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TECHNICAL INFORMATION



Modernized Violin Varnishes - By Joseph Michelman

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In my researches on the rediscovery of the old Italian violin varnish, it was essential to use only materials that were available during the years 1550 to 1750 when Stradivari, the Amati, the Guarnerei, etc. produced their masterpieces. For example, clay, wood ashes and madder root were the primitive sources for some of their raw materials. (1) But such sources are not satisfactory in modern times. One violin maker wrote that he tried to prepare an extract from clay and placed it to dry on the roof of his house. He reported his results in this manner: “And then the rains came.”

It may be helpful to summarize the progress and the improvements that have been made after eleven years further research since my book was published and to describe modern adaptions so that violin makers can use them more readily. The scientific and chemical background should be explained. For the sake of brevity, it will be necessary in the following formulas and discussions to refer to portions of my book. (2)

The original principles concerning the composition and the preparation of the varnishes remain valid and have been confirmed by analyses of old Italian varnishes. (3,4,5) Linseed oil and the metal rosinates remain as the fundamental ingredients; however, boiled oil is now preferred because of its better wearing quality and because clear films are obtainable with the resins to be described in this article. (See pages 56 and 57). The oil may be boiled over a small amount of umber in which case ageing for clarification is necessary. The ratio of oil to resin remains three to two.

Some changes have been made in the preparation of the metal rosinates which impart improved properties to the varnishes.

(1) Preparation of Rosin Solution.
275 cc’s Water (distilled preferred).
13.8 grams Potassium Carbonate (c.p. K2CO3)
30.2 grams Gum Rosin (ww grade)
300 cc’s Cold Water for chilling

DIRECTIONS:
Dissolve the potassium carbonate and the rosin in 300 cc of water by boiling in a liter Pyrex beaker. This requires a few minutes depending on the size of the lumps of rosin which should be clear, pea to nut size. Boil for five minutes more. Add 300 cc of chill water and make to 600 cc final volume.

DISCUSSION:
The substitution of potassium carbonate for potassium hydroxide (Preparation 1, page 38) may not appear important at first glance. Potassium rosinate is formed in both instances. Moreover, the foregoing formula is very similar to Preparation 8 on page 49; it differs only in the amount of potassium carbonate; this gives the incidental advantage that the time for the rosin to dissolve is greatly shortened. The explanation for the change can be understood from the chemical reaction:

K2CO3       plus     Rosin
    138                     302
                    gives
KHCO3 (Potassium Bicarbonate) plus Potassium Rosinate

The formulation of the potassium bicarbonate is important in the precipitation of the resins which will be explained later.

(2) Preparation of Precipitants.
100 cc 5% Aluminum Chloride Solution (AICI3 H2O)
30 cc 5% Calcium Chloride Solution (CaCl2)

DIRECTIONS:
Five percent solutions are prepared by adding 5.0 grams of each salt separately to each 100 cc water. The foregoing mixture contains nearly equal amounts of aluminum and calcium.

DISCUSSION:
Calcium chloride has been added to the precipitating solution because analyses of old Italian varnishes disclosed the prese4nce of calcium compounds, and further research has shown that their inclusion is desirable when used in conjunction with other metals; the use of calcium rosinate alone in the varnishes was not found satisfactory. (Preparation 31, page 84). The formation is of colored compounds from aluminum and calcium with alizarine is still not thoroughly understood (6) but the combination does yield lightfast colors.

Since calcium chloride is now present in the precipitant, alum, a sulfate, should not be used because of the formation of insoluble calcium sulfate upon standing. This is the only reason that alum, recommended in the book (pages 34, 39, 50 etc.) is now replaced by aluminum chloride.

(3) Precipitation of Resins.
100 cc’s potassium rosinate Solution (above)
60 cc’s Al-Ca Precipitant (above)

DIRECTIONS:
The two solutions are mixed whereupon a white precipitate is formed. This is treated according to Preparation 2, page 39. In fact, the precipitate contains a form of aluminum rosinate. The completeness of the reaction may be tested with blue litmus paper which should turn red.

