The Manufacturer and Builder, A Practical Journal Of Industrial Progress
Vol. II. January 1870, No. 1.
Preparing cylinders for calico-printing.
Calico-Printing is the art of dyeing in various colors on cotton cloth. The fact that a variety of colors is required makes the manipulation difficult. The art was known and practiced by the Chinese and Indians from very early times. Calico was first brought into Europe from Calicut, a city in Hindustan, from which it receives its name. In the year 1498 the first cargo of Indian manufactures was shipped from Calicut for Europe. Modern science is a little too fast in laying claim to the first discovery of the use of mordants and protecting pastes. The Hindoos had a practical knowledge of their uses, as is abundantly proved by specimens of their handiwork in the museum of the Société Industrielle at Mülhausen. At this museum are implements for the application of mordants, and also of the protecting pastes, as well as many fine specimens of prints. There is one specimen, six yards long and three wide, the design of which is so complex that no single artist could have executed it in an onlinary lifetime.
Chemistry, like history, seems to repeat itself. Listen to the pointed words of Pliny upon the history of color-printing: "Robes and white vails are painted in Egypt in a wonderful way. They are first imbued, not with dyes, but with dye-absorbing drugs, by which, though they teem to be unaltered, yet, when immersed for a little while in a caldron of the boiling dye liquor, they are found to become painted. Yet, as there is only one color In the caldron, it is marvelous to see many colors imparted to the robe, in consequence of the influence of the excipient drug. Nor can this dye be washed out." What is this but a description of the use of mordants?
Calico-printing was not introduced into England until the latter part of the seventeenth century. The revocation of tho Edict of Nantes caused a large number of French people to flee from their homes. One of these Huguenot refugees established the first print-works in England, on the banks of the river Thames. Starting front this point, the art has attained a perfection in modes of execution to which the ancients could lay no claim.
The selfish instinct of the English manufacturers manifested itself in an attack of weavers upon the India importing house, caused by jealousy of the beautiful chintzes brought from Calicut.
Parliament supplemented this long-eared style of wisdom by prohibiting all printed calicoes, domestic as well as foreign, from being worn. In the year 1730, however, Parliament had grown a little wiser, and showed its moderation by permitting calicoes of home manufacture to be worn, provided they were woven with linen warp, coal a duty of sixpence paid upon each square yard. Those were the days when it cost something, to wear even calico, and such calicoes! No wonder they received favorable mention in wills, and became historic by doing service in several succeeding generationss. Then the dress outlasted the maiden; it was not us it is now - a new dress with every change of the moon. Then age added lustre to the gown; now if it be not new, it is nothing; and newness is often the only virtue our calicoes can boast.
Color is the great desideratum in calico-printing. Calicoes are made for the eye, and a brilliant color is sure to sell. It is said of woman, "Born a beauty is half-married;" and so of calicoes, beautiful colors and a ready market. "How will it look when made up?" is the artless question of the calico buyer. "Beautiful," "Very neat pattern," "Will make up splendidly," are some of the stereotyped phrases given in reply. Of course it is useless to say what buyers don't want to hear.
The beauty of prints, for the must part, depends upon the skillful application of coloring substances, technically called mordants, because they were supposed to "bite" a passage into the cloth for the colors. The process of coloring depends upon the nature of the cloth, as well as upon the coloring matter used. Different fabrics have very different attractions for coloring material, and in varying proportions. Wool takes in color the most readily, and silk next; while cotton and flax can only be permanently colored by indirect processes: hence the necessity for mordants.
A permanent color is attained only by meats of a chemical union between the material to be colored and the coloring matter. Very few dyes will unite directly with cotton fibre. There is scarcely a dye used extensively that imparts its color directly, except indigo.
A familiar division of dyes is into substantive colors, which impart their tint directly, and adjective colors, which impart color only through the medium of another color having an affinity fur both the cloth and the former color.
For example, if the color desired is a violet, the cloth is first treated with a solution of tin, and then placed in a dye of logwood. The solution of tin acts as a mortant, having an affinity for the logwood, and at the same lime for the cotton fibre. The two coloring substances united form a third, which, being precipitated upon the cloth, forms a chemical union with the cotton, and produces a permanent color. By using a salt of iron instead of tin, (for example, copperas,) the color obtained world be black. The application of different salts as mordants enables a dyer to get many different colors from a single dye, thereby increasing his resources to a great degree.
