Page:The American Cyclopædia (1879) Volume III.djvu/603

CALICO PRINTING 597 From the material formerly used to effect this removal, which was a warm aqueous solution of cow dung, to which chalk was added if the cloth contained any free acid, the process was called dunging. Solutions of phosphate of soda and lime, with a little glue or some other forms of gelatine, have been substituted ; and more recently silicate of soda, silicate of lime, and arsenite of soda have been used, and the pro- cess is usually called cleansing. Not only is the useless portion of the mordant removed by this method, but the material employed as thicken- ing is also dissolved out, and the mordant which remains is the more firmly fixed by uniting with some of the constituents of the dung or of its substitutes. The cloth, after being passed twice through the dung becks, is several times washed in clean water, and is then ready for dyeing. Upon the care with which the dung- ing operation has been conducted, the delicate effects to be produced in great measure depend. The padding style is practised only with mine- ral colors. A colored ground is obtained by passing the cloth through a tub containing the mordant, and then between two rollers covered with blanket stuff, which is called the padding machine, and which presses out the superfluous liquid, and then through another similar appa- ratus which furnishes the color. If the object is to obtain a design on a white or colored ground, the cloth may be first mordanted in one padding machine and then printed in the other; or, as commonly practised, be first printed with one of the solutions, and then be padded or winced in the other. Wincing is the passing of goods back and forth a number of times over rollers placed in the dye becks below the surface of the dyeing liquid. The topical style is that in which the thickened colors and mordants are mixed and applied together to the cloth. These are sometimes permanent without the application of steam; and many cheap goods are sold, principally for exporta- tion, in which the fugitive colors, called spirit, fancy, or wash-off colors, are fixed neither by a mordant nor by steaming; but steam not only makes the color more permanent, but gives to it a brilliancy and delicacy of finish, and is usually employed. It is applied in a variety of methods by exposing the goods in a cask, steam chest, tight chamber, or recep- tacle called a lantern, or in that commonly used for calicoes, called the column, to an at- mosphere of steam at the temperature of 211 or 212 F. The column consists essentially of a hollow copper cylinder perforated with nu- merous holes, placed upright in a small apart- ment furnished with a fine for the exit of steam. Around the cylinder is rolled apiece of blanket, then a piece of white calico, and afterward several pieces of the printed and dried calico. The steam is then let into the cylinder for 30 or 40 minutes. The resist style is the printing of designs with some substance, as oil or a paste, which will protect the portions it covers from receiving any color, and which may sub- sequently be removed. They may be of a na- ture to act mechanically or chemically, and designed to resist the action either of a mordant or a color. The discharge style is producing white or bright figures upon a colored ground, by dissolving out the mordant in goods not yet dyed, or the dye if this has been first applied, and then printing the portions anew with the hand block. Chlorine and chromic acid are commonly used for removing organic coloring matter, and mordants are dissolved by printing with acid solutions. White figures are thus produced upon imitation turkey-red bandanna handkerchiefs by letting a solution of chlorine flow through hollow lead types of the form of the figure, the types in two corresponding plates, one above and the other underneath, being set in a press which contains a pile of 12 or 14 handkerchiefs. The plates are brought together with a pressure of about 300 tons, and this is sufficient to prevent the chlorine water from bleaching the fabric beyond.the limits of the types. The China-blue style is a method of forming a pattern, partly of white, and part- ly of different shades of blue, by first printing with indigo in its insoluble state, and then re- ducing this to the soluble state and dissolving it upon the cloth by immersing it in suitable preparations. In this process the dye is trans- ferred into the substance of the .fibres, where it is precipitated in the original insoluble form, and of the same variety of shades that were printed upon the goods. It is very curious that in this process the shades when dissolved do not run together, nor even spread upon the portions left white. Since the introduction of aniline colors, most of our knowledge of which we owe to the researches of Prof. A. W. Hof- mann of Berlin, much of the printing of calico has been done with them; and since the pro- duction in 1869 by Grabe and Liebermann from anthracene, one of the hydrocarbons obtained in the distillation of coal tar, of artificial aliza- rine, a substance identical in composition with the natural alizarine obtained from madder (see ALIZARINE), the substitution of coal-tar colors is likely to become still more general. The aniline colors are applied topically, the only mordant used being albumen (usually that obtained from dried blood, bleached by the action of ozone) or vegetable gluten, prepared in various ways. After the color has been ap- plied the goods are steamed and washed, and usually steamed a second time. Aniline black, which is obtained by the action of certain me- tallic chlorides upon aniline oil, is becoming much used in calico printing. To get the best results, pure aniline should be used. The black made by this method is developed upon the cloth itself by exposure subsequent to the printing. The aniline is mixed with nearly equal parts of chlorate of potash, chloride of ammonium, sulphate of copper, and tartaric acid, by means of a starch paste, and printed topically. Then the printed pieces are left 48 hours in a moist atmosphere of a temperature