DISCUSSION:
When the precipitant is added to the potassium rosinate solution, normal metal rosinates are NOT formed. (See page 50). Instead, it has been found that basic metal rosinates result, perhaps A1(OH)(rosin)2 because of the presence of potassium bicarbonate. This is desirable because the resins are harder and the varnishes in which they are used are less affected by moisture. After the book was published, reports were received that varnishes, made from rosin solution according to Preparation 1, page 38, became soft and tacky in hot humid weather. This defect is eliminated by these modified resins.

Some violin makers question the use of rosin varnishes. This discussion should explain that rosin does not appear as free rosin in the final varnish resins but is combined with metals. The undesirable properties of rosin (high acidity, for instance) have been removed. Aluminum, iron and calcium rosinates are different from unreacted rosin for varnish making purposes.

Alizarine will be used to color the orange and red varnishes and the amounts to be used have been indicated in my book; the two percent suspension is still used and is added to the potassium rosinate solution in which it dissolves readily. Iron compounds remain as the coloring agent for the brown varnishes and the amounts of iron salts to impart various shares of brown have been outlined. However, iron chloride (FeHl3 6H2O) should now be used because ferric alum is also a sulfate and should not be mixed with calcium chloride in water solution.

The working life of the resins may be extended by storing them in a tightly stoppered bottle in a refrigerator. Turpentine remains as a satisfactory solvent for the varnishes in the proportions suggested in the book; however, it has been found that a solvent called dipentene imparts better “brush ability” to the varnishes because of its slower evaporation rate.

The varnishes, together with the preliminary treatment of the wood with raw linseed oil, produce a finish for violins, violas and cellos that is surpassingly beautiful and worth the time and effort to prepare it. And the violin maker who does use it will have the deep, heartwarming satisfaction that the finish is one that the old Italian masters might well have used.

References

(1) Michelman, Joseph. “Scientific Monthly”, Vol. 81, No. 5, November 1955, pages 221-223.
(2) Michelman, Joseph. “Violin Varnishes”, Cincinnati, Ohio. (1946).
(3) Michelman, Joseph. “Journal of the Franklin Institute”, June 1949, page 569.
(4) Letters, Karl. “Farbe and Lack”, July 1952, page 293.
(5) Michelman, Joseph. “Science”, September 22, 1950, page 337.
(6) Ciba Review, No. 39, May 1941, Page 1418 and others.

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FORMULA 411
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“Formula 411” Varnish Recipe - By George Manno

Variations of the varnish receipe described below have been around for the last four hundred years. As I understand it, it started out being known as “Fioravanti’s Red” in Bologna, Italy around 1564, and was mainly used by artists. It wasn’t until the early 1700’s that this oil paste was diluted with turpentine and used for violin varnish. Since that time, ingredients have been added to, and then taken away from the original formula.
In 1904, George Fry’s book, Italian Violin Varnishes, referred to this receipe as “Formula No. 11.” In 1934, American violin maker David Coll suggested the use of Venetian Turpentine in place of Greek pitch to give the varnish a deeper red color. Some time later, the French added Sandarac to the recipe, while cutting back on the amount of Venetian Turpentine used.
Unlike “1704”, Formula 411 varnish can be used on new instruments. The color is a beautiful golden red. If there is one drawback to this varnish, it is the drying time. The instrument must hang in direct sunlight for four or five days between coats.

A word of caution: DO NOT MAKE THIS VARNISH IN THE WORKSHOP. THIS VARNISH MUST BE PREPARED OUTDOORS!


FORMULA 411 VIOLIN VARNISH RECIPE

Ingredients Needed:

74 ml.: Varnish Makers Linseed Oil (74 ml. = 2 ½ oz.)Hotplate
150 ml.: Venetian TurpentineGlass Stirring Rod
70 gm.: Gum Rosin (WW Grade)Timer
½ Liter: Gum Spirits of TurpentineGlass Jar w/Screw on Lid
Cast Iron Pot (2 Quart)

Mixing Instructions:

Mix 74 ml. Of the Linseed Oil and 70 grams of rosin in a two quart cast iron pot and place on the hotplate set on high; stir constantly with glass rod. As the oil and rosin are heated, the rosin will melt and begin to smoke, giving off a strong, pungent odor. When all the rosin has melted, set the timer for fifteen minutes and stir in 150 ml of Venetian Turpentine a little at a time. Continue stirring until the fifteen minutes has elapsed. Remove the pot from the hotplate and allow the varnish to cool for five to seven minutes. Dilute the varnish with the turpentine until you have the consistency for use with a brush. Stir for five minutes. Store in a glass jar with a screw on lid. The varnish is ready to use.

