Printing
From Britannica 11th Edition (1911) Printing (from Lat. imprimere, O. Fr. empreindre), the art or practice of transferring by pressure, letters, characters or designs upon paper or other impressible surfaces, usually by means of ink or oily pigment. As thus defined, it includes three entirely different processes: copperplate printing, lithographic or chemical stone-printing, and letterpress printing. The difference between the three lies in the nature or conformation of the surface which is covered with the pigment and afterwards gives a reproduction in reverse on the material impressed. For the nature and method of preparing these surfaces see respectively Engraving (and allied articles), Lithography and Typography. In copperplate printing the whole of the plate is first inked, the flat surface is then cleaned, leaving ink in the incisions or trenches cut by the engraver, so that, when dampened paper is laid over the plate and pressure is brought to bear, the paper sinks into the incisions and takes up the ink, which makes an impression in line or lines on the paper. In lithographic printing the surface of the stone, which is practically level, is protected by dampening against taking the ink except where the design requires. In letterpress printing the printing surface is in relief, and alone receives the ink, the remainder being protected by its lower level. Before the invention of typography, pages of books, or anything of a broadside nature, were printed from woodcuts, i.e. blocks cut with a knife on wood plankwise, as distinct from wood engravings which are cut with a burin on the end grain, a more modern innovation. These woodcuts, like the lithographic or engraved surface, served one definite purpose only, but in typography the types can be distributed and used again in other combinations.
The term " printing " is often used to include all the various processes that go to make the finished product; but in this article it is properly confined to " press-work," i.e. to the work of the printing-press, by which the book, newspaper, or other printed article, when set up in type and ready as a surface to be actually impressed on the paper, is finally converted into the shape in which it is to be issued or published.
History of Printing-press. Before dealing with modern machinery it will be necessary to consider the historical evolution of the printing-press, especially since the middle of the 19th century, from which point printing machinery has developed in a most remarkable manner.
It is not clear how the first printers struck off their copies, but without doubt Gutenberg did use at an early period in his career a mechanical press of some kind, which was constructed of wood. In fact he could not have produced his famous forty-two line Bible without such aid.
The earliest picture of a press shows roughly the construction to have been that of an upright frame, the power exerted by a movable handle, placed in a screw which was tightened up to secure the requisite impression, and was loosened again after the impression was obtained. The type pages were placed on a fiat bed of solid wood or stone, and it was quite a labour to run this bed into its proper position FIG. i. - Blaeu's Wooden Hand-press.
under the hanging but fixed horizontal plane, called the platen, which gave the necessary impress when screwed down by the aid of the movable bar. This labour had to be repeated in order to release the printed sheet and before another copy could be struck off. This same press, with a few modifications, was apparently still in general use till the early part of the 17th century, when Willem Janszon Blaeu (1J71-1638) of Amsterdam, who was appointed map maker to the Dutch Republic in 1633, made some substantial improvements in it. Our first authority on printing, Joseph Moxon, in his Mechanick Exercises, as Applied to the Art of Printing (vol. i., 168 3), says, " There are two sorts of presses in use, viz. the old fashion and the new fashion," and he gives credit to Blaeu for the invention of the new and decidedly improved press (fig. 1).
Blaeu's improvement consisted of putting the spindle of the screw through a square block which was guided in the wooden frame, and from this block the platen was suspended by wires or cords. This block gave a more rigid platen, and at the same time ensured a more equal motion to the screw when actuated by the bar-handle. He also invented a device which allowed the bed on which the type pages were placed to run in and out more readily, thus reducing the great labour involved in that part of the work of the older form of press, and he also used a new kind of iron lever or handle to turn the screw which applied the necessary pressure. The value of these various improvements, which were in details rather than in principles, was speedily recognized, and the press was introduced into England and became known as the " new fashion." From this it will be observed that in a general way there had only been two kinds of wooden presses in use for a period of no less than three hundred and fifty years, and when the work of some of the early printers is studied, it is marvellous how often good results were obtained from such crude appliances.
