the Week of Proper 28 / Ordinary 33
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Bible Encyclopedias
Textile-Printing
1911 Encyclopedia Britannica
or Textile " (see Weaving) is a general name for all woven fabrics (Lat. texere, to weave), and the art of ornamenting such fabrics by printing on designs or patterns in colour is very ancient, probably originating in the East. It has been practised in some form, with considerable success, in China and India from time immemorial, and the Chinese, at least, are known to have made use of engraved wood-blocks many centuries before any kind of printing was known in Europe. That the early Egyptians, too, were acquainted with the art is proved not merely by the writings of Pliny but by the discovery, in the Pyramids and other Egyptian tombs, of fragments of cloth which were undoubtedly decorated. by some method of printing.
The Incas of Peru, Chile and Mexico also practised textileprinting previous to the Spanish Invasion in 1519; but, owing to the imperfect character of their records before that date, it is impossible to say whether they discovered the art for themselves, or, in some way, learnt its principles from the Asiatics.
There is no doubt that India was the source from which, by two different channels, Europeans derived their knowledge of block-printing. By land its practice spread slowly westwards through Persia, Asia Minor and the Levant, until it was taken up in Europe - during the latter half of the 17th century. Almost at the same time the French brought directly by sea, from their colonies on the east coast of India, samples of Indian blue and white " resist " prints, and along with them, particulars of the processes by which they had been produced.
I. Technology Textile-printing was introduced into England in 1676 by a French refugee who opened works, in that year, on the banks of the Thames near Richmond. Curiously enough this is the first print-works on record; but the nationality and political status of its founder are sufficient to prove that printing was previously carried on in France. In Germany, too, textile printing was in all probability well established before it spread to England, for, towards the end of the 17th century, the district of Augsburg was celebrated for its printed linens - a reputation not likely to have been built up had the industry been introduced later than 1676.
On the continent of Europe the commercial importance of calico-printing seems to have been almost immediately recognized, and in consequence it spread and developed there much more rapidly than in England, where it was neglected and practically at a standstill for nearly ninety years after its introduction. During the last two decades of the 17th century and the earlier ones of the 18th new works were started in France, Germany, Switzerland and Austria; but it was only in 1738 that calico-printing was first practised in Scotland, and not until twenty-six years later that Messrs Clayton of Bamber Bridge, near Preston, established in 1764 the first print-works in Lancashire, and thus laid the foundation of what has since become one of the most important industries of the county and indeed of the country. At the present time calico-printing is carried on extensively in every quarter of the globe, and it is, pretty safe to say that there is scarcely a civilized country in either hemisphere where a print-works does not exist.
From an artistic point of view most of the pioneer work in calico-printing was done by the French; and so rapid was their advance in this branch of the business that they soon came to be acknowledged as its leading exponents.
Their styles of design and schemes of colour were closely followed even deliberately copied - by all other European printers; and, from the early days of the industry down to the latter half of the 19th century, the productions of the French printers in Jouy, Beauvais, Rouen, Alsace-Lorraine, &c., were looked upon. as representing " all that was best " in artistic calico-printing. This reputation was established by the superiority of their earlier work, which, whatever else it may have lacked, possessed in a high degree the two main qualities essential to all good James Pinckney Henderson, Democrat .
George T. Wood, P. Hansborough Bell, Elisha M. Pease, Hardin R. Runnels, Sam Houston, „ Edward Clark (lieutenant-governor, acting) Dem. Francis R. Lubbock, Democrat.. Pendleton Murray, Andrew J. Hamilton, provisional. James W. Throckmorton, Conservative Democrat Elisha M. Pease, provisional Edmund J. Davis, Republican Richard Coke, Democrat Richard B. Hubbard, Democrat Oran M. Roberts, „ John Ireland, Lawrence S. Ross, „ James S. Hogg, „ Charles A. Culberson, „ Joseph D. Sayers, „ Samuel W. T. Lanham, „ Thomas M. Campbell, „ decorative work, viz., appropriateness of pattern and excellency of workmanship. If, occasionally, the earlier designers permitted themselves to indulge in somewhat bizarre fancies, they at least carefully refrained from any attempt to produce those pseudo-realistic effects the undue straining after which in later times ultimately led to the degradation of not only French calico-printing design, but of that of all other European nations who followed their lead. The practice of the older craftsmen, at their best, was to treat their ornament in a way at once broad, simple and direct, thoroughly artistic and perfectly adapted to the means by which it had to be reproduced. The result was that their designs were characterized, on the one hand, by those qualities of breadth, flatness of field, simplicity of treatment and pureness of tint so rightly prized by the artist; and, on the other, by their entire freedom from those meretricious effects of naturalistic projection and recession so dear to the modern mind and so utterly opposed to the principles of applied art.
Methods of Printing. Broadly speaking textile-printing means the local application, to textile fabrics, of any colour in definite patterns or designs, but in properly printed goods the colour becomes part and parcel of the fibre, or, in other words, the latter is dyed so as to resist washing and friction. Textile-printing, then, may be looked upon as a form of dyeing; but, whereas in dyeing proper the whole fabric is uniformly covered with one colour, in printing one or more colours are applied to it in certain parts only, and in sharply defined patterns. In principle these two branches of textile colouring are closely allied, for the colouring matters used in each case are practically identical, but in practice the means whereby their respective objects are attained bear little or no resemblance to each other. In dyeing, for instance, it is sufficient, for the most part, to immerse the fabric in an aqueous solution of the dye-stuff, stirring it about constantly or otherwise manipulating it to prevent unevenness. In printing, however, the colour must be applied by special means - either by a wooden block, a stencil or engraved plates, or rollers - and thickened to prevent it from spreading, by capillary attraction, beyond the limits of the pattern or design. Many colours also contain, besides the colouring matter and thickening, all the substances necessary for their proper fixation on the cloth when the latter is simply passed through a subsequent process of steaming, and others again require to be subjected to many after treatments before they are thoroughly developed and rendered fast to light and washing.
There are five distinct methods at present in use for producing coloured patterns on cloth: (t) Hand block-printing.
(2) Perrotine or block-printing by machine.
(3) Engraved plate-printing.
