes obvious to the eye, 5.) naturally deep color-one that comes from the depth of color of the various ingredients, 6.) radiant color-the effect of certain components in the varnish that make the color extremely vivid, 7.) extreme effect of depth, h.) significant darkening with age yet never becoming fully dark brown to black but always appearing golden in whatever hue it finally becomes.
D. The varnish has to have the following physical and mechanical properties: 1.) the film should be extremely thin, 2.) the film should be extremely even and without runs or sags, 3.) the film should adhere fast to the previous coat yet maintain the integrity of each individual coat-it may not "melt" or dissolve the previous coat to ensure solid adhesion, 4.) the varnish should be made of ingredients that yield the lightest possible film-the varnish should not weigh down the plates which need to vibrate freely, 5.) the film must be curable only in the sun, 6.) the film must allow itself to be worked into a very high polish easily without being ruined easily. 7.) the film must be a self healing, that is, film nicks and scratches should eventually disappear without any human assistance unless they are too large, 8.) the varnish film must be capable of shrinking in all directions equally as it dries and cures, 9.) the film must be able to "sink" significantly into the surface as it ages, 10.) the varnish should never crack or check, 11.) the film, when dry, should be soluble in alcohol but not in turpentine, 12.) the liquid varnish should improve with age-getting clearer and more luminescent the longer you keep it, 13.) it should never "spoil" on the shelf--it should have an indefinite life so long as the container has not been left open. It should never thicken further, nor should it film over in the container, nor should it cure in the container.
My violin varnish fulfills every criterion stated above. If you share these standards, this recipe will interest you.
Here are the materials you will need:
--A few pounds of the dirtiest, crudest, darkest, ordinary rosin available. This can be easily obtained from your local sporting goods store in "batter's bags". (Baseball batters use the dust from this rosin to give themselves a better grip on the bat. The advantage of this rosin is that it is unrefined) High quality pure rosin can also be obtained for a better price from The Rosin Box, a store catering to the needs of ballet dancers in Philadelphia, PA. The purpose behind all the dirt and crudity of this rosin is twofold. One, the rosin is likely to be free of the acids used in the process of chemically cleaning rosin used to make commercially manufactured varnishes and paints. They remove all the "impurities" from the rosin so that it will never darken--this is a government imposed standard. By removing all the impurities, most of the minerals that give the rosin its color are also removed. Two, ironically, it is those minerals that give the great varnish much of its allure and charm. In fact, using ash to make the varnish is the method employed to "fix" even more of these impurities into the varnish than what the rosin or the linseed oil themselves can supply. No matter how dirty or crude rosin gets, it always maintains perfect transparency, i.e., it never is cloudy or milky. Of the material you get, use only the largest pieces in order to avoid using too much oxidized rosin in your varnish. You want your rosin to oxidize on your violin so that it cures properly in the presence of the other constituents.
--A few quarts of extra virgin cold pressed linseed oil. You can get this as salad oil in your local health food store. If you buy something that you can eat, you can be pretty certain no one has put chemical additives in it to make it dry better. You do not want hot pressed oil because, although it may have more "goodies" in it from the impurities standpoint, you can't be certain that the oil was really hot pressed and only hot pressed. Usually, the process for getting the most oil out of the linseeds involves adding chemicals to leach every last drop that can be had. These chemicals are harsh and will cause the varnish to deteriorate. It is for this reason that I do not even trust Artist quality linseed oil that can be purchased from the art supply shops. I suspect it to be chemically cleaned to make it clear. The salad oil linseed product is the finest. You can also buy a slightly less refined product in bulk from Kremer Pigment in New York or in Germany.
--A gallon or two of true Pure Gum Spirits of Turpentine. Nothing else will do. Not Spirits of Turpentine. Not Turps. Not Turpentine. And, even if it says on the can that it is pure gum spirits of turpentine, don't believe it. Smell the stuff. If it doesn't smell exactly like pine sap, don't use it--it probably has some petroleum additives to increase its bulk. And even if the store keeper says that nothing is added, trust only your nose. If it don't smell like pine sap, it probably isn't You can use the high quality PGST from the artist's supply shops but that can be very expensive. If all else fails, use that.
--One old large cooking pot that you will discard after use.
--One quart of reduced and processed Oil of Turpentine. This stuff takes about 6 months to a year to make.
Making the Colorant
I will recount for you my realization of Fry's directions for William Fulton's Oil of Turpentine varnish. That is so you don't have to go out and hunt for their books to make your own colorant. Then I will proceed with the directions for my varnish recipe.