NOTE: This varnish has a shelf life of about one year. Should the varnish thicken, it can be thinned with a small amount of turpentine.

Reprinted with permission.

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1704 VIOLIN VARNISH RECIPE

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The recipe below is a well known varnish recipe. It makes a beautiful golden spirit varnish. It is especially good for touch up, as well as for new instruments.

Ingredients Needed:

45 gm. Seedlac
7.5 gm. Elemi
200 ml. Alcohol
9 ml. Spike Lavender Oil

Mixing Instructions:

Place all the ingredients in a glass container with a lid and let it dissolve. Stir or shake the mixture twice a day until the seedlac is dissolved. There will be insoluble material left on the bottom of the jar i.e. dirt, twigs, insect parts etc. This process may take several weeks. When completely dissolved, heat in a double boiler for several minutes. Let the mixture cool and the reheat again for several minutes.

USE CAUTION WHEN HEATING AS THE ALCOHOL IS VERY FLAMMABLE!

While the mixture is still warm, filter through a fine cloth to remove the insoluble materials. After the varnish is filtered and cooled it is ready for use. The varnish may be thinned with alcohol if it is too thick.
Store the varnish in an air tight container.

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FERROUS SULFATE

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Ferrous sulfate, also known as green vitriol, is available as a light green powder or crystal. A good stock solution can be made by dissolving two ounces in one quart of water. Small amounts of the stock solution when diluted with water will produce lighter shades.

Ferrous sulfate stains wood by reacting with the tannin present in the wood. It works best on woods that are high in tannin such as oak, walnut, mahogany and cherry. It works to a lesser extent on woods such as maple, birch, cedar and beech. It will produce silver-gray to steel blue colors depending on the strength of the solution and the species of wood. Prestaining woods that are low in tannin with a solution of tannic acid will produce results similar to woods that are naturally high in tannin.

Ferrous sulfate can also be used in conjunction with logwood extract to produce an ebony stain. To one pint of boiling water add one ounce of ferrous sulfate and ½ ounce of logwood extract. Apply this to the wood while it is hot. When the surface has dried thoroughly wet it with a solution composed of seven ounces of rusty nails dissolved in ¼ pint of vinegar.

You should experiment with the stain or dye on scrap wood until you obtain the desired results.

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POTASSIUM DICHROMATE

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Potassium dichromate is a reddish orange crystalline material. A good stock solution can be made by dissolving four ounces in one quart of water. Small amounts of this stock solution when diluted with water will produce lighter tones.

Potassium dichromate stains wood by reacting with the wood itself. Mahogany is one of the woods affected most strongly by potassium dichromate. When sponged with a solution the wood becomes a dark, rusty red and the contrast between the light and dark markings becomes more accentuated. The color produced depends in part on the type of mahogany used. On Cuban or Spanish mahogany the effect is more pronounced than on Honduras or Philippine Mahogany.

With potassium dichromate oak can be stained a dark rusty brown. Maple and birch are stained a soft yellow. Other colors can be achieved by applying a prestain before applying the potassium dichromate solution. Two prestains that can be tried are tannic acid and logwood extract.

Other effects can be achieved by adding potassium dichromate to a water soluble aniline dye and applying the resultant solution.

Generally, speaking, there isn’t a stain or dye that can be guaranteed to produce a certain color unless all the facts are known regarding the wood used. Even then the results are not certain. You should experiment with the stain or dye on scrap pieces until you achieve the color you are looking for.

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POTASSIUM PERMANGANATE

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Potassium Permanganate is a dark purplish-violet chemical that is readily soluble in water. One or two ounces dissolved in a quart of water will stain most hardwoods a pleasant brown. If the color is too dark it can be lightened by washing the wood down with a solution of sodium thiosulfate (also known as hypo). A solution of potassium permanganate loses its potency on standing so prepare a new solution each time.

A handsome lasting walnut color can be obtained by preparing a solution of six ounces of potassium permanganate and six ounces of magnesium sulfate (Epsom salts) in two quarts of water. The solution is applied hot to the wood with a brush and the application is repeated once.