(q.) Engraved roller-printing.
(5) Stencilling, which although not really a printing process may be classed here as one.
(t) Hand Block-Printing. - This process, though considered by some to be the most artistic, is the earliest, simplest and slowest of all methods of printing.
The blocks may be made of box, lime, holly, sycamore, plane or pear wood, the latter three being most generally employed. They vary in size considerably, but must always be between two and three inches thick, otherwise they are liable to warp - a defect which is additionally guarded against by backing the wood chosen with two or more pieces of cheaper wood, such as deal or pine. The several pieces or blocks are tongued and grooved to fit each other, and are then securely glued together, under pressure, into one solid block with the grain of each alternate piece running in a different direction.
The block, being planed quite smooth and perfectly flat, next has the design drawn upon, or transferred to it. This latter is effected by rubbing off, upon its flat surface, a tracing in lampblack and oil, of the outlines of the masses of the design. The portions to be left in relief are then tinted, between their outlines, in ammoniacal carmine or magenta, for the purpose of distinguishing them from those portions which have to be cut away. As a separate block is required for each distinct colour in the design, a separate tracing must be made of each and transferred (or " put on " as it is termed) to its own special block.
695 Having thus received a tracing of the pattern the block is thoroughly damped and kept in this condition by being covered with wet cloths during the whole process of " cutting." The blockcutter commences by carving out the wood around the heavier masses first, leaving the finer and more delicate work until the last so as to avoid any risk of injuring it during the cutting of the coarser parts. When large masses of colour occur in a pattern, the corresponding parts on the block are usually cut in outline, the object being filled in between the outlines with felt, which not only absorbs the colour better, but gives a much more even impression than it is possible to obtain with a large surface of wood. When finished, the block presents the appearance of flat relief carving, the design standing out like letterpress type.
Fine details are very difficult to cut in wood, and, even when successfully cut, wear down very rapidly or break off in printing. They are therefore almost invariably built up in strips of brass or copper, bent to shape and driven edgewise into the flat surface of the block. This method is known as " coppering," and by its means many delicate little forms, such as stars, rosettes and fine spots can be printed, which would otherwise be quite impossible to produce by hand or machine block-printing.
Frequently, too, the process of " coppering " is used for the purpose of making a mould, from which an entire block can be made and duplicated as often as desired, by casting. In this case the metal strips are driven to a predetermined depth into the face of a piece of lime-wood cut across the grain, and, when the whole design is completed in this way, the block is placed, metal face downwards. in a tray of molten type-metal or solder, which transmits sufficient heat to the inserted portions of the strips of copper to enable them to carbonize the wood immediately in contact with them and, at the same time, firmly attaches itself to the outstanding portions. When cold a slight tap with a hammer on the back of the limewood block easily detaches the cake of the type-metal or alloy and along with it, of course, the strips of copper to which it is firmly soldered, leaving a matrix, or mould, in wood of the original design. The casting is made in an alloy of low melting-point, and, after cooling, is filed or ground until all its projections are of the same height and perfectly smooth, after which it is screwed on to a wooden support and is ready for printing. Similar moulds are also made by burning out the lines of the pattern with a red-hot steel punch, capable of being raised or lowered at will, and under which the block is moved about by hand along the lines of the pattern.
In addition to the engraved block, a printing table and colour sieve are required. The table consists of a stout framework of wood or iron supporting a thick slab of stone varying in size according to the width of cloth to be printed. Over the stone table top a thick piece of woollen printer's blanket is tightly stretched to supply the elasticity necessary to give the block every chance of making a good impression on the cloth. At one end, the table is provided with a couple of iron brackets to carry the roll of cloth to be printed and, at the other, a series of guide rollers, extending to the ceiling, are arranged for the purpose of suspending and drying the newly printed goods. The " colour sieve " consists of a tub (known as the swimming tub) half filled with starch paste, on the surface of which floats a frame covered at the bottom with a tightly-stretched piece of mackintosh or oiled calico. On this the " colour sieve " proper, a frame similar to the last but covered with fine woollen cloth, is placed, and forms when in position a sort of elastic colour trough over the bottom of which the colour is spread evenly with a brush.
The modus operandi of printing is as follows: - The printer commences by drawing a length of cloth, from the roll, over the table, and marks it with a piece of coloured chalk and a ruler to indicate where the first impression of the block is to be applied. He then applies his block in two different directions to the colour on the sieve and finally presses it firmly and steadily on the cloth, ensuring a good impression by striking it smartly on the back with a wooden mallet. The second impression is made in the same way, the printer taking care to see that it fits exactly to the first, a point which he can make sure of by means of the pins with which the blocks are provided at each corner and which are arranged in such a way that when those at the right side or at the top of the block fall upon those at the left side or the bottom of the previous impression the two printings join up exactly and continue the pattern without a break. Each succeeding impression is made in precisely the same manner until the length of cloth on the table is fully printed. When this is done it is wound over the drying rollers, thus bringing forward a fresh length to be treated similarly.
If the pattern contains several colours the cloth is usually first printed throughout with one, then dried, re-wound and printed with the second, the same operations being repeated until all the colours are printed., Many modifications of block-printing have been tried from time to time, but of these only two - " tobying " and " rainbowing "- are of any practical value. The object of " tobey-printing " is to print the several colours of a multicolour pattern at one operation, and for this purpose a block with the whole of the pattern cut upon it, and a specially constructed " colour sieve " are employed. The sieve consists of a thick block of wood, on one side of which a series of compartments are hollowed out, corresponding roughly in shape, size and position to the various objects cut on the block. The tops of the dividing walls of these compartments are then coated with melted pitch, and a piece of fine woollen cloth is stretched over the whole and pressed well down on the pitch so as to adhere firmly to the top of each wall; finally a piece of string soaked in pitch is cemented over the woollen cloth along the lines of the dividing walls, and after boring a hole through the bottom of each compartment the sieve is ready for use. In operation each compartment is filled with its special colour through a pipe connecting it with a colour box situated at the side of the sieve and a little above it, so as to exert just sufficient pressure on the colour to force it gently through the woollen cloth, but not enough to cause it to overflow its proper limits, formed by the pitch-soaked string boundary lines.
