BRONZE POWDERS, LIQUID BRONZES, BRONZE SUBSTITUTES, AND BRONZING
Bronze Powders.
Gold bronze is a mixture of equal parts of oxide of tin and sulphur, which are heated for some time in an earthen retort. Silver bronze is a mixture of equal parts of bismuth, tin, and mercury, which are fused in a crucible, adding the mercury only when the tin and the bismuth are in fusion. Next reduce to a very fine powder. To apply these bronzes, white of egg, gum arabic, or varnish is used. It is preferable to apply them dry upon one of the above-named mediums serving as size, than to mix them with the liquids themselves, for in the latter case their luster is impaired.
Simple Coloring Of Bronze Powder.
General Directions For Bronzing.
Liquid Bronzes.
Liquid Bronzes.
II.—Or else carefully mix 100 parts of finely ground dammar rosin with 30 parts of calcined soda and heat to fusion, in which state it is maintained 2 or 3 hours with frequent stirring. Let cool, grind the turbid mass obtained, and pour a little coal benzine or petroleum benzine over it in a flask. By repeated shaking of the flask the soluble portion of the molten mass is dissolved; filter after allowing to settle; into the filtrate put 300 to 400 parts of bronze powder of any desired shade, the brocades being especially well adapted for this purpose. If the metallic powder remains distributed over the mass for a long time it is of the right consistency; if it deposits quickly it is too thin and a part of the solvent must be evaporated before stirring in the bronze powder.
III.—A liquid bronze, which, while it contains no metallic constituent, yet possesses a metallic luster and a bronze appearance, and answers excellently for many purposes, is made as follows: Dissolve by the aid of gentle heat 10 parts of aniline red and 5 parts of aniline purple in 100 parts of alcohol. When solution is complete, add 5 parts of benzoic acid, raise the heat, and let boil from 5 to 10 minutes, or until the greenish color of the mixture passes over to a clear bronze brown. For “marbling” or bronzing paper articles, this answers particularly well.
Incombustible Bronze Tincture.
General Formulas For Bronzing Preparations.
II.—Dissolve 120 parts sulphate of copper and add 120 parts chipping of tin; stir well and gather the precipitating copper. After complete drying, grind very finely in boiled linseed oil and turpentine.
III.—Melt in a crucible 60 parts sulphur and 60 parts stannic acid; stir with a clay tube until the mixture takes on the appearance of Dutch gold and pour out. When cold mix the color with boiled linseed oil and turpentine, adding a small quantity of drier. These three bronzes must be covered with a pale, resistant {136} lacquer, otherwise they will soon tarnish in rooms where gas is burned.
Florentine Bronzes.
II.—If the article is of brass it must be given a coat of copper by means of the battery. Next dip a brush in olive oil and brush the piece uniformly; let dry for 5 or 6 hours and place in sawdust. Then heat the article on a moderate charcoal dust fire.
Preparation Of French Bronze.
How To Bronze Metals.
If, instead of lead acetate, an equal weight of sulphuric acid (1 1/2 ounces) is added to the sodium hyposulphite and the process carried on as before, the brass becomes coated with a very beautiful red, which changes to green, and finally a splendid brown with a green and red iridescence. This last is a very durable coating and may be especially recommended. It is very difficult to obtain exact shades by this process without some experience. The thorough cleansing of all articles from grease by boiling in potash is absolutely necessary to success. By substituting other metal salts for the lead acetate many changes in tints and quality of the coatings can also be effected.
When this mixture is heated to a temperature a little below the boiling point it precipitates sulphide of lead in a state of fine division. If some metal is present some of the lead is precipitated on the surface and, according to the thickness of the layer, different colors are produced. To produce an even color the articles must be evenly heated. By immersion of brass articles for 5 minutes the same may be coated with colors varying from gold to copper red, then to carmine, dark red, and from light blue to blue white, and at last a reddish white, depending on the time the metal remains in the solution and the temperature used. Iron objects treated in this solution take a steel-blue color, zinc a brown color. In the case of copper objects a golden yellow cannot be obtained.
New Bronzing Liquid.
A Bronze For Brass.
To Bronze Copper.
Spread on the copper object a solution composed of:
| Acetate or chlorhydrate of ammonia | 30 parts |
| Sea salt | 10 parts |
| Cream of tartar | 10 parts |
| Acetate of copper | 10 parts |
| Diluted acetic acid | 100 parts |
Let dry for 24 to 48 hours at an ordinary temperature. The surface of the metal will become covered with a series of varying tints. Brush with a waxed brush. The green portions soaked with chlorhydrate of ammonia will assume a blue coloring, and those treated with carbonate will be thick and darkened.
Bronzing And Patinizing Of Small Zinc Articles.
Bronzing Of Zinc.
Bronze Gilding On Smooth Moldings.
Incombustible Bronze Tincture.
Bronzing Engraved Ornaments.
Durable Bronze On Banners.
Bronze Substitutes.
The following recipe is used in making imitation gold bronzes:
| Sandarac | 50 parts |
| Mastic | 10 parts |
| Venice turpentine | 5 parts |
| Alcohol | 135 parts |
| In the above dissolve: | |
| Metanil yellow and gold orange | 0.4 parts |
| and add | |
| Aluminum, finely powdered | 20 parts |
| and shake. | |
If a deeper shade is desired it is well to use ethyl orange and gold orange in the same proportion, instead of the dyes.