The iron press (fig. 2) invented by Charles, 3rd earl Stanhope (1753-1816), at the end of the 18th century was a decided advance on those made of wood. Greater power was obtained at a smaller expenditure of labour, and it allowed of larger and heavier surfaces being printed. The chief points of the iron press consisted of an improved application of the power to the spindle. The main part of it was FIG. 2. - The Stanhope Iron Hand-press.
complete press to stand upon. The staple was united at the top and bottom, but the neck and body were left open, the former for the mechanism and the latter for the platen and the bed when run in preparatory to taking the impression. The upper part of the staple, called the nut, answered the same purpose as the head in the older kind of wooden press, and was in fact a box with a female screw in which the screw of the spindle worked. The lower portion of the neck was occupied by a piston and cup, in and on which the toe of the spindle worked. On the near side of the staple was a vertical pillar, termed the arbor, the lower end of which was inserted into the staple at the top of the shoulder - the upper end passing through a top-plate, which being screwed on to the upper part of the staple held it firmly. The extreme upper end of the arbor, which was hexagonal, received a head, which was really a lever of some length; this head was connected by a coupling-bar to a similar lever or head, into which the upper end of the spindle was inserted. The bar by which the power was applied by the pressman was fixed into the arbor, and not into the spindle, so that the lever was the whole width of the press, instead of half, as in Blaeu's wooden press, and it was better placed for the application of the worker's strength. There was also another lever to the arbor head in addition to that of the spindle head; and lastly, the screw itself was so enlarged that it greatly increased the power. The platen was screwed on to the under surface of the spindle; the table or bed had slides underneath which moved in, and not on, ribs as in the older form of press, and was run in and out by means of strips of webbing fastened to each end and passed round a drum or wheel. As the platen was very heavy the operator was assisted in raising it from the type-forme by a balance weight suspended upon a hooked lever at the back of the press. This somewhat counterbalanced the weight of the platen, raised it after the impression had been taken, and brought the barhandle back again to its original position, ready for another pull.
The Stanhope press, which is still in use, was soon followed by other hand-presses made of iron, with varying changes of details. The most successful of these were the Albion and Columbian presses, the former of English manufacture, and the latter invented (1816) by an American, George Clymer (1754-1834), of Philadelphia.
The Albion press (fig. 3), which was designed by Richard Whittaker Cope, was afterwards much improved upon by John Hopkinson (1849-1898). It is still used where hand printing prevails, and it was this form of press which was employed by William Morris at his famous, but short-lived, Kelmscott Press, the upright frame or staple, of iron; the feet of this staple rested upon two pieces of substantial timber dovetailed into a cross, which formed a base or foundation for the in the production of many sumptuous books, the most celebrated of which was the Chaucer, a large folio volume, illustrated by Sir Edward Burne-Jones. The chief characteristics of the Albion are its lightness of build and its ease in running; the pull is short, the power great, and the means whereby it is attained so simple that the press does not readily get out of order. It is easily taken to pieces for cleaning, and readily re-erected. The power is obtained by pulling the bar-handle across, which causes FIG. 3. - Payne & Sons' Albion Hand-press.
an inclined piece of wedge-shaped steel, called the chill, to become perpendicular; in so doing the platen is forced down, and the impression takes place at the moment the chill is brought into a vertical position. On the return of the bar the platen is raised by a spiral spring, placed in a box and fixed at the head of the press. The larger sizes of these presses usually print a sheet of double crown, measuring 30X20 in.
Although the Columbian is not so much in demand as the Albion, it is still employed for heavy hand-work because of its greater stability and power. This power is acquired by a very massive lever, moving on a pivot bolt in the top of the near side of the staple, and passing across the press to the further side of the frame, at which end the power is applied through the coupling-bar by a bar-handle working from the near side. The platen is attached to the centre of the lever by a square bar of iron, and its vertical descent is assured by two projecting guides, one from each cheek; it is then raised from the type-forme, and the iron bar carried back by two levers - the one attached to and above the head and weighted with the eagle; the other behind the press, attached to the arm to which the coupling-bar is fixed, and which also has a weight at the end. The great power of this press adapts it to the working of large and solid formes in printing, but it is somewhat slower in action than the Albion press, which is both lighter in construction and quicker in working.