Collect one gallon of pure spirits of turpentine, some ready to rust iron filings ( you can also use a bunch of steel pot scrubbers or very coarse steel wool), and an air pump with a length of plastic tubing used for fish tanks. Put the turpentine and the steel wool in a large gallon bottle (you can scrounge one of these up from a local restaurant--they buy their pickle slices in such jars). Set up the air pump to aerate the turpentine. Let it run for 6 to 12 months in a window, if you don't mind the smell, or on a porch, if you do. And make sure that you keep it covered to prevent it from acquiring dirt or water from rain. I put mine out in the garage.
When it is a little thinner than the flowing consistency of honey, it is ready for processing. Fry warns you in his book that this stuff when it is being heated is really dangerous unless you take adequate precautions. Here is why. This Oil of Turpentine no longer has the properties of turpentine. It isn't even soluble in turpentine anymore at this point. When you heat this material up, as soon as it gets to a certain temperature, it begins to cook itself. This is the dangerous part. Even if you removed it from the heat, it would continue to increase in temperature and cook as the volatile gases escape from the center of the mass. When this happens, it more that quintuples in volume as it bubbles up. Unless you take the precaution of having a pot that is more than six or seven times the size of the amount you are cooking, this material will spill over onto your heat source and explode covering everything, including you, in 400-500 degree impossible to remove scalding pitch which when it cools turns almost glass hard. This stuff is not fun.
The way to handle it is to watch the pot intensively while it is cooking. As soon as you notice the bubbling up behavior beginning, quickly put the pot on the ground and stand back. If it overflows, nothing will be the worse, and you can easily clean it off the ground. As soon as the bubbling up behavior subsides, it will never happen again. You can continue to cook this material for as long as you like. The longer you cook it the darker it become. I cook it until it is almost black. Its actual color when spread out thinly on a white tile or some other nonflammable white surface will give an idea of how dark you will want it. Remember, this is just a coloring additive and will be extremely diluted when in use. This is why I cook it to almost black. Thinned out, it turns a deep rich reddish brown. Mixed with varnish, it gives a blush of red brown that darkens significantly with age because of the iron dissolved in it.
Your oil of turpentine no longer exists at this point. What you have is a molten resin that can only be thinned in alcohol, lacquer thinner, and a bunch of other thinners you would never think of using in a high quality varnish, but not in turpentine. The only way I could discover to put this material, which is basically just a colorant (and a very transparent one at that) into an oil, rosin, and turpentine based varnish is to use Oil of lavender or Spike Oil of Lavender as a thinner. Oil of lavender has the unusual characteristic of being able to dissolve resins that are normally only soluble by either turpentine or alcohol. By dissolving this resin in alcohol, you would never get it to incorporate into your varnish. But with oil of lavender, it will incorporate effortlessly and it will smell glorious besides. I love the smell of my varnish for this reason.
At this point you are faced with a significant problem. How do you get this Oil of lavender, which is at room temperature, into your 400 degree molten resin and avoid an explosion? The difficulty you face is that the cooler the resin becomes, the thicker and more insoluble it becomes: at room temperature, it is like glass. You could pour it out on a slab of stone or a plate of steel, chip it off and crush it up into a powder and then reheat it with the oil of lavender until it dissolves. Or you do what I selected to do, that is, heat up the oil of lavender until it is hot enough to scorch a boar bristle brush hair causing it to curl and retreat. Meanwhile, your hot resin is cooling down slowly as your Oil of Lavender is heating up. The idea is to get both substances cool enough to avoid an explosion and hot enough to still mix relatively easily. Do this by testing the hot resin with hairs from a large natural bristle paint brush and doing the same test on the hot oil of lavender. When the behaviors are somewhat similar, you can try adding just a tiny amount of the hot oil of lavender to the molten resin. If a drop of the hot oil "steams" off in a rush of sudden evaporation, let your molten resin get much cooler. To add more will cause an explosion. When the two substances are within about 50 degrees of each other in temperature, they should be safely mixable. Slowly continue adding more oil of lavender (letting it cool) until you are using it at room temperature. At this point, the resin should be thinned enough to allow further thinning once it has cooled down to room temperature. Once at room temperature your thinned resin will be about the same in volume as before you began. But at this point most of that volume will be oil of lavender. In other words, one gallon of spirits of turpentine will yield about on quart of Oil of turpentine. And that quart of turpentine oil will yield about one cup of turpentine resin. When thinned back up to brushable consistency with oil of lavender, you have a bit less than a quart of sweet smelling very dark colorant for your varnish.
