Henley's Twentieth Century Formulas, Recipes and Processes. Various

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СКАЧАТЬ arabic and a little glycerine. Then apply the bronze solution, prepared with dammar and one-tenth varnish. Instead of gum arabic with glycerine, gelatine glue may also be employed as an underlay.

      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.

      —Bronze articles acquire handsome tempering colors by heating. In order to impart an old appearance to new objects of bronze, they may be heated over a flame and rubbed with a woolen rag dipped in finely powdered graphite, until the desired shade is attained. Or else a paste is applied on the article, consisting of graphite 5 parts and bloodstone 15 parts, with a sufficient quantity of alcohol. After 24 hours brush off the dry powder. A hot solution composed of sal ammoniac 4 parts, sorrel salt 1 part, vinegar 200 parts, may also be brushed on. Another way is to dip the pieces into a boiling solution of cupric acetate 20 parts, and sal ammoniac 10 parts, dissolved in 60 to 100 parts of vinegar.

      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.

      —Sulphuric acid, 1,000 parts; nitric acid, 500 parts; soot, 10 parts; sea salt, 5 parts.

      Imitation Japanese Bronze.

      —When the copper or coppered article is perfectly dry and the copper or copper coating made brilliant, which is produced by rubbing with a soft brush, put graphite over the piece to be bronzed so that the copper is simply dyed. Wipe off the raised portions with a damp cloth, so that the copper makes its appearance. Next put on a thin coat of Japanese varnish; wipe the relief again and let dry. Apply 1 or 2 coats after the first is perfectly dry. Handsome smoked hues may be obtained by holding the bronze either over the dust of lighted peat or powdered rosin thrown on lighted coal, so as to obtain a smoke which will change the color of the varnish employed. The varnish must be liquid enough to be worked easily, for this style of bronzing is only applicable to brass.

      Green Bronze On Iron.

      —Abietate of silver, 1 part; essence of lavender, 19 parts. Dissolve the abietate of silver in the essence of lavender. After the articles have been well pickled apply the abietate-of-silver solution with a brush; next place the objects in a stove and let the temperature attain about 150° C.

      Blue Bronze.

      —Blue bronze is {139} produced by the wet process by coloring white bronze (silver composition) with aniline blue. A blue-bronze color can be produced in the ordinary way from white-bronze color, the product of pure English tin, and with an alum solution consisting of 20 parts of alum in 4,500 parts of water boiled for 5 hours and washed clean and dried. The bronze prepared in this manner is placed in a porcelain dish, mixed with a solution of 15 parts of aniline blue in 1,500 parts of alcohol, stirring the bronze powder and liquid until the alcohol has evaporated entirely and the bronze color becomes dry. This manipulation must be repeated 6 or 8 times, until the desired blue shade is reached. When the bronze is dark enough it is washed out in warm water, and before entirely dry 1 ta­ble­spoon­ful of petroleum is poured on 2 pounds of bronze, which is intimately mixed and spread out into a thin layer, exposed to the air, whereby the smell is caused to disappear in a few days.

      Bronzing With Soluble Glass.

      —To bronze wood, porcelain, glass, and metal by means of a water-glass solution, coat the article with potash water-glass of 30° Bé. and sprinkle on the respective bronze powder.

      Brown Oxidation On Bronze.

      —Genuine bronze can be beautifully oxidized by painting it with a solution of 4 parts of sal ammoniac and 1 part of oxalium (oxalate of potash) in 200 parts of vinegar, allowing it to dry, and repeating the operation several times. These articles, protected against rain, soon lose the unpleasant glaring metallic luster and assume instead a soft brown tint, which bronze articles otherwise acquire only after several years’ exposure to the atmosphere. A beautiful bronze color which will remain unaffected by heat can be imparted to bronze articles by the following process: The object is first washed in a solution of 1 part of crystallized verdigris and 2 parts of sal ammoniac in 260 parts of water, and then dried before an open fire till the green color begins to disappear. The operation is repeated 10 to 20 times, but with a solution of 1 part of verdigris crystals and 2 parts of sal ammoniac in 600 parts of water. The color of the article, olive green at first, СКАЧАТЬ