The block is then carefully pressed on the sieve, and, as the different parts of its pattern fall on different parts of the sieve, each takes up a certain colour which it transfers to the cloth in the usual way. By this method of " tobying " from two to six colours may be printed at one operation, but it is obvious that it is only applicable to patterns where the different coloured objects are placed at some little distance apart, and that, therefore, it is of but limited application.
Block-printing by hand is a slow process; it is, however, capable of yielding highly artistic results, some of which are unobtainable by any other means, and it is, therefore, still largely practised for the highest class of work in certain styles.
(2) Perrotine-Printing.--The "perrotine " is a block-printing machine invented by Perrot of Rouen in 1834, and practically speaking is the only successful mechanical device ever introduced for this purpose. For some reason or other it has rarely been used in England, but its value was almost immediately recognized on the Continent, and although block-printing of all sorts has been replaced to such an enormous extent by roller-printing, the " perrotine " is still largely employed in French, German and Italian works. The construction of this ingenious machine is too complex to describe here without the aid of several detailed drawings, but its mode of action is roughly as follows: - Three large blocks (3 ft. long by 3 to 5 in. wide), with the pattern cut or cast on them in relief, are brought to bear successively on the three faces of a specially constructed printing table over which the cloth passes (together with its backing of printer's blanket) after each impression. The faces of the table are arranged at right angles to each other, and the blocks work in slides similarly placed, so that their engraved faces are perfectly parallel to the tables. Each block is moreover provided with its own particular colour trough, distributing brush, and woollen colour pad or sieve, and is supplied automatically with colour by these appliances during the whole time that the machine is in motion, The first effect of starting the machine is to cause the colour sieves, which have a reciprocating motion, to pass over, and receive a charge of colour from, the rollers, fixed to revolve, in the colour troughs. They then return to their original position between the tables and the printing blocks, coming in contact on the way with the distributing brushes, which spread the colour evenly over their entire surfaces. At this point the blocks advance and are gently pressed twice against the colour pads (or sieves) which then retreat once more towards the colour troughs. During this last movement the cloth to be printed is drawn forward over the first table, and, immediately the colour pads are sufficiently out of the way, the block advances and, with some force, stamps the first impression on it. The second block is now put into gear and the foregoing operations are repeated for both blocks, the cloth advancing, after each impression, a distance exactly equal to the width of the blocks. After the second block has made its impression the third comes into play in precisely the same way, so that as the cloth leaves the machines it is fully printed in three separate colours, each fitting into its proper place and completing the pattern. If necessary the forward movement of the cloth can be arrested without in any way interfering with the motion of the blocks - an arrangement which allows any insufficiently printed impression to be repeated in exactly the same place with a precision practically impossible in hand-printing. For certain classes of work the " perrotine " possesses great advantages over the hand-block; for not only is the rate of production greatly increased, but the joining up of the various impressions to each other is much more exact - in fact, as a rule, no sign of a break in continuity of line can be noticed in well-executed work. On the other hand, however, the " perrotine " can only be applied to the production of patterns containing not more than three colours nor exceeding five inches in vertical repeat, whereas hand block-printing can cope with patterns of almost any scale and containing any number of colours. All things considered, therefore, the two processes cannot be compared on the same basis: the " perrotine " is best for work of a utilitarian character and the hand-block for decorative work in which the design only repeats every 15 to 20 in. and contains colours varying in number from one to a dozen.
(3) Engraved Copperplate-Printing
The printing of textiles from engraved copperplates was first practised by Bell in 1770. It is now entirely obsolete, as an industry, in England, and is only [[[Technology]] mentioned here because it is, to a slight extent, still used in Switzerland for printing finely engraved borders on a special style of handkerchief the centre of which is afterwards filled in by blockprinting.
The presses first used were of the ordinary letterpress type, the engraved plate being fixed in the place of the type. In later improvements the well-known cylinder press was employed; the plate was inked mechanically and cleaned off by passing under a sharp blade of steel; and the cloth, instead of being laid on the plate, was passed round the pressure cylinder. The plate was raised into frictional contact with the cylinder and in passing under it transferred its ink to the cloth.
The great difficulty in plate-printing was to make the various impressions join up exactly; and, as this could never be done with any certainty, the process was eventually confined to patterns complete in one repeat, such as handkerchiefs, or those made up of widely separated objects in which no repeat is visible, like, for instance, patterns composed of little sprays, spots, &c.
(4) Roller-Printing, Cylinder-Printing, or Machine-Printing.- This elegant and efficient process was patented and worked by Bell in 1785 only fifteen years after his application of the engraved plate to textiles. It will probably remain a moot question as to whether he was the originator of the idea, but it is beyond doubt that he was the first man to put into practice the continuous printing of cloth from engraved copper rollers. Bell's first patent was for a machine to print six colours at once, but, owing probably to its incomplete development, this was not immediately successful, although the principle of the method was shown to be practical by the printing of one colour with perfectly satisfactory results. The difficulty was to keep the six rollers, each carrying a portion of the pattern, in perfect register with each other. This defect was soon overcome by Adam Parkinson of Manchester, and in 1785, the year of its invention, Bell's machine with Parkinson's improvement was successfully employed by Messrs Livesey, Hargreaves, Hall & Co., of Bamber Bridge, Preston, for the printing of calico in from two to six colours at a single operation.
What Parkinson's contribution to the development of the modern roller-printing machine really was is not known with certainty, but it was possibly the invention of the delicate adjustment known as " the box wheel," whereby the rollers can be turned, whilst the machine is in motion, either in or against the direction of their rotation.