For the production of imitation copper bronze take the above-mentioned rosin mixture and dissolve therein only gold {138} orange 0.8 parts, and add aluminum 20 parts, whereby a handsome copper color is produced. Metanil yellow 0.4 parts without gold orange gives with the same amount of lacquer a greenish tone of bronze. The pigments must not be made use of in larger quantities, because the luster of the bronze is materially affected. Only pigments of certain properties, such as solubility in alcohol, relative constancy to reductive agents, are suitable; unsuitable are, for instance, naphthol yellow, phenylene-diamin, etc. Likewise only a lacquer of certain composition is fit for use, other lacquers of commerce, such as zapon (celluloid) lacquer being unsuitable. The bronzes prepared in this manner excel in luster and color effect; the cost is very low. They are suitable for bronzing low-priced articles, as tinware, toys, etc. Under the action of sun and moisture the articles lose some of their luster, but objects kept indoors such as figures of plaster of Paris, inkstands, wooden boxes, etc., retain their brilliancy for years.
Some use powdered aluminum and yellow organic dyestuffs, such as gold orange. These are employed together with a varnish of certain composition, which imparts the necessary gloss to the mixture.
Bronze Coloring:
To Color Bronze.
Patent bronzes (products colored by means of aniline dyes) have hitherto been used in the manufacture of toys and de luxe or fancy paper, but makers of wall or stained paper have recently given their attention to these products. Wall—or moiré—paper prepared with these dyes furnishes covers or prints of silken gloss with a peculiar double-color effect in which the metallic brilliancy characteristic of bronze combines with the shades of the tar pigments used. Very beautiful reliefs, giving rise to the most charming play of colors in perpendicular or laterally reflected light, are produced by pressing the paper lengths or web painted with aniline-bronze dyes. The brass brocade and tin bronzes serve as bases for the aniline dyes; of the tar pigments only basic aniline dyes soluble in alcohol are used. In coloring the pulverized bronze care must be taken that the latter is as free as possible from organic fats. Tar dyes should be dissolved in as concentrated a form as possible in alcohol and stirred with the bronze, the pigment being then fixed on the vehicle with an alcoholic solution of tannin. The patent bronze is then dried by allowing the alcohol to evaporate. This method of coloring is purely mechanical, as the tar dyes do not combine with the metallic bronze, as is the case with pigments in which hydrate of alumina is used. A coating of aniline bronze of this kind is therefore very sensitive to moisture, unless spread over the paper surface with a suitable protective binding medium, or protected by a transparent coat of varnish, which of course must not interfere with the special color effect.
Pickle For Bronzes.
Imitation Japanese Bronze.
Green Bronze On Iron.
Blue Bronze.
Bronzing With Soluble Glass.
Brown Oxidation On Bronze.
Bronze Powders:
See also Plating for general methods of bronzing, and Varnishes.
Gold And Silver Bronze Powders.
By the use of various salt solutions or acidulated substances other shades can be imparted to bronze. In water containing sulphuric acid, nitric acid, or hydrochloric acid, it turns a bright yellow; by treatment with a solution of crystallized verdigris or blue vitriol in water it assumes more of a reddish hue; other tints are obtained with the aid of cooking salt, tartar, green vitriol, or saltpeter in water.
Gold bronze is also obtained by dissolving gold in aqua regia and mixing with a solution of green vitriol in water, whereupon the gold falls down as a metallic powder which may be treated in different ways. The green vitriol, however, must be dissolved in boiling water and mixed in a glass, drop by drop, with sulphuric acid and stirred until the basic iron sulphate separating in flakes has redissolved. Another way of producing gold bronze is by dissolving gold in aqua regia and evaporating the solution in a porcelain dish. When it is almost dry add a little pure hydrochloric acid and repeat this to drive out all the free chlorine and to produce a pure hydrochlorate of gold. The gold salt is dissolved in distilled water, taking 1/2 liter per ducat (3 1/2 grams fine gold); into this solution drop, while stirring by means of a glass rod, an 8° solution (by Beaumé) of antimony chloride, as long as a precipitate forms. This deposit is gold bronze, which, dried after removal of all liquids, is chiefly employed in painting, for bronzing, and for china and glass decoration.
Metallic gold powder is, furthermore, obtained by dissolving pure and alloyed gold in aqua regia and precipitating it again by an electro-positive metal, such as iron or zinc, which is placed in the liquid in the form of rods. The gold is completely separated thereby. The rods must be perfectly clean and polished bright. The color of the gold bronze depends upon the proportions of the gold. In order to further increase the brilliancy the dried substance may still be ground. {140}
Mosaic Gold.
The handsomest, purest, and most gold-like mosaic gold is obtained by melting 12 parts of pure tin, free from lead, and mixing with 6 parts of mercury to an amalgam. This is mixed with 7 parts of flowers of sulphur and 6 parts of sal ammoniac, whereupon the mass is subjected for several hours to a heat which at first does not attain redness, but eventually when no more fumes are generated is increased to dark-red heat. This operation is conducted either in a glass retort or in an earthenware crucible. The sal ammoniac escapes first on heating, next vermilion sublimates and some stannic chloride, while the mosaic gold remains on the bottom, the upper layer, consisting of lustrous, golden, delicately translucent leaflets, being the handsomest mosaic gold.
Genuine Silver Bronze.
Imitation Silver Bronze.
Mosaic Silver.
BRONZE VARNISHES: See Varnishes.
BRONZING SOLUTIONS FOR PAINTS: See Paints.
BRONZING OF WOOD: See Wood.
BROOCHES, PHOTOGRAPHS ON: See Photography.
BROWN OINTMENT: See Ointments.
BROWNING OF STEEL: See Plating.
BROWNSTONE, IMITATION: See Brick Stain.
BRUNETTE POWDER: See Cosmetics.