The average output of the modern hand-press, when all is made ready for running, is about two hundred and fifty impressions per hour. This number, it should be said, is the product of two men who work together as " partners." One inks the type-forme and keeps a sharp look-out for any inequality of inking, and sees generally that the work is being turned out in a workmanlike manner. The other lays on the sheet to certain marks, runs the carriage in under the platen, and pulls the barhandle across to give the necessary impression. He then runs back the carriage and takes out the printed sheet, which he replaces by another sheet, and repeats the different operations for the next impression. During the interval between taking off the printed sheet and laying on the next one his partner inks the type surface with a roller which carries just sufficient ink properly distributed to preserve uniformity of " colour." Having dealt with hand-presses, we must now go back to the end of the 18th century, when the first experiments were made to devise some mechanical means of producing larger printed sheets, and at a quicker rate. In England the broad distinction between " presses " and " machines " is generally considered to rest in the fact that the former are worked by hand, and the latter by steam, gas or electricity; and the men who work by these two methods are called respectively " pressmen " and " machine minders " or " machine managers." But in America the terms " presses " and " pressmen " are universally applied to machines and the men who operate them. For the purposes of this article presses and machines are used as synonymous terms.
Various schemes had been propounded with a view of increasing the output of the hand-press, and in 1790 William Nicholson (1753-1815) evolved his ideas on the subject, which were suggestions rather than definite Cylinder inventions. Nicholson was not a printer, but, as he was an author and editor, it is presumed that he had some knowledge of printing. His proposals were to print from type placed either on a flat bed or a cylinder, and the impression was to be given by another cylinder covered with some suitable material, the paper being fed in between the type and the impression cylinder, and the ink applied by rollers covered with cloth or leather, or both. While Nicholson's schemes did not bear any practical result they certainly helped others later on. His suggestion to print from type made wedge-shaped (that is, smaller at the foot and wider at the top) to allow of its being so fixed on a cylinder that it would radiate from the centre and thus present an even printing surface, was adopted later by Applegath and others, and really was the first conception of printing on the rotary principle which has now been brought to such perfection.
It was left to Friedrich Ktinig (1774-1833), a German, to produce the first really practical printing machine. His invention was to print type placed on a flat bed, the impression being given by a large cylinder, under which the type passed, but his inking appliances were not satisfactory. He induced the proprietor of The Times (London) to take two of these machines, and in 1814 that newspaper was printed with steam power at the rate of i roo impressions per hour, a great advance on the number produced up to that time. Both Nicholson's and Kijnig's machines printed only one side at a time - the second or backing printing being a separate and distinct operation - but they really embodied the general principles on which all other machines have been constructed or modelled.
It will be understood that Nicholson's theories were to print both from the flat and from type arranged in circular or cylinder form. These two principles are defined as reciprocating, for the flat bed which travels backwards and forwards; and rotary, for that which continuously revolves or rotates. Konig's invention was a reciprocating one.
Two other classes of presses of somewhat different design were largely in operation in the middle of the r9th century - the " double platen," which still printed only one side at each impression from each end, and the " perfecting machine," which was made with two large cylinders and printed from two typeformes placed on separate beds. Although the latter machine turned out sheets printed on both sides before it delivered them (hence its name), the second impression was still a distinct operation. The double platen press was somewhat analogous to the hand-press, both the type beds and impressions being flat. A machine of this kind, if it printed a sheet of double demy, which measures 35 X 221 in., was about 13 ft. in length, and the platen itself, of very massive construction, was placed in the centre. This platen had a perpendicular motion, being guided in grooves and worked by a connecting rod fixed to a cross beam and crank, which acquired its motion from the main shaft. There were two type beds and two inking tables, which travelled backwards and forwards, and one platen only, situated in the middle of the machine, which in turn gave the needful impression as the type-formes passed underneath. The sheets were laid or fed to certain marks between the frisket and tympan, and when these were closed together the carriage was propelled under the platen and the impression was given to that portion of the machine, while at the other end another sheet was being fed in ready to receive its impression in due course.