In its simplest form the roller-printing machine consists of a strong cast iron cylinder mounted in adjustable bearings capable of sliding up and down slots in the sides of the rigid iron framework. Beneath this cylinder the engraved copper roller rests in stationary bearings and is supplied with colour from a wooden roller which revolves in a colour-box below it. The copper roller is mounted on a stout steel axle, at one end of which a cog-wheel is fixed to gear with the driving wheel of the machine, and at the other end a smaller cog-wheel to drive the colour-furnishing roller. The cast iron pressure cylinder is wrapped with several thicknesses of a special material made of wool and cotton - lapping - the object of which is to provide the elasticity necessary to enable it to properly force the cloth to be printed into the lines of engraving. A further and most important appliance is the " doctor " - a thin sharp blade of steel which rests on the engraved roller and serves to scrape off every vestige of superfluous colour from its surface, leaving only that which rests in the engraving. On the perfect action of this " doctor " depends the entire success of printing, and as its sharpness and angle of inclination to the copper roller varies with the styles of work in hand it requires an expert to " get it up " (sharpen it) properly and considerable practical experience to know exactly what qualities it should possess in any given case. In order to prevent it (the " doctor ") from wearing irregularly it is given a to-and-fro motion so that it is constantly changing its position and is never in contact with one part of the engraving for more than a moment at a time. A second " doctor " of brass or a similar alloy is frequently added on the opposite side of the roller to that occupied by the steel or " cleaning " doctor; it is known technically as the " lint doctor " from its purpose of cleaning off loose filaments or " lint " which the roller picks off the cloth during the printing operation. The steel or " cleaning doctor " is pressed against the roller by means of weighted levers, but the " lint doctor " is usually just allowed to rest upon it by its own weight as its function is merely to intercept the nap which becomes detached from the cloth and would, if not cleaned from the roller, mix with the colour and give rise to defective work.
The working of the machine will be best understood by referring to the accompanying diagrammatic sketch of a single colour (fig. 1).
Textileprinting-1.jpg
FIG. I.
A is the cast iron pressure cylinder; B the lapping with which it is usually wrapped; C the engraved copper printing roller; D the steel " cleaning doctor "; E the brass " lint doctor "; F the colour-furnishing roller; G the colour-trough or " box " in which the latter (F) works partly immersed in colour; X an endless woollen blanket continually circulating between the cloth to be printed (K) and the cylinder A; and K the cloth in question. In operation, the cylinder A is screwed down with an even pressure into frictional contact with the roller C; the machine is then set in motion, turning in the direction indicated by the arrows; the cloth is now introduced between A and C and as it leaves the machine fully printed it is carried over a series of drying cylinders situated above and heated by steam. The printing roller C is the only part of the machine directly connected with the motor or main drive of the works through the cog-wheel on its axle - the " mandril " - all the other parts deriving their motion from it, either by friction as in the case of the cylinder or by a spur wheel as in that of the colour-furnishing roller. The mode of printing is almost self-evident; the roller C revolving in the direction of the arrow takes colour from the " furnisher " F, the excess is scraped off by the " doctor " G and, in continuing its course, it comes in contact with the cloth K, which being pressed by the cylinder A into the engraving abstracts the colour therefrom and of course receives an exact impression of the engraved pattern.
Larger machines printing from two to sixteen colours are precisely similar in principle to the above, but differ somewhat in detail and are naturally more complex and difficult to operate. In a twelve-colour machine, for example, twelve copper rollers, each carrying one portion of the design, are arranged round a central pressure cylinder, or bowl, common to all, and each roller is driven by a common driving wheel, called the " crown " wheel, actuated, in most cases, by its own steam-engine or motor. Another difference is that the adjustment of pressure is transferred from the cylinder to the rollers which work in specially constructed bearings capable of the following movements: (I) Of being screwed up bodily until the rollers are lightly pressed against the central bowl; (2) of being moved to and fro sideways so that the rollers may be laterally adjusted; and (3) of being moved up or down for the purpose of adjusting the rollers in vertical direction. Notwithstanding the great latitude of movement thus provided each roller is furnished with a " box-wheel," which serves the double purpose of connecting or gearing it to the driving wheel, and of affording a fine adjustment. Each roller is further furnished with its own colour-box and doctors.
With all these delicate equipments at his command a machineprinter is enabled to fit all the various parts of the most complicated patterns with an ease, despatch and precision which are remarkable considering the complexity and size of the machine.
In recent years many improvements have been made in printing machines and many additions made to their already wonderful capacities. Chief amongst these are those embodied in the " Intermittent " and the " Duplex " machines. In the former any or all of the rollers may be moved out of contact with the cylinder at will, and at certain intervals. Such machines are used in the printing of shawls and " sarries " for the Indian market. Such goods require a wide border right across their width at varying distances - sometimes every three yards, sometimes every nine yards - and it is to effect this, with rollers of ordinary dimensions, that " intermittent " machines are used. The body of the " sarrie " will be printed, say for six yards with eight rollers; these then drop away from the cloth and others, which have up to then been out of action, immediately fall into contact and print a border or " crossbar," say one yard wide, across the piece; they then recede from the cloth and the first eight again return and print another six yards, and so on continually.
The " Duplex " or " Reversible " machine derives its name from the fact that it prints both sides of the cloth. It consists really of two ordinary machines so combined that when the cloth passes, fully printed on one side from the first, its plain side is exposed to the rollers of the second, which print an exact duplicate of the first impression upon it in such a way that both printings coincide. A pin pushed through the face of the cloth ought to protrude through the corresponding part of the design printed on the back if the two patterns are in good " fit." The advantages possessed by roller-printing over all other processes are mainly three: firstly, its high productivity - Io,000 to 12,000 yds. being commonly printed in one day of ten hours by a single-colour machine; secondly, by its capacity of being applied to the reproduction of every style of design, ranging from the fine delicate lines of copperplate engraving and the small " repeats " and limited colours of the " perrotine " to the broadest effects of block-printing and to patterns varying in " repeat " from I to 80 in.; and thirdly, the wonderful exactitilde with which each portion of an elaborate multicolour pattern can be fitted into its proper place, and the entire absence of faulty joints at its points of " repeat " or repetition - a consideration of the utmost importance in fine delicate work, where such a blur would utterly destroy the effect.
(5) Stencilling. - The art of stencilling is very old. It has been applied to the decoration of textile fabrics from time immemorial by the Japanese, and, of late years, has found increasing employment in Europe for certain classes of decorative work on woven goods for furnishing purposes.
The pattern is cut out of a sheet of stout paper or thin metal with a sharp-pointed knife, the uncut portions representing the part that is to be " reserved " or left uncoloured. The sheet is now laid on the material to be decorated and colour is brushed through its interstices.