Use caution when working with potassium permanganate as it is a strong oxidizer.

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BRAZILWOOD

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In 1500, when Pedro Álvares Cabral and his crew, having been blown off course en route to India, chanced upon an unfamiliar shore Cabral prudently claimed the land for the Portuguese Crown and ordered his crew to take on board examples of flora and fauna that showed commercial potential. Brazilwood, botanically known as Caesalpina echinata (often known simply as “brazil”) is a tropical hardwood of the family Leguminosae whose core yields a brilliant red pigment ideal for dyeing cloth. Brazilwood is a creamy color when first cut, but once it has been reduced to sawdust and soaked in water for several weeks, the dyestuff leeches into the solution and can be used to produce the fashionable red clothing particularly favored in the French court. Although the name is of uncertain origin, “brazil” is thought by some to be derived from brasa, the Portuguese word for a red-hot coal or from the Arabic word braza, meaning bright red. More likely the term was adopted from the common name for an East Indian dyewood called “bresel wood” which was first imported to Europe in the Middle Ages. Dyers of old used brazilwood as an additive to heighten the color of madder, or as a cheaper substitute for cochineal.

To extract the color from the wood 4 ounce wood chips should be placed in a cheesecloth bag or nylon stocking and let soak in 1 gallon of water for 1 week. After soaking , cover and bring the chips and water to a boil, and let them boil vigorously for 1 hour.

Brazilwood extract is used in a manner similar to logwood extract. When used with the following mordants it will give these colors; Potassium Dichromate, red to maroon; copper sulfate, pink to red; ferrous sulfate, gray to black; alum, crimson; and tin, pink. When vinegar is added to brazilwood extract the range of colors shifts to scarlet to rust colors and with baking soda the colors are shifted to the blue and magenta colors.

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DRAGON'S BLOOD

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A large number of substances, quite different from one another in composition and properties, and which have no common properties except their red color, have been erroneously classified as Dragon’s Blood. The true Dragon’s Blood is the product of the Calamus draco, a Malay palm allied to the rattan with a stem bristling with sharp spines. This climbing stem may rise to a considerable height. It is not cultivated, and only the trees growing wild in the forest are exploited. The resin exudes from the fruits. The C. Draco bears a great number of rounded fruits the size of a cherry, the surface of which is covered with smooth imbricated scales. The surface on maturity of the fruits are covered with a layer of friable red resin. The fruits are then collected, beaten in sacks to detach the resin, which is sifted to separate the fallen scales. It is beaten in boiling water and kneaded into ball's (Dragon’s Blood olives) or in long thin cylinder's (Dragon’s Blood in sticks). These are the most esteemed. The fruits that have been used in the preceding operation are crushed and boiled in water; the resin that they contain floats to the top. It is separated and made into cake's (Dragon’s Blood in cakes). The ligneous residue that has been boiled is kneaded into balls and sold as common or lumps Dragon’s Blood. Contrary to what one might believe, it still contains a comparatively high proportion of resin. Good Dragon’s Blood is dark red, opaque and friable. Its fracture is red and brilliant. Its odor and taste are scarcely appreciable. Its powder is red vermilion and slightly soils paper. It is insoluble in water and almost completely soluble in alcohol, benzene, chloroform and carbon disulfide.

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GAMBOGE

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This yellow gum resin is produced by several species of guttiferae of the genus Garcinia, a genus comprising numerous species of tropical evergreen trees. These species are Asiatic, being more particularly native to Indochina, Siam, India and Ceylon.