Directions for making Violin Varnish
Collect a pile of wood shavings, chips and scraps made up of pine and maple from off the workshop floor. Burn this until you have a heap of ashes. While the ashes are still hot, dump them in water. Old recipes for making soap tell you what the density of the resulting lye solution should be. It doesn't matter all that much what your proportions are except if there is too much water, you will spend a lot of time watching your excess water boil off. If you have too little, you will have a tough time getting your initial "soap" to be clean or free of ash.
Hot ash in water turns the metallic oxides in the ash into metal hydroxides (lye). A little lye goes a very long way so start with no more than a liter of lye water. Since these metallic oxides combine readily with water, they also use moisture in the air to do the job. Hence cold ash is less effective. Fresh hot ash will make the best lye for your purposes.
Once you have your hot ash lye, you are ready to make varnish. The more dense your lye solution, the more linseed oil and rosin you will need to use it up. It is best to plan to work with about a liquid gallon of varnish. This will require about a gallon or two of water and a shovel full of hot ashes. Bring your hot ashes to a boil and put the equivalent of three quarts of crushed rosin chunks into the hot lye. Continue heating this until all the rosin is melted and dissolved in the hot lye. This slurry will turn milky or cloudy as the lye emulsifies the rosin.
When you can no longer find any unmelted rosin and the mess in your pot looks uniformly milky, start to add your linseed oil until you have used up two quarts. This will give you a 2:3 proportion of linseed oil to rosin. If the slurry is still milky, continue adding first rosin, then linseed oil in a 3 parts rosin to 2 parts oil ratio until it begins to clarify. When it starts to clarify, that is, the milkiness begins to disappear, you have a neutral solution. If you want soap, you should leave it slightly cloudy. If you want varnish, you want it to be non cloudy. Do this by adding a bit more each of rosin and linseed oil taking care to maintain the 2:3 ratio of oil to rosin. Be aware that "cloudy" in the sense I am using it is relative--the slurry looks like gray muddy slop. Never fear, you can easily notice the milky or cloudy cast and you will notice when that cloudy or milky cast disappears.
What happens if your proportions are not correct? Nothing hideous. If you get too much rosin in the batch, the sound will be a bit brighter at the beginning but will also have a tendency to crackle and crumble. If you get too much linseed oil in the varnish, it will sound more dull at the beginning and become brighter as the oil dries and hardens with age. But the varnish will hold fast to the surface and will be tough and almost impossible to chip. It will also take much longer to dry, be harder to "dust up" when sanding, be more resistant to solvents, and look less beautiful. Such a tall oil varnish is ideal for furniture but not for a violin. In my judgment, it is better to err just on the side of having too much oil than having too little. The best, of course, is to hit the right proportion and keep to it. Bear in mind, too, that the oil of turpentine resin you use as the colorant constitutes part of the rosin portion of the varnish.
Once you have gotten your slurry to a slightly acid side of neutral solution with your linseed oil(linolic acid) and rosin(abetic acid), take it off the heat and let it stand over night. If you wish, you can let it stand for a week or two. The longer you let it stand, the more clear it will become as the ash settles out from the solution. I am much too impatient. After 24 hours, I like to get on with the job.
I should mention here, before going on, what you should do in case you reach a neutral solution too early. This will happen only when you have too little ash lye to begin with. It is a good idea to cook this part of the varnish on a wood burning stove so that you can scoop out some fresh hot ash and dump it into your varnish in the event you reach a neutral solution before having used up your ingredients in their respective proportions.
Next, take your settled-out solution and extract the water. The only way to do this is to boil it off. This may take a few hours depending on how much solution you have. Though water boils at 212 degrees, varnish does not, and once your water has boiled off, varnish is what you have. The trick at this point is to get your varnish to the correct temperature and hold it there until the oil and rosin have perfectly combined. The old method for telling the correct temperature was "hot enough to scorch a feather". Use this method for determining how hot to get it. Maintain the varnish at that temperature until it passes the "ball" test. Since it is possible to burn the varnish on the bottom of the pot, stir the varnish slowly and constantly using a glass rod or ceramic spoon (wood will burn at this temperature and metals conduct too much heat).
The Ball Test.