It is obvious that with suitable planning an " all over " pattern may be just as easily produced by this process as by hand or machine printing, and that moreover, if several plates are used, as many colours as plates may be introduced into it. The peculiarity of stencilled patterns is that they have to be held together by "ties," that is to say, certain parts of them have to be left uncut, so as to connect them with each other, and prevent them from falling apart in separate pieces. For instance, a complete circle cannot be cut without its centre dropping out, and, consequently, its outline has to be interrupted at convenient points by " ties " or uncut portions. Similarly with other objects. The necessity for " ties " exercises great influence on the design, and in the hands of a designer of indifferent ability they may be very unsightly. On the other hand, a capable man utilizes them to supply the drawing, and when thus treated they form an integral part of the pattern and enhance its artistic value whilst complying with the conditions and the process.
For single-colour work a stencilling machine was patented in 1894 by S. H. Sharp. It consists of an endless stencil plate of thin sheet steel which passes continuously over a revolving cast iron cylinder. Between the two the cloth to be ornamented passes and the colour is forced on to it, through the holes in the stencil, by mechanical means.
(6) Other Methods of Printing. - Although most work is executed throughout by one or other of the five distinct processes mentioned above, combinations of them are not infrequently employed. Sometimes a pattern is printed partly by machine and partly by block; and sometimes a cylindrical block is used along with engraved copper-rollers in the ordinary printing machine. The block in this latter case is in all respects, except that of shape, identical with a flat wood or " coppered " block, but, instead of being dipped in colour, it receives its supply from an endless blanket, one part of which works in contact with colour-furnishing rollers and the other part with the cylindrical block. This block is known as a " surface " or " peg " roller. Many attempts have been made to print multicolour patterns with " surface " rollers alone, but hitherto with little success, owing to their irregularity in action and to the difficulty of preventing them from warping. These defects are not present in the printing of linoleum in which opaque oil colours are used - colours which neither sink into the body of the hard linoleum nor tend to warp the roller.
The printing of yarns and warps is extensively practised. It is usually carried on by a simple sort of " surface " printing machine and calls for no special mention.
Lithographic printing, too, has been applied to textile fabrics with somewhat qualified success. Its irregularity and the difficulty of printing " all over " patterns to " repeat " properly, have restricted its use to the production of decorative panels, equal in size to that of the plate or stone, and complete in themselves.
Engraving Of Copper Rollers The engraving of copper rollers is one of the most important branches of textile-printing and on its perfection of execution depends, in great measure, the ultimate success of the designs. Roughly speaking, the operation of engraving is performed by three different methods, viz. (I) By hand with a graver which cuts the metal away; (2) by etching, in which the pattern is dissolved out in nitric acid; and (3) by machine, in which the pattern is simply indented.
(i) Engraving by hand is the oldest and most obvious method of engraving, but is the least used at the present time on account of its slowness. The design is transferred to the roller from an oilcolour tracing and then merely cut out with a steel graver, prismatic in section, and sharpened to a bevelled point. It requires great steadiness of hand and eye, and although capable of yielding the finest results it is only now employed for very special work and for those patterns which are too large in scale to be engraved by mechanical means.
(2) In the etching process an enlarged image of the design is cast upon a zinc plate by means of an enlarging camera and prisms or reflectors. On this plate it is then painted in colours roughly approximating to those in the original, and the outlines of each colour are carefully engraved in duplicate by hand. The necessity for this is that in subsequent operations the design has to be again reduced to its original size and, if the outlines on the zinc plate were too small at first, they would be impracticable either to etch or print. The reduction of the design and its transfer to a varnished copper roller are both effected at one and the same operation in the pantograph machine. This machine is capable of reducing a pattern on the zinc plate from one-half to one-tenth of its size, and is so arranged that when its pointer or " stylus " is moved along the engraved lines of the plate a series of diamond points cut a reduced facsimile of them through the varnish with which the roller is covered. These diamond points vary in number according to the number of times the pattern is required to repeat along the length of the roller. Each colour of a design is transferred in this way to a separate roller. The roller is then placed in a shallow trough containing nitric acid, which acts only on those parts of it from which the varnish has been scraped. To ensure evenness the roller is revolved during the whole time of its immersion in the acid. When the etching is sufficiently deep the roller is washed, the varnish dissolved off, any parts not quite perfect being retouched by hand.
(3) In machine engraving the pattern is impressed in the roller by a small cylindrical " mill " on which the pattern is in relief. It is an indirect process and requires the utmost care at every stage. The pattern or design is first altered in size to repeat evenly round the roller. One repeat of this pattern is then engraved by hand on a small highly polished soft steel roller, usually about 3 in. long and z in. to 3 in. in diameter; the size varies according to the size of the " repeat " with which it must be identical. It is then repolished, painted with a chalky mixture to prevent its surface oxidizing and exposed to a red-heat in a box filled with chalk and charcoal; then it is plunged in cold water to harden it and finally tempered to the proper degree of toughness. In this state it forms the " die " from which the " mill " is made. To produce the actual " mill " with the design in relief a softened steel cylinder is screwed tightly against the hardened die and the two are rotated under constantly increasing pressure until the softened cylinder or " mill " has received an exact replica in relief of the engraved pattern. The " mill " in turn is then hardened and tempered, when it is ready for use. In size it may be either exactly like the " die " or its circumferential measurement may be any multiple of that of the latter according to circumstances.
The copper roller must in like manner have a circumference equal to an exact multiple of that of the " mill," so that the pattern will join up perfectly without the slightest break in line.
The modus operandi of engraving is as follows: - The " mill " is placed in contact with one end of the copper roller, and being mounted on a lever support as much pressure as required can be put upon it by adding weights. Roller and " mill " are now revolved together, during which operation the projection parts of the latter are forced into the softer substance of the roller, thus engraving it, in intaglio, with several replicas of what was cut on the original " die." When the full circumference of the roller is engraved, the " mill " is moved sideways along the length of the roller to its next position, and the process is repeated until the whole roller is fully engraved.