Indian gamboge is the gum resin secreted by the Garcinia Morella, an evergreen tree of the forests of the Kasia hills, Eastern Bengal, the West Coast and Ceylon. The gamboge of European commerce comes from Siam and is obtained from Garcinia Hanburyii. This tree grows not only in Siam but in Thailand and all Indochina. Gamboge has been known since ancient times. Clusius was the first European writer to mention it in 1605, Chinese books refers to it in the thirteenth century. The gum resin is not collected to any extent in India, that country receiving its main supply from Thailand. The trees are ten years old before spiral tapping, which is done during the rainy season, when sap is vigorous. The spiral is cut around the trunk 10 feet from the base. The resin trickles down into hollow bamboo's and when left for a month or so to solidify. The bamboo joints placed over a hot fire crack and a round stick of gamboge is obtained from each, the roll or pipe gamboge of commerce. The best samples of pipe gamboge are of a brilliant pale yellow when rubbed with the moistened finger. It is dense and brittle like glass. Its fracture is conchoidal, smooth, and shining, and of a reddish-yellow color, which soon changes to liver color, the surface becoming coated with a dark green layer. It is odorless. Its taste is slight at first, but it produces an aftertaste in the back part of the palate or throat that is unpleasantly acrid. The streak is lemon-yellow changing to orange. Its powder is a brilliant yellow, but it is less dark than the surface of the section. Mixed with water gamboge forms a beautiful yellow emulsion that is used in watercolor painting. It dissolves completely when treated successively with alcohol and ether.

Gamboge contains, according to the kind, 35 to 80 per cent of yellow resin and 14 to 19 per cent of gum soluble in water. The resin consists of gambogic acid and may be separated from the gum and impurities by dissolving in alcohol. By evaporating the alcohol pure gambogic acid is obtained as a deep brown-red color when pulverized becomes converted into a beautiful yellow.

Gamboge is very soluble in ether, less soluble in alcohol. It is often adulterated with starch, sand, and tinctorial barks, a fraud that is detected by dissolving the finely ground resin in 60% alcohol and examining the residue with a microscope. Gamboge as met with on the market varies greatly in quality. Gamboge from Ceylon, a pseudo-gamboge, is said to be very inferior.

Gamboge is used to color golden lacquers but, it is not very light fast. Moreover, it is poisonous, being a drastic purgative. Pigments have been made from gamboge by converting the resin acids into metallic gambogiates.

Gamboge can be used as a ground color on violins. There are two different theories though as to what should be used. Some say the materials that dissolve in alcohol should be used and others say that the residue that remains should be used. The solution can be prepared by placing the gamboge in alcohol and letting it sit for several days and shaking it each day to help it dissolve.

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LOGWOOD

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Logwood, also known as Campeche wood, is the heartwood of a South American tree (Haematoxylon Campechianum). It is a small many trunked tree that was named by the Spaniards who discovered it on the shores of the Bay of Campeche in Mexico. Logwood was introduced to Europe in the 16th century and was especially prized because it could produce a good black with an iron mordant. The dye is found in the heartwood of the tree. It is usually available as chips, powder or in extract form. It is used with various chemical mordants to stain wood various colors. Depending on the mordant used logwood will yield blacks, grays, violets and blues.

To use the extract dissolve one ounce in one quart of hot water. This will give you a dark red to purple solution. Applying this solution, while hot, to the wood with a sponge or brush is best although it can also be applied when cold. Let the wood dry for 24 hours. Now brush or sponge on a solution of one of the following mordants, depending on the color desired. For grays and blacks use ferrous sulfate, for blues use copper sulfate, for lavender use alum, for purple use tin chloride, and potassium dichromate generally gives a blue toned charcoal color. To develop the purple color using tin requires the use of Cream of Tartar. Mordant solutions are prepared by dissolving two ounces of mordant in a quart of water. After applying the mordant solution let the wood dry for 24 hours. If the color is not dark enough another coat of the mordant can be applied.

To prepare a good dye using either chips or powder, it must be soaked overnight and then boiled vigorously about 30 minutes. The liquid is strained out; this is the dye. More water can be added to the wood, as further boiling will extract more dye. In formulas calling for one ounce of extract use two ounces of chips or powder.

The following are some example formulas using logwood. Other information and formulas can be found in "Adventures in Woodfinishing" by George Frank and "Woodfinishing" by F.N. Vanderwalker.

  • Ebony Stain - To one pint of boiling water add ¾ ounce of ferrous sulfate and one ounce of logwood powder. Apply this to the wood hot. When the surface has dried thoroughly, wet it with a solution composed of seven ounces of steel filings dissolved in ¼ pint of vinegar.

  • Ebony Stain - In one quart of water boil ¼ pound of logwood powder, subsequently adding ½ ounce of potassium carbonate, after strainings apply the mixture hot. Then again boil the same quantity of logwood in the same quantity of water, adding ¼ ounce of copper sulfate and ¼ ounce of ferrous sulfate, after which strain and put in ¼ pound of rusty steel filings. With this latter mixture coat the work, and, should the wood not be sufficiently black, repeat the application.