It was once thought that the finest work could not be produced by a cylinder impressing a surface in the progress of its reciprocating motion, but that it was likely to give a slurred or blurred impression. This is why machines of flat construction were so long employed for the best class of work. But cylinder presses are now made so truly turned, and geared to such nicety, that this idea no longer prevails. The cylinder press is able to produce generally quite as good work as the double platen, its speed is much greater, and it requires a smaller amount of power to drive it.
The perfecting machine has had a great vogue, and has been much improved from time to time, especially in America, though the two-revolution machine in recent years superseded it, whether temporarily or not being still uncertain. We shall deal with it more fully below in relation to the modern and more complicated class of machinery; and this also applies to the ordinary stop or single cylinder, and small platen machines, both of which have been in use many years, and are still in demand.
Before the general introduction of rotary machines which print from curved stereotype plates from an endless web or reel Type of paper (see below), several other presses of a revol- Revolving ving character were made, to some extent based on Nicholson's ideas. The first printing surface used was ordinary type, because the difficulty of curving the stereotype plates had not been surmounted. This type was fixed, both in vertical and in perpendicular positions, upon a cylinder, round which rotated other cylinders, which held and compressed the sheets against the larger one, which also revolved and carried the printing surface. These machines were made to print several sheets at a time, and were called four-, six-, eightor ten-feeders, according to the number of sheets fed in and printed. They necessitated a great deal of labour, because each feed required a separate layer-on and taker-off besides the superintending printer, and other hands to carry away the sheets as fast as they accumulated at the different taking-off boards. Besides, these sheets all had to be folded by hand. In this class of machine various improvements were made from time to time by different manufacturers, each profiting by the experiences of the others, and two kinds of such revolving presses may now be given as examples.
After many experiments Augustus Applegath (1789-1871) in 1848 constructed for The Times (London), a machine which was an eight-feeder, built entirely on the cylindrical principle, the cylinders placed not in a horizontal but in a vertical position. The type was fixed on a large cylinder, and instead of the printing surface presenting a complete circle, the different columns were each arranged so as to form a polygon. Around this large type cylinder were eight smaller ones, all upright, for taking the impression for each of the eight sheets fed in separately, and rollers were so arranged as to apply the ink to the type as it passed alternately from one impression cylinder to the other. The sheets were laid in from eight different feed-boards, placed horizontally, and they passed through tapes, when they were seized by another series of tapes and then turned sideways between their corresponding impression and type cylinder, thus obtaining sheets printed on one side only. The impression cylinder then delivered the sheets separately (still in a vertical position) into the hands of the boys employed as takers-off. The results from this press were, at the time, considered fairly satisfactory, the number of copies (about 8000) printed per hour from one type-forme having been materially increased by the employing of the eight different stations to feed the sheets in, all of which in turn were printed from the same single type surface.
About 1845 Robert Hoe & Co. of New York, and subsequently of London, had constructed, to meet the increased demands of newspapers, the " Hoe Type Revolving Machine," one good point of which was an apparatus for securely fastening in the type on a large central cylinder fixed horizontally. This was accomplished by the construction of cast-iron beds, one for each separate page (not column, as in Applegath's machine). The column rules were made tapering towards the feet of the type, and the type was securely locked in on these beds so that it could be held firmly in the required position to form a complete circle, thus allowing the cylinder to revolve at a greater speed than Applegath's, which was polygonal. Around the large type cylinders were placed the smaller impression cylinders, the number of these being governed by the output required. Hoe's first presses were four-feeders, but as many as ten feeds were supplied, as in the case of the two presses built to replace the Applegath machine for The Times, each of which produced about 2000 impressions from each feed, making a total of 20,000 per hour, printed on one side, or from two machines 20,000 sheets printed on both sides. As will be observed, the only differences in principle between these two type revolving machines were in the positions of the respective cylinders, and the fixing of the type to form a printing surface.
