Part 455

II.—The varnished labels of stock vessels often suffer damage from the spilling of the contents and the dripping after much pouring.

Formalin gelatin is capable of withstanding the baneful influence of ether, benzine, water, spirit of wine, oil, and most substances. The following method of applying the preservative is recommended: Having thoroughly cleaned the surface of the vessel, paste the label on and allow it to dry well. Give it a coat of thin collodion to protect the letters from being dissolved out or caused to run, then after a few minutes paint over it a coat of gelatin warmed to fluidity—5 to 25—being careful to cover in all the edges. Just before it solidifies go over it with a tuft of cotton dipped into a 40 per cent formalin solution. It soon dries and becomes as glossy as varnish, and may be coated again and again without danger of impairing the clear white of the label or decreasing its transparency.

«Leather Varnishes.»—I.—An excellent varnish for leather can be made from the following recipe: Heat 400 pounds of boiled oil to 212° F., and add little by little 2 pounds of bichromate of potash, keeping the same temperature. The addition of the bichromate should take about 15 minutes. Raise to 310° F., and add gradually during 1 hour at that temperature, 40 pounds Prussian blue. Heat for 3 hours more, gradually raising to 482° to 572° F., with constant stirring. In the meantime, heat together at 392° F., for 1⁠/⁠2 an hour, 25 pounds linseed oil, 35 pounds copal, 75 pounds turpentine, and 7 pounds ceresine. Mix the two varnishes, and dilute, if necessary, when cold with turpentine. The varnish should require to be warmed for easy application with the brush.

II.—Caoutchouc, 1 part; petroleum, 1 part; carbon bisulphide, 1 part; shellac, 4 parts; bone black, 2 parts; alcohol, 20 parts. First the caoutchouc is brought together with carbon bisulphide in a well-closed bottle and stood aside for a few days. As soon as the caoutchouc is soaked add the petroleum and the alcohol, then the finely powdered shellac, and heat to about 125° F. When the liquid appears pretty clear, which indicates the solution of all substances, the bone black is added by shaking thoroughly and the varnish is at once filled in bottles which are well closed. This pouch composition excels in drying quickly and produces upon the leather a smooth, deep black coating, which possesses a certain elasticity.

«METAL VARNISHES.»

The purpose of these varnishes is to protect the metals from oxidation and to render them glossy.

«Aluminum Varnish.»—The following is a process giving a special varnish for aluminum, but it may also be employed for other metals, giving a coating unalterable and indestructible by water or atmospheric influences: Dissolve, preferably in an enameled vessel, 10 parts, by weight, of gum lac in 30 parts of liquid ammonia. Heat on the water bath for about 1 hour and cool. The aluminum to be covered with this varnish is carefully cleaned in potash, and, having applied the varnish, the article is placed in a stove, where it is heated, during a certain time, at a suitable temperature (about 1062° F.).

«Brass Varnishes Imitating Gold.»—I.—An excellent gold varnish for brass objects, surgical or optical instruments, etc., is prepared as follows: Gum lac, in grains, pulverized, 30 parts; dragon’s blood, 1 part; red sanders wood, 1 part; pounded glass, 10 parts; strong alcohol, 600 parts; after sufficient maceration, filter. The powdered glass simply serves for accelerating the dissolving, by interposing between the particles of gum lac and opal.

II.—Reduce to powder, 160 parts, by weight, of turmeric of best quality, and pour over it 2 parts, by weight, of saffron, {726} and 1.700 parts, by weight, of spirit; digest in a warm place 24 hours, and filter. Next dissolve 80 parts, by weight, of dragon’s blood; 80 parts, by weight, of sandarac; 80 parts, by weight, of elemi gum; 50 parts, by weight, of gamboge; 70 parts, by weight, of seedlac. Mix these substances with 250 parts, by weight, of crushed glass, place them in a flask, and pour over this mixture the alcohol colored as above described. Assist the solution by means of a sand or water bath, and filter at the close of the operation. This is a fine varnish for brass scientific instruments.

«Bronze Varnishes.»—I.—The following process yields a top varnish for bronze goods and other metallic ware in the most varying shades, the varnish excelling, besides, in high gloss and durability. Fill in a bottle, pale shellac, best quality, 40 parts, by weight; powdered Florentine lake, 12 parts, by weight; gamboge, 30 parts, by weight; dragon’s blood, also powdered, 6 parts, by weight; and add 400 parts, by weight, of spirit of wine. This mixture is allowed to dissolve, the best way being to heat the bottle on the water bath until the boiling point of water is almost reached, shaking from time to time until all is dissolved. Upon cooling, decant the liquid, which constitutes a varnish of dark-red color, from any sediment that may be present. In a second bottle dissolve in the same manner 24 parts, by weight, of gamboge in 400 parts, by weight, of spirit of wine, from which will result a varnish of golden-yellow tint. According to the hue desired, mix the red varnish with the yellow variety, producing in this way any shade from the deepest red to the color of gold. If required, dilute with spirit of wine. The application of the varnish should be conducted as usual, that is, the article should be slightly warm, it being necessary to adhere strictly to a certain temperature, which can be easily determined by trials and maintained by experience. In order to give this varnish a pale-yellow to greenish-yellow tone, mix 10 drops of picric acid with about 3 parts, by weight, of spirit of wine, and add to a small quantity of the varnish some of this mixture until the desired shade has been reached. Picric acid is poisonous, and the keeping of varnish mixed with this acid in a closed bottle is not advisable, because there is danger of an explosion. Therefore, it is best to prepare only so much varnish at one time as is necessary for the immediate purpose.