  • Weathered Oak - Boil together 4 ounce of logwood powder and three ounces of ferrous sulfate in 2 quarts of water for 40 minutes and the solution applied hot. When this has dried it should be gone over with a wash made from 4 ounces of steel filings and 1 pint of vinegar. The steel filings are previously put into the vinegar and allowed to stand for several days. This will penetrate into the wood very deeply, and the stain will be permanent.

  • Rosewood - Boil ½ pound of logwood powder in 3 pints of water. Continue the boiling until the liquid assumes a very dark color, at which point add 1 ounce of potassium carbonate. When at the boiling point stain your wood with 2 to 3 coats, but not in quick succession, as the latest coat must be nearly dry before succeeding with the next. The use of a flat graining brush, deftly handled, will produce a very excellent imitation of dark rosewood.

  • Mahogany - Rub the wood with a solution of potassium carbonate, ¼ ounce to one quart of water, and then apply dye made by boiling together 4 ounces of madder root and 1 ounce of logwood powder in two quarts of water.

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MADDER ROOT

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Madder (Rubia tinctorum) is one of the oldest dyes known and its color fastness is among the best. It is such an excellent source of red that its name (rubia) means red in several languages. In Holland, during the 15th-17th centuries it was the principal source of wealth. By 1792, encouraged by Charlemagne, France was the top grower. We are told that the French Revolution ruined the farmers; they were later revived by a decree of Louis Phillipe that made red caps and trousers mandatory for his army. Likewise in England, imported madder was also used for their army uniforms (redcoats). When alizarin, or synthetic madder was synthesized in 1869. A world madder production of 70,000 tons yearly declined to nothing. In preparing the dye from the roots be sure not to use too much heat or boil it too long as the color may shift to a muddy brown.

To extract the color a good procedure is to soak the roots overnight in water. The soaking water should be discarded. Add fresh water and slowly bring to a simmer, about 185-190 degrees F. Let simmer for 1-2 hours. The colors that can be expected with various mordants are red with alum, garnet with chrome, orange/red with tin/alum, dull garnet with iron/chrome.

Synthetic alizarin is much easier to use and readily available and gives colors that are indistinguishable from madder root. For a detailed procedure for making the madder lake see the article by David Rubio at www.rubioviolins.com.

For a golden color from madder proceed as follows: Dissolve 2 grams of lye (sodium Hydroxide) in twenty ounces of water. Moisten 2 grams of alizarin, stir with a little water and then pour into the lye solution. Add to the alizarin a solution of 4 grams of tartaric acid dissolved in 15 cc of water. The precipitation is the yellow color.

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SEEDLAC

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Seedlac resin is produced by the lac insect Lachardia lacca, a tiny red insect, not larger than a small apple seed. Lac resin is excreted by the insect and deposited on the trees that it lives on. These trees are called host trees, the most important of which are kusum, ber, ghont, and palas, all of them native to India, Burma and Thailand.

The lac resin contains a red dye and the lac insect was originally cultivated as early as 80 AD for the production of this dye. The far more valuable resin was not recognized until the 16th century. It was recorded about 1590 AD that Akbar the Great, a Mogul emperor, used it mixed with pigment, in the preparation of varnishes. However, the lac dye remained the more important product until the 18th century when the value of the resin was recognized in Europe and methods of using it were perfected.

The collection of lac in India is scattered over a wide area. About two thirds of the crop is collected from an area lying between Calcutta and Central India. Smaller amounts are now collected in Burma, Thailand, Vietnam, Laos and Cambodia.

There is a very marked difference in the color of the lac from different areas. The lac from west of Calcutta is yellow or orange in color, that from Kusmi crops is pale yellow and that from others is dark yellow, east and south of Calcutta the lac is red, a pale red in Assam, and a dark red in Thailand.

While the life cycle of the insect produces two crops each year, there are numerous subdivisions of the entire lac crop, the most important crops being Bysaki, Jethwi, Katki and Kusmi.

The Jethwi and Kusmi lacs are the summer and winter crops of the kusum tree. Kusmi lac is of much better color and quality. The Bysaki and Katki lacs are the summer and winter crops from trees other than Kusum.

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