There is a third class of colors obtained largely from coal oil, and called fugitive colors, from the fact that they are not permanent. They are usually brit liant, and serve very well for certain kinda of fancy articles, such as curtains and bedspreads. They are greatly prized on account of their extreme brilliancy, notwithstanding they are by no means permanent. The brilliancy and early fading of the "Humboldt" and other "aniline" colors are well known to the shoppers of the fair sex.
In printing on calico, the cloth is prepared to receive the imprint of coloes by first being singed. A web of cotton cloth is passed rapidly over the surface of a red hot cylinder, with the nap next to the hot surface. A tolerably fair singeing is obtained by this means; but a much more efficient method is to pass the cloth rapidly over a surface of burning gas-jets. A puff of steam from a steam-jet thrown across the web, as it comes from the singer, prevents any accident from fire.
Bleaching follows the singeing, and makes the cloth perfectly pure and white. The most efficient bleaching agent known is chlorine, usually applied through the medium of chloride of lime. Chlorine has an intense affinity for hydrogen, and nearly all animal and vegetable colors contain hydrogen; hence chlorine, taking up this part of the compound, decomposes the color, and sets the fibre of the cloth free. Ozone and sulphur are also bleaching agents, but not so powerful as chlorine. Thorough washing is an important part of the bleaching process, as any particles of chlorine left in the fibre would eventually weaken it. When washed and dried, the cloth is ready to receive the colors.
We come now to the veritable process of printing itself. And here the three departments of designing, colors, and printing unite. The designer's thought is upon the copper cylinder - an engraving and a cylinder for each color. The color, or that part of it known as the mordant, is prepared, one for each kind of color, and the printer with his prepared cloth soon brings the three in contact. The result, of course, is calico. The plain bleached cotton cloth is wound into rolls, some two feet in diameter, from which it is unrolled and passed over a largo cylinder, around which are placed the engraved copper cylinders, and white the cloth is passing over the surface of this large cylinder, it comes in contact with the copper cylinder, and receives the color from the engraved lines similarly to the way in which paper receives an impress from type. The mechanical operation may be gathered from the accompanying engraving.
Machine for printing calico.
A represents the large cylinder, three feet in diameter, over which passes a strong belting of rubber, or thick, soft cloth, underneath the cotton web, B, which is supplied from behind, and passes up into the second story at C, after it is printed. The largo cylinder, A, is turned by steam, and the printing-cylinders are supplied with motion from it by means of n uniform set of cog-wheels, so that all the printing-cylinders may be run at precisely the same rate. One of the engraved copper cylinders is shown at T. Just behind D, and slightly beneath it, may be placed a second; just behind that a third, and so on for any number, until one half the circumference of A is occupied. The cloth, B, passes rapidly between A and tho printing-cylinders, partly by the motion of A, and partly by the force of a revolving cylinder, upon which it is rolled in the second story.
The engraved figure upon the copper cylinder is sunk about one sixteenth of an inch beneath the surface; but the pressure of the cylinder, D, upon the web, B, is sufficient to deposit the coloring material which is within the engraved lines.
In a color-box beneath D revolves a cylinder, F, in contact with D. F is covered with a soft material, as wool or woolen cloth, and distributes the coloring matter all over too engraved cylinder, D. The color-box is kept supplied by an attendant, who occasionally dips a quantity of color from the tub, G, and pours it into the box.
It will be asked, How the engraved cylinder, D, can imprint just the engraving upon its surface on the cloth in passing, when the whole surface is covered with color? and besides, the unengraved portion must come in contact with tho cloth first. This feat is accomplished by an ingenious device called the doctor. The doctor is a plain steel blade, which lies close upon the surface of the engraved cylinder, just after it leaves the cylinder, F, which supplies the color. Before D has time to come in contact with B, the doctor removes all the color from the surface of D, except just what remains within the engraved lines. The work of the doctor is so complete that the surface of the copper, after passing it, would not soil a cambric handkerchief. The coloring material is thus left within the engraved lines only, and a slight pressure stamps the impression upon the cloth. The action of one cylinder, D, represents the working of all. Thus, beginning with a cylinder on the back side of the large cylinder, A, the cloth receives one color; in an instant it comes to a second, and gets another color; then a third; then a fourth, and so on, till lastly it comes to D, and receives a fifth, or perhaps a twelfth, which completes a print containing so many different colors. Calico may be printed thus at almost any rate. Twenty-five yards per minute would be very good speed. The adjustment of the different cylinders is a delicate operation, requiring great care and skill. This will be apparent when it is remembered that, in the small space of one sixteenth of a square inch, three or more of these cylinders must deposit their colors, each one in its own place, and so as not to interfere with or avoid taw one that has gone before it. The colors are prevented from running into each other by means of protecting pastes, and by being dried immediately after they are printed. The protecting paste is a sort of gum or starch, that holds the color from spreading in the fibre of the cloth.