Preparation Of Cloth For Printing Goods intended for calico-printing ought to be exceptionally well bleached, otherwise mysterious stains, and other serious defects, are certain to arise during subsequent operations. Particulars of bleaching will be found in the article Bleaching.
The chemical preparations used for special styles will be mentioned in their proper places; but a general " prepare," employed for most colours that are developed and fixed by steaming only, consists in passing the bleached calico through a weak solution of " sulphated " or turkey red oil containing from 21 per cent. to 5 per cent. of fatty acid. Some colours are printed on pure bleached cloth, but all patterns containing alizarine red, rose and salmon shades, are considerably brightened by the presence of oil, and indeed very few, if any, colours are detrimentally affected by it.
Apart from wet preparations the cloth has always to be brushed, to free it from loose nap, flocks and dust which it picks up whilst stored. Frequently, too, it has to be " sheared " by being passed over rapidly revolving knives arranged spirally round an axle, which rapidly and effectually cuts off all filaments and knots, leaving the cloth perfectly smooth and clean and in a condition fit to receive impressions of the most delicate engraving. Some figured fabrics, especially those woven in checks, stripes and " cross-overs," require very careful stretching and straightening on a special machine, known as a " stenter," before they can be printed with certain formal styles of pattern which are intended in one way or another to correspond with the cloth pattern. Finally, all descriptions of cloth are wound round hollow wooden or iron centres into rolls of convenient size for mounting on the printing machines.
Preparation Of Colours The art of making colours for textile-printing demands both chemical knowledge and extensive technical experience, for their ingredients must not only be properly proportioned to each other, but they must be specially chosen and compounded for the particular style of work in hand. For a pattern containing only one colour any mixture whatever may be used so long as it fulfils all conditions as to shade, quality and fastness; but where two or more colours are associated in the same design each must be capable of undergoing without injury the various operations necessary for the development and fixation of the others.
All printing pastes whether containing colouring matter cr not are known technically as " colours," and are referred to as such in the sequence.
Colours vary considerably in composition. The greater number of them contain all the elements necessary for the direct production and fixation of the colour-lake. Some few contain the colouring matter alone and require various after-treatments for its fixation; and others again are simply " mordants " thickened. A mordant is the metallic salt or other substance which combines with the colouring principle to form an insoluble colour-lake, either directly by steaming, or indirectly by dyeing.
All printing colours require to be thickened, for the twofold object of enabling them to be transferred from colour-box to cloth without loss and to prevent them from " running " or spreading beyond the limits of the pattern.
Thickening Agents
The thickening agents in most general use as vehicles in printing, are starch, flour, gum arabic, gum senegal and gum tragacanth, British gum or dextrine and albumen.
With the exception of albumen all these are made into pastes, or dissolved, by boiling in double or " jacketed " pans, between the inner and outer casings of which either steam or water may be made to circulate, for boiling and cooling purposes. Mechanical agitators are also fitted in these pans to mix the various ingredients together, and to prevent the formation of lumps by keeping the contents thoroughly stirred up during the whole time they are being boiled and cooled.
Starch Paste
This is made by mixing 15 lb of wheat starch with a little cold water to a smooth creamy paste; a little olive oil is then added and sufficient water to bring the whole up to to gallons. The mixture is then thickened by being boiled for about an hour and, after cooling, is ready for use.
Starch is the most extensively used of all the thickenings. It is applicable to all but strongly alkaline or strongly acid colours. With the former it thickens up to a stiff unworkable jelly, while mineral acids or acid salts convert it into dextrine, thus diminishing its thickening power. Acetic and formic acids have no action on it even at the boil.
Flour paste is made in a similar way to starch paste. At the present time it is rarely used for anything but the thickening of aluminium and iron mordants, for which it is eminently adapted.
Gum arabic and gum senegal are both very old thickenings, but their expense prevents them from being used for any but pale delicate tints. They are especially useful thickenings for the light ground colours of soft muslins and sateens on account of the property they possess of dissolving completely out of the fibres of the cloth in the washing process after printing. Starch and artificial gums always leave the cloth somewhat harsh in " feel " unless they are treated specially, and are moreover incapable of yielding the beautifully clear and perfectly even tints resulting from the use of natural gums. Very dark colours cannot well be obtained with gum senegal or gum arabic thickenings; they come away too much in washing, the gum apparently preventing them from combining fully with the fibres. Stock solutions of these two gums are usually made by dissolving 6 or 8 lb of either in one gallon of water, either by boiling or in the cold by standing.
British gum or dextrine is prepared by heating starch. It varies considerably in composition - sometimes being only slightly roasted and consequently only partly converted into dextrine, and at other times being highly torrefied, and almost completely soluble in cold water and very dark in colour. Its thickening power decreases and its " gummy " nature increases as the temperature at which it is roasted is raised. The lighter coloured gums or dextrines will make a good thickening with from 2 to 3 lb of gum to one gallon of water, but the darkest and most highly calcined require from 6 to to lb per gallon to give a substantial paste. Between these limits all qualities are obtainable. The darkest qualities are very useful for strongly acid colours, and with the exception of gum senegal, are the best for strongly alkaline colours and discharges.
Like the natural gums, neither light nor dark British gums penetrate into the fibre of the cloth so deeply as pure starch or flour, and are therefore unsuitable for very dark strong colours.
Gum tragacanth, or " Dragon," is one of the most indispensable thickening agents possessed by the textile printer. It may be mixed in any proportion with starch or flour and is equally useful for pigment colours and mordant colours. When added to starch paste it increases its penetrative power, adds to its softness without diminishing its thickness, makes it easier to wash out of the fabric and produces much more level colours than starch paste alone. Used by itself it is suitable for printing all kinds of dark grounds on goods which are required to retain their soft clothy feel. A tragacanth mucilage may be made either by allowing it to stand a day or two in contact with cold water or by soaking it for twentyfour hours in warm water and then boiling it up until it is perfectly smooth and homogeneous. If boiled under pressure it gives a very fine smooth mucilage (not a solution proper), much thinner than if made in the cold.