The ball test is used in making fudge. Fudge is ready when you put a drop of it into a glass of water and it forms a ball. When you handle this little ball, it should not be sticky. But that is for fudge. In making varnish, the ball test is passed when the little drop forms into a ball which, when you place it between your thumb tip and index finger tip and press can be made to adhere to both finger ends. And, and here is the clincher, when you pull your fingers apart you can produce a "gossamer thread". Before the varnish is perfect it will form a ball, it will stick to your fingers, but it will not produce that gossamer thread. As soon as the varnish has reached the balling stage, you need to be constant and alert for that moment at which the varnish comes to perfection--to that gossamer thread moment. When that happens the spider-silk like thread that is produced is a product of great beauty as it maintains its integrity no matter how far apart you draw your fingers. It is golden and silvery in appearance. It is extremely fine and flexible. It is exquisite.
As soon as this moment has been reached, remove the varnish from the heat. This is extremely important. If you continue to heat this substance it will magically change from varnish into linoleum .
--Thinning the hot varnish.
I immediately begin to heat up my pure spirits of gum turpentine until it begins to look like it will boil. At the same time, I put the varnish in its pot into a tub of cold water. Herein lies a problem. The varnish, which is easily stirred when it is over 300 degrees gets gradually more and more viscous as it cools. At room temperature, this material (unthinned) would set up just like soft fudge. What you need to do is to get enough hot turpentine incorporated into the varnish before it cools down so much that you can no longer thin it because the viscosity prevents mixing. This is a tricky affair. You can not reheat the varnish without destroying it so you have only one opportunity to get the turpentine incorporated. So as soon as you think you can safely incorporate the two do so. Here a candy thermometer is useful. When the two substances are within 50 -75 degrees of each other in temperature, they can be mixed reasonably safely. The danger is in having the hot turpentine explode into flame when it is ignited by the super hot molten varnish. You must plan to have at least half a gallon of hot turpentine ready for the initial thinning and another gallon and a half of cold turpentine on hand to complete it. Your varnish is safely thinned when the container is cool enough that you can tolerate touching it for a moment with you bare hand and still thin enough to be brushable. When cooled, this varnish, which has the viscosity of honey, will still need considerable thinning to be easily brushable. I prefer to get the varnish to an easily brushable state while it is still hot. As soon as I have thinned it to that point, I stop and let it cool.
Once it has cooled, you will need to thin it until it has the brushing viscosity that most pleases you. Too thin and you will have to apply many coats to build up any substance to the film. Too thick and it will be hard to move around on the surface. Here are a few characteristics of this varnish that you should know about for you to ascertain how thin you wish to make it. No matter how thin this varnish gets, the handling property of the varnish is that of soft butter. It stays where you put it without running, dripping, or sagging. This effect comes from the presence of Calcium, in the varnish, that is a principal component of ash. The calcium also imparts uniform light refraction into the film. Bearing this in mind, I prefer to keep my varnish about the same viscosity as oil paint fresh out of the can. At this viscosity, it is very easily brushed and it requires only three coats to finish a fiddle. The first to soak into the surface to seal the surface. The second to create a uniform coat. The third and sometimes the fourth to add resilience to the surface by stiffening it.
The body which this varnish has comes from all of the metals that have been incorporated into the varnish. Yet for all the incredible body of the fluid state of the varnish, once dry it forms an extremely thin film because it shrinks on to the surface as it dries. This shrinking behavior is extremely important for the preservation of the acoustics of the fiddle. Varnish which does not shrink on to the surface but simply lays there as most varnishes do actually dampen the acoustics of the fiddle. By shrinking, the varnish envelopes the violin in tight embrace becoming one with the fiddle. In this way, it responds as the wood responds to the energy from the strings yet controls any wild vibrations that might occur in the plates.
This shrinking behavior that is peculiar to this varnish accounts for much of the quality that varnish should add to the sound. The more the varnish shrinks, the stiffer the outside of the surface of the instrument becomes. As the varnish shrinks and hardens it creates a "case hardening" effect on the instrument. When the instrument is set out in the sun to cure this varnish, the sun desiccates the wood, thus shrinking the wood, and makes the varnish, which has already been shrinking, even tighter in its clutch around the instrument. As the wood expands again as it takes in moisture from the air at room temperature, the tightening increases even more. The term, case hardening, is a term coined when the process used to make modern steel music wire was invented. By making wire that was extremely hard, that is, having the molecules more densely packed, on the outer surface while being softer and more ductile in the center, wire makers were able to fabricate wire that was both brilliant sounding and fundamental. And the wire was very hard to break because the inner softer core allowed the material to flex easily. This same process was used in ancient Japanese sword making to create swords that would hold an edge and yet be ductile enough to not break during use. The ductility prevents the brittleness that comes from hardness. Likewise, the varnish creates a compact outer surface that extremely tightly surrounds a softer wood inner core. This effect contains the sound energy in the instrument causing the sound to ring. And, very importantly, it does this without adding significant weight to the whole or without sacrificing flexibility. These two factors would otherwise dampen the vibration of the instrument.