The color printed by the engraved cylinder is the mordant, and is afterward brought out by passing the cloth through a dye of logwood.
Modern calico printing is much more rapid than the old style of block-printing by hand. Each piece then required the application of the block 448 limes for a single color, 896 for two, 1344 for three, 1792 for four, and 2240 times for five colors. One cylinder-printer, attended by one man and one boy, will do as much work as 100 block-printers with 100 boys. There is also n great saving of time and labor in the methods of engraving.
The metal cylinders were formerly prepared after the ordinary method of copperplate engraving, the design being cut in a surface of copper instead of in relief, and in this way the entire surface of the cylinder teas engraved. But a more ingenious method, invented in England, has since been substituted for this costly process. A small cylinder of soft steel is first engraved with a complete section of the pattern sunk in its surface; it is then hardened, and made to transfer the device to another cylinder of the same size, but of softer material. In this second cylinder the design is necessarily raised on the surface. This cylinder is hardened in its turn, and then made to pass, with great pressure, over every portion of the long copper cylinder intended for use in the printing, leaving the design impressed on its entire surface. By this means great saving of labor is effected in the process of engraving, and the manufacturer is enabled to employ patterns of a more minute and complicated character than would otherwise be conveniently at his disposal. The cylinders, like the wood blocks, must be as numerous as the colors employed in the design. Where several colors are to be used, the greatest nicety is necessary in the preparation of the cylinders, and afterwards in their adjustment while printing, so that each color may be impressed exactly on that portion of the pattern intended to receive it.
Another mode of preparing the cylinder is the following: The copper surface is covered with a perfectly even coat of varnish, which is generally applied while warm. Then the effects or designs which it is desired to produce upon the cylinder are drawn on the varnish with a diamond-pointed tracer. The cylinder is finally subjected to the action of a strong acid, which eats into all those parts of the surface left bare by the point of the tracer, and produces in the metal lines corresponding to those drawn by the designer on the varnish.
After the design is thus transferred to the cylinder, it is necessary to provide for the printing of those portions of the material which will fall between the various groups of which the pattern is composed. For this purpose lines destined to recceive the color are made over all such portions of the cylinder. This is done in a manner similar to the process we have just described; the cylinder is again entirely covered with varnish, and the lines are impressed all over its surface by means of a small "mill." Then the cylinder is presently exposed to the acid again for these lines to be eaten in. But as the pattern itself, as well as the spaces left between its several sections, has now been scored by the action of the mill, it is necessary, before putting the cylinder in the acid, to fill up all those portions of the original design which have been touched by the second process This is done by painting, in the manner shown in our engraving, girls being employed for the work. When the cylinders are finally engraved, electrotype casts are taken of them in the usual manner.
A most wonderful saving of time occurs in the process of bleaching. During the sixteenth and seventeenth centuries the Dutch monopolized the art of bleaching. It was done mainly by spreading cloths upon the grass, and exposing them to moisture and sunlight. The time required was from four to eight months. The bleaching was hastened a little by "souring"—that is, steeping cloth in sour milk. About the middle of the eightteenth century (1750), the application of sulphuric acid was discovered, which shortened the process very greatly. Chlorine was discovered in 1774; and in 1785, Berthollet ascertained that it would decompose vegetable colors, and suggested its use for bleaching. James Watt soon after applied it with success. Bleaching process that required form four to eight months a century since are now completed in as many hours. The bleaching of the cotton and linen fabrics demanded by the world to-day could scarcely be perdormed by its entire present civilized population, if confined to the methods of one hundred years ago. It would be difficult to find space to spread out the webs. One single establishment, near New-York City, turns out prints enough yearly to cover more than 40,000 acres. And some of the largo establishments, both inl England and the United States, do more than twenty times this amount of work.