Albumen
Albumen is both a thickening and a fixing agent for insoluble pigments such as chrome yellow, the ochres, vermilion and ultramarine. Albumen is always dissolved in the cold, a process which takes several days when large quantities are required. The usual strength of the solution is 4 lb per gallon of water for blood albumen, and 6 lb per gallon for egg albumen. The latter is expensive and only used for the lightest shades. For most purposes one part of albumen solution is mixed with one part of tragacanth mucilage, this proportion of albumen being found amply sufficient for the fixation of all ordinary pigment colours. In special instances the blood albumen solution is made as strong as 50 per cent., but this is only in cases where very dark colours are required to be absolutely fast to washing. After printing, albumenthickened colours are exposed to hot steam, which coagulates the albumen and effectually fixes the colours.
Formerly colours were always prepared for printing by boiling the thickening agent, the colouring matter and solvents, &c., together, then cooling and adding the various fixing agents. At the present time, however, concentrated solutions of the colouring matters and other adjuncts are often simply added to the cold thickenings, of which large quantities are kept in stock.
Colours are reduced in shade by simply adding more starch or other paste. For example, a dark blue containing 4 oz. of methylene blue per gallon may readily be made into a pale shade by adding to it thirty times its bulk of starch paste or gum, as the case may be. Similarly with other colours.
Before printing it is very essential to strain or sieve all colours in order to free them from lumps, fine sand, &c., which would inevitably damage the highly polished surface of the engraved rollers and result in bad printing. Every scratch on the surface of a roller prints a fine line in the cloth, and too much care, therefore, cannot be taken to remove; as far as possible, all grit and other hard particles from every colour.
The straining is usually done by squeezing the colour through fine cotton or silk cloths. Mechanical means are also employed for colours that are used hot or are very strongly alkaline or acid.
Styles Of Printing The widely differing properties of the hundreds of colouring matters now on the market give rise to many different styles of textile-printing. Generally speaking, these fall into the following four great divisions: (I) Direct printing.
(2) The printing of a mordant upon which the colour is afterwards dyed.
(3) The discharge style.
(4) The resist or reserve style.
The fact that each of these divisions is further sub-divided into many smaller divisions renders it out of the question to give more than a few typical examples of the various styles they include.
(I) Direct Printing. - This style is capable of application to almost every class of colour known. Its essential feature is that the colouring matter and its fixing agent are both applied to the fabric simultaneously. In some instances the fabric requires to be previously prepared for certain of the colours used along with those characteristic of the process; but this is one of many cases where two styles are combined, and it must be classed with the one which it most resembles.
(a) Application of Mordant Dye-Stuffs. - Mordant colours include both artificial and natural dye-stuffs (see also under Dyeing), the most important of all being alizarine, an artificial preparation of the colouring-principle of the madder root. With different metallic oxides alizarine forms different colour-lakes all exceedingly fast to light and soap. Aluminium mordant gives red and pink lakes; iron mordant, purples and lavenders; chromium yields maroons; and uranium gives grey shades. Mixture of iron and aluminium produce various tones of chocolate and brown. In addition to alizarine the following are a few of the more important mordant dye-stuffs employed in textile-printing: Alizarine orange with aluminium and chrome mordants for orange and warm brown shades respectively; alizarine bordeaux, with alumina, for violets; alizarine blue with chrome and zinc for quiet blue shades; coeruleine and alizarine viridine for greens and olives with chromium mordants; gallocyanine, chrome violet blue, alizarine cyanines, &c., with chromium for various shades of blue and violet; alizarine yellows and anthracene brown for yellows and fawn shades respectively with either aluminium or chrome mordants. The natural dye-stuffs belonging to this series are chiefly: logwood, with chromium and iron mordants, for blacks; Persian berries and quercitron bark, with aluminium, tin and chromium mordants, for colours ranging from brilliant yellow to quiet old golds and browns; catechu, with chromium, for very fast dark browns; and, occasionally, in mixtures, sapan-wood, peach-wood, Brazil-wood, and divi-divi extracts with any of the above-mentioned mordants.
The mordants are mostly in the form of acetates which are stable in the cold but decompose during the steaming process, and combine as hydroxides with the colours, forming and fixing on the fabric the insoluble lake.
Alizarine reds and pinks are the most complicated of the mordant colours, requiring for their proper production the addition of brightening agents, such as oxalate of tin, oils, tartaric acid, and also acetate of lime. This also applies to alizarine orange, but all the other colours are very simple to compound and are stable for a long time after making. Reds, pinks and oranges are best prepared freshly each day; their constituents are liable to combine if the colour stands twenty-four hours before printing.
The following types of recipes will give some idea of the way in which colours are mixed: - gallons thick starch and tragacanth paste.
„ alizarine (20 per cent. commercial paste).
„ nitrate of alumina, 18° Tw.
acetate of lime, 28° Tw.
oxalate of tin, 10° Tw.
„ 10 per cent. solution of tartaric acid.
gallons starch-tragacanth paste.
„ blue shade alizarine (20 per cent. paste). sulphocyanide of alumina, 18° Tw.
acetate of lime, 28° Tw.
oxalate of tin.
citrate of alumina, 40° Tw.
For reds and pinks the nitrate, sulphocyanide and citrate of alumina are generally preferred in practice to the acetate though the latter is also largely used. Oranges from alizarine orange are made similarly.
Purple. 91 gallons starch paste.
„ blue shade alizarine, 20 per cent.
acetic acid. „ acetate of lime, 28` Tw. „ acetate of iron, 24° Tw. Maroon. 51 gallons paste.
I „ alizarine, 20 per cent.
„ acetate of chrome, 32° Tw.
„ acetate of lime, 28° Tw.
Blues and the other colours are made by leaving out the lime in the last recipe and replacing the alizarine with another colour. Alizarine Blue. z lb alizarine blue shade (powd.). ( Light Shade.) I gallon water.
31 „ thick paste.
12 „ acetate of chrome, 40° Tw.
Logwood and other natural colours are specially boiled. Logwood Black. 15 lb starch.
io „ British gum.
42 gallons water.
acetic acid.
4 12 „ logwood extract, 48° Tw.
quercitron extract, 48° Tw.
Boil, cool and add: 2 lb red prussiate of potash. gallon water.