The metal salts that are dissolved in the water that is absorbed by the trees that eventually become part of the solid material of the wood that turns into violins as well as wood scraps that get burned in the stove that turn into ash that becomes the basis for this varnish all have a significant role in imparting to the varnish highly desirable properties. Calcium also helps this varnish to adhere fast to the surface and to darken significantly. (Calcium from quicklime was also the basis for waterproof cheese based glue used in furniture and instrument making in earlier times. The German word for glue is still lyme.) Aluminum gives this varnish its extreme adhesiveness and toughness so that when it shrinks on to the surface, it does so uniformly. (Aluminum, when combined with proteins (amino acids), causes coagulation. I suspect that in the varnish it causes bonding of the several coats and acts like a linking mechanism to connect the oil and rosin (acids also) molecules together giving it a chained behavior.) Zinc gives the varnish its flexibility and self healing properties. (Zinc is the mineral we take as a supplement because it is responsible for tissue integrity) Manganese lets the varnish turn hard. Iron makes the varnish oxidize evenly and contributes to the gradual darkening as the varnish ages. These minerals all do these jobs to exactly the right degree when they are proportioned as they are in wood ash.
Also because of the body, this varnish covers the instrument and seals completely in just three coats of the viscosity I recommend. In this regard it is like shellac. Its drawbacks relative to shellac are mostly the time required and the conditions required to dry and cure it. It takes a week--minimum-- to dry each coat properly. And it must spend at least three days in the sun to properly cure the varnish.
Once you have thinned your varnish to a brush ability you like, try brushing it on a clean prepared surface. If the varnish has a tendency to froth like a soap, you definitely need to incorporate some of your oil of turpentine-oil of lavender colorant. This will help speed drying, it will make the varnish slightly darker per coat, and it will make the varnish acid enough to prevent frothing. If your varnish does not froth, so much the better. This brings me to the question about color.
I showed one of my fiddles to a well known major concert violinist about 12 years ago. He played it and complemented it highly for its tone. When he finally stopped playing, he asked me why I did not distress the finish of my fiddles as most other makers do and why my varnish was so blond? My answer to him was a question. That was, Had he ever in his life seen any paintings made in the 17th or 18th centuries that showed a violin or cello that was either distressed or brown? No, he had not. Neither have I. If the varnish is right, which is my point of view, it should look like the varnish as seen in the iconographic record. To tamper with the varnish by distressing it and using coloring additives, all designed to give violinists of today the delusion of playing on an antique, will result in a product that ten year hence looks stupid and fake. His answer to that was that I would not be able to sell my instruments because no violinists would buy them. In this he was and is absolutely right.
My intuition about the aging properties of this varnish have proven themselves by now. Instruments that I made 13 years ago, which were blond colored at the outset, are now a rich deep rosy golden blond-brown, absolutely transparent, and still possess a trace of fragrance from the oil of lavender. Now, they look like well preserved antique fiddles though still not as deeply brown. That deeply brown color has still to come from the oxidation of the wood from within the varnish. As the oxidation process reaches from inside the violin gradually to the outside of the fiddle, the color will begin to change again and its color will be complete. This may take 100 years, but I know it will happen. Instruments which have been artificially colored to look instantly antique today will look pasty and decrepit in 100 years.
Perhaps the greatest beauty of this varnish is its paradoxical origins. A coating of such beauty fashioned out of that dirty, muddy, ashened slurry assumes a more wonderful awe in me than if it were to come from the purest most refined products. Add to this the fact that this varnish never skins over in the jar, and that it fulfills every standard by which antique instrument varnishes are to be judged save the color (when new), it is no wonder that instrument makers have been puzzling over how this varnish came to be in the first place and that they attributed all of the acoustical qualities of the old violins to what appeared to their eyes to be self evident--how could their eyes be lying when what they heard was glorious?