«Brown Varnish.»—An excellent and quickly drying brown varnish for metals is made by dissolving 20 ounces of gum kino and 5 ounces of gum benjamin in 60 ounces of the best cold alcohol; 20 ounces of common shellac and 2 ounces of thick turpentine in 36 ounces of alcohol also give a very good varnish. If the brown is to have a reddish tint, dissolve 50 ounces of ruby shellac, 5 ounces balsam of copaiba, and 2 to 5 ounces of aniline brown, with or without 1⁠/⁠2 to 1 ounce of aniline violet, in 150 ounces of alcohol.

«Copper Varnishes.»—These two are for polished objects:

I.—One hundred and ten parts of sandarac and 30 parts of rosin, dissolved in sufficient quantity of alcohol; 5 parts of glycerine are to be added.

II.—Sandarac 10 parts Rosin 3 parts Glycerine 1⁠/⁠2 part Alcohol, a sufficient quantity.

Dissolve the two rosins in sufficient alcohol and add the glycerine.

«Decorative Metal Varnishes.»—

I II III IV Per Per Per Per Cent Cent Cent Cent

Seed lac 11.5 — — — Amber 7.6 — — 13.5 Gamboge 7.6 — — — Dragon’s blood 0.18 — — — Saffron 0.16 — — — Sandarac — 11.2 15.9 16.6 Mastic — 6.5 14.0 3.4 Elemi — 3.3 — — Venice turpentine — — 1.0 3.4 Camphor — 1.5 — — Aloe — — 7.0 — Alcohol 72.96 77.5 66.1 63.2

As will be seen, only natural colors are used. The so-called “gold lacquer” is composed as follows: Sandarac, 6.25 parts; mastic, 3 parts; shellac, 12.5 parts; Venice turpentine, 2.5 parts; aloe, 0.75 parts; gamboge, 3 parts; alcohol, 72 parts. The solution is filtered. Applied in a thin coating this varnish shows a handsome golden shade. Other metal varnishes have the following composition:

V VI VII

Per Per Per Cent Cent Cent

Shellac 17.5 — 18.0 Yellow acaroid gum 13.1 25.0 — Manila — 8.0 9.0 Alcohol 69.4 67.0 63.0

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«Gold Varnish.»—I.—A good gold varnish for coating moldings which produces great brilliancy is prepared as follows: Dissolve 3 pounds of shellac in 30 quarts of alcohol, 5 pounds of mastic in 5 quarts of alcohol, 3 pounds of sandarac in 5 quarts of alcohol, 5 pounds of gamboge in 5 quarts of alcohol, 1 pound of dragon’s blood in 1 quart of alcohol, 3 pounds of saunders in 5 quarts of alcohol, 3 pounds of turpentine in 3 quarts of alcohol. After all the ingredients have been dissolved separately in the given quantity of absolute alcohol and filtered, the solutions are mixed at a moderate heat.

II.—A varnish which will give a splendid luster, and any gold color from deep red to golden yellow, is prepared by taking 50 ounces pale shellac, 15 pounds Florentine lake (precipitated from cochineal or redwood decoction by alum onto strach, kaolin, or gypsum), 25 ounces of sandalwood, and 8 ounces of dragon’s blood. These in fine powder are dissolved on the water bath, in 500 ounces rectified spirit. The spirit must boil and remain, with occasional shaking, for 2 to 3 hours on the bath. Then cool and decant. In the meantime heat in another flask on the bath 30 ounces of gamboge in 500 ounces of the same spirit. The two liquids are mixed until the right color needed for the particular purpose in hand is obtained. Dilute with spirit if too thick. The addition of a little picric acid gives a greenish-yellow bronze but makes the varnish very liable to explode. These varnishes are applied to gently warmed surfaces with a soft bristle brush.

«Gold Varnish for Tin.»—This is obtained in the following manner: Spread out 5 parts, by weight, of finely powdered crystallized copper acetate in a warm spot, allowing it to lie for some time; then grind the powder, which will have acquired a light-brown shade, with oil of turpentine and add, with stirring, 15 parts, by weight, of fat copal varnish heated to 140° F. When the copper acetate has dissolved (in about 1⁠/⁠4 hour), the mass is filled in a bottle and allowed to stand warm, for several days, shaking frequently. The gold varnish is then ready for use. Coat the articles uniformly with it, and heat in a drying chamber, whereupon, according to the degree of temperature, varying colorations are obtained, changing from green to yellow, then golden yellow, and finally orange to brown. When good copal varnish is employed, the varnish will adhere very firmly, so that the article can be pressed without damage.

«Iron Varnishes.»—I.—A varnish obtained by dissolving wax in turpentine is useful. It gives a fairly hard coat, but has the drawback of filling up fine grooves, and so injuring the appearance of many metal ornaments.

II.—Shellac, 15 pounds; Siam benjamin, 13 pounds; alcohol, 80 pounds; formylchloride, 20 pounds.