Acetate of chrome, 40° Tw.
2 oz. chlorate of potash.
Quercitron Yellow. 1 gallons quercitron extract, 48° Tw. 62 „ water.
II lb starch.
Boil, cool and add: 4 gallon acetate of chrome, 30° Tw.
The proportions here given are liable to variations according to circumstances. Indeed, no two works employ quite the same recipes, although the proportion of mordant to dye-stuff is pretty generally known and observed.
After printing, the goods are dried, steamed for one hour, and then washed and finished.
(b) Application of Basic Aniline Dye-Stuffs
These colours all form insoluble lakes with tannic acid; hence tannic acid is the common fixing agent of the group. Arsenic in combination with alumina also gives basic-colour lakes, but their poisonous character and their inferior fastness to most reagents considerably limit their application.
The more important basic dye-stuffs are: methylene blue, methyl violet, rhodamine, auramine yellow, safranine emerald green and indoine blue. Most of them are fairly fast to soaping, but towards the action of light they vary a good deal, methylene blue being perhaps as good as any, and the malachite greens the least stable.
Their application is simple. A solution of the colouring matter is added to the requisite quantity of starch paste or gum, and, when well mixed in, the tannin is added in the form of a solution also. If desired they may be boiled up like the extract dye-stuffs (logwood, &c.), but this is not necessary unless large quantities are required, when it would be more convenient to boil the whole at once than to mix small batches by hand.
| [TECHNOLOGY Red. 62 14 Pink. 61 14 3 Methylene blue will serve as a type of the method by which all basic colours are compounded. Blue. 2 gallons methylene blue, 10 per cent. solution in water and acetic acid. 6 „ thick starch paste. I „ tragacanth mucilage. I „ tannic acid solution, 50 per cent. Io gallons. All other basic colours are made up for printing in a similar way by replacing the blue with the required dye-stuff. After printing, goods containing basic dyes are " steamed," and passed through a solution of tartar emetic, or other salt of antimony, whereby an insoluble double tannate of antimony and colouring matter is formed, which constitutes a much faster colour than the single tannate of the dye-stuff. Basic colours may be printed along with " mordant " and albumen colours. (c) Application of Direct Dyeing ColoursThese colours have a natural affinity for the cotton fibre and therefore require no mordant. They are not very " fast," however, and, though used enormously in the dyeing of plain shades, they find but little employment in printing except for the tinting of printed goods, and for the " crepon " style, where the colours must be able to withstand the action of caustic soda. They are usually printed with the addition of a slightly alkaline salt (phosphate of soda) and sulphate of soda. Amongst the hundreds of direct colours equally suitable for printing mention may be made of erica for pinks; diamine sky-blue for blues; diamine violet, and diamine, chrysamine, chloramine and dianil yellows. In fact, most of the benzidine, diamine, dianil and Congo dye-stuffs can be used for printing, but with the exception of the yellows none of them will resist the action of light and washing to anything like the extent that " mordant " and basic colours will. The general formula for printing these colours is as follows 4 oz. colouring matter. gallon water. „ starch or tragacanth thickening. 4 oz. phosphate of soda. 2 oz. sulphate of soda. After printing, with direct colours, the goods are first steamed, then slightly washed in a weak tepid soap solution and finally finished. (d) Application of Pigment ColoursBefore the introduction of coal-tar colours, pigments and lakes played a much more important part in textile-printing than they do at present, though they are still largely used for certain styles of work. They form a series of colours more difficult to work than those already mentioned, but very fast to soap and light. Pigment colours, being insoluble mineral precipitates or lakes, can only be fixed on the fibre mechanically; consequently they require to be applied in conjunction with vehicles which cause them to adhere to the fabric in much the same way that paint adheres to wood. Of these vehicles, albumen is the most important and the best. It forms a smooth viscous solution with cold water, mixes readily with all the colours used in pigment printing, and possesses the property of coagulating when heated to the temperature of boiling water. When cloth printed with colours containing albumen is passed through hot steam or hot acid solutions, as in the indigo discharge style, the albumen coagulates, forming a tough insoluble colloidal deposit, which firmly fixes on the fibre any colour with which it is mixed. The colours chiefly employed in pigment printing are: chrome yellow and orange, Guignet's green or chrome green; artificial ultramarine; lamp black for greys; the various ochres for golds and browns; zinc oxide; vermilion and its substitutes, and occasionally lakes of the natural and artificial colouring matters. All these bodies are applied in exactly the same way and may be mixed together in any proportion to form compound shades. The amount of albumen necessary to fix them varies according to the depth of shade required (between Io and 25 per cent. of the total weight of the made-up printing colour), and although it is usually considered in text-books as a thickening agent it is rarely used as such in practice on account of its expense. As a rule the colouring matter is beaten up into a smooth paste with the necessary quantity of a strong solution of albumen and then reduced to its proper strength by the addition of tragacanth mucilage or starch paste. The main factor in the successful working of pigment colours is their fineness of division; the finer they are the better they print and the more beautiful is their quality of colour. If they are too coarse they give rise to innumerable defects, either by sticking in the engraving or by scratching the roller, or, if they print at all, by yielding uneven masses of colour, granular and speckled in appearance and quite unsaleable. Even when finally ground they are liable to clog the engraving of the rollers - a defect which is more or less successfully overcome by replacing the colour-furnishing roller in the printing machine by a revolving brush. The following formula of dark ultramarine blue will serve as a type of all other pigment printing colours: 24 Ib artificial ultramarine. Place in grinding machine and beat up gradually with 42 gallons 40 per cent. blood albumen solution. 21 „ tragacanth mucilage, 8 oz. per gallon. s 2 „ ammonia. „ glycerin. B i z „ turpentine. „ olive or cotton-seed oil. Make to 8 gallons with tragacanth or water, and grind the whole until perfectly homogeneous. The small quantities of ammonia, tu Copyright Statement These files are public domain. Bibliography Information
Chisholm, Hugh, General Editor. Entry for 'Textile-Printing'. 1911 Encyclopedia Britanica. https://www.studylight.org/encyclopedias/eng/bri/t/textile-printing.html. 1910.  Ads FreeProfile |