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Typo: A Monthly Newspaper and Literary Review, Volume 1
Trade Wrinkles
Trade Wrinkles.
Clear Shellac Varnish.—To get an absolutely clear solution of shellac has long been a desideratum, not only with microscopists, but with all others who have occasional need of the medium for cements, &c. It may be prepared (according to the National Druggist) by first making an alcoholic solution of shellac in the usual way; a little benzole is then added and the mixture well shaken. In the course of from twenty-four to forty-eight hours the fluid will have separated into two distinct layers, an upper alcoholic stratum, perfectly clear, and of a dark red color, while under it is a turbid mixture containing the impurities. The clear solution may be drawn off.
Mucilage of Acacia, or Gum Arabic.—It is usually stated that the preparation of this mucilage in the cold renders it less liable to become thick and muddy. This the Pharma. Zeitung, in a late issue, disputes upon the authority of H. Notfke, who recommends the hot treatment. The following is his plan. « By repeated experiments I have become convinced that the keeping qualities of mucilage gum arabic are improved by using hot water for solution. The water is first heated to boiling, then allowed to cool to about 80° C. (176° F.), and this is then poured upon the gum arabic, which had previously been carefully washed with cold distilled water. The whole is well covered, set aside in a cool place, and frequently stirred. Solution will take place rapidly. Any water lost by evaporation is replaced before straining. The straining must be done by passing the mucilage through a woollen strainer, previously washed repeatedly with distilled water. The strained mucilage should be filled into small bottles (2 to 8 oz.), which had previously been carefully dried in a drying oven, and must be still hot when filled. They should be filled to about three-fourths of the neck and at once corked, the cork, if possible, being pushed down so as to meet the surface of the mucilage. Mucilage thus prepared is clear and bright, and, if put up as here directed, keeps well, though it generally becomes faintly opalescent after a few days. But this happens also to mucilage prepared by the cold process. If the mucilage is heated in a steam bath, immediately after it has been strained, it will keep still better, but this second heating renders it quite opaque, which is not considered proper. »
(From the Inland Printer.)
Faint Lining.—This recipe is both simple and cheap: Dissolve a few ounces of gum arabic in water; use eight drops to a pint of ink; mix blue paste with warm water, and always strain through a cloth. If you wish a slightly darker blue, add a few drops of alcohol. This ink will run smoothly on any kind of paper.
White Ruling Ink.—To make a white ink that can be used in a ruling pen as India ink is used: Mix Chinese white with water containing enough gum arabic to prevent the immediate settling of the substance. Magnesium carbonate may be used in a similar way. They must be reduced to impalpable powder.
New Watermarking Process.—A German papermaker has invented a process for the imitation of water-marked papers by such means that the lines are produced after the paper has been printed or calendered. The design or device to be produced is drawn on thin paper and pasted on to cardboard, say of one inch in thickness. The design or device is then cut off and pasted on to a stout cardboard, and covered with a thin sheet of paper. If, then, the plate or relief thus produced is passed through a calender, together with a paper to be marked, the desired effect will be produced. The relief or plate may be used a great number of times.
Etching Metal Surfaces.—The following method of etching metallic surfaces, by which it appears possible to produce highly decorative effects, has recently been published. The article to be treated is electroplated with gold, silver, nickel, or other metal, and on this the design which it is desired to produce is traced with some suitable acid-resisting substance. It is them immersed in an acid-bath, by the action of which those portions of the surface which are left unprotected are deprived of their electroplated coating, and the naked metal beneath is given a frosted or dead appearance. The article is then well rinsed to remove all traces of the acid employed, and the acid-resisting varnish is removed by the use of alcohol, oil, or other proper solvent. The result is a frosted or dead-lustre surface of the original metal, upon which the design in the electroplated metal stands up in relief. If, for example, the article be one of copper and the plating silver, the design will be in silver upon a dead copper ground. It is manifest that the operation may be reversed, that is, the design to be reproduced, instead of being protected, as in the foregoing procedure, may be left unprotected, and the remainder of the electroplated surface covered. In this ease, the design would appear to be in dead copper on a silver ground.