It was Sir Rowland Hill who first suggested the possibilities of a press which should print both sides at once, from a roll or reel of paper. This was about 1825, but it was William A. Bullock (1813-1867) of Philadelphia who in 1865 invented the first machine to print from a continuous web of paper. This machine had two pairs of cylinders, that is, two type or stereotype cylinders, and two others which gave the impression as the web passed between. The second impression cylinder was made somewhat larger so as to give a greater tympan surface, to lessen the off-set from the side first printed. In his machine the stereotype plates were not made to fill the whole periphery of the forme cylinders so as to allow of the sheets being cut before printing, a difficulty w'iich the first machines did not satisfactorily overcome. The sheets were severed by knives placed on the cylinders, and when cut were carried by grippers and tapes; and delivery was made by means of automatic metal fingers fixed upon endless belts at such distances apart as to seize each sheet in succession as it left the last printing cylinder. These presses were not at first reliable in working, especially in the cutting and delivery of the sheets after printing, but were finally so far improved that the Bullock press came into quite general use. The inventor was killed by being caught in the driving belt of one of his own presses.
Modern Presses. The machines invented during the second half of the 19th century and still in general use, are best classified as follows: - I. The iron hand-press, such as the Albion or the Columbian, used for the pulling of proofs, or for the printing of limited editions de luxe. 2. Small platen machines (worked by foot or tion power) used for the printing of cards, circulars and small jobbing or commercial work.
3. Single cylinder machines (in England generally called " Wharfedales "), usually built on the " stop " cylinder principle, and printing one side of the sheet only.
4. Perfecting machines, usually with two cylinders, and printing or " perfecting " both sides of a sheet before it leaves the machine, but with two distinct operations.
5. Two-revolution machines, which, although with but one cylinder, have largely superseded perfecting machines, as their output has been increased and the quality of their work compares favourably with that of the average two-cylinder.
6. Two-colour machines, usually made with one feed, that is, with only one cylinder, but with two printing surfaces, and two sets of inking apparatus one at each end of the machine. Occasionally these machines are made with two cylinders.
7. Rotary machines, printing from an endless web of paper from curved stereotype or electrotype plates, principally used XXII. 12 for newspaper or periodical work. They are made to print upon a single reel, or upon two, four, six or even eight reels, in both single or double widths, i.e. two or four pages wide.
The hand-press has already been sufficiently described, and we may proceed to deal with the other classes.
The small but useful platen machine (fig. 4) is very largely employed in those printing-houses that make commercial work a speciality. The smaller machines can be worked with the foot, but if the establishment is equipped with power it is customary to gear them for driving. The larger machines require power. As its name implies, the type bed and impression platen are both flat surfaces as in the hand-press, but as they are self-inking and are easily driven, the average output is about moo copies per hour, and but one operator is required, whereas two men at a handpress can produce only 250 copies in the same time. In design these platen presses usually consist of a square frame with a driving shaft fixed horizontally across the centre of it. This shaft is attached to a large fly-wheel which gives impetus to the press when started and assists in carrying over the impression when the platen is in contact with the printing surface. The type-forme is usually fixed in an almost vertical and stationary position, and it is the platen on which the sheet is laid which rises from the horizontal position to the vertical in order to give the necessary impact to produce a printed impression from the typeforme. Practically this platen is, as it were, hinged at the off side, nearest the type bed, and its rise and fall is effected by the use of FIG. 4. - The Golding Jobber Platen two arms, one on each side Machi, of the platen, which derive ne an eccentric motion from cams geared in connexion with the shaft. When the sheet is printed and the platen falls back to the horizontal the operator removes it with one hand and with the other lays on a fresh sheet. Generally the larger of these machines will print a sheet up to 21 X 16 in.
The modern single or " stop " cylinder, quite different in construc- Wharfe= tion from the old single cylinder machines, largely suc dale" ceeded the double platen machine. The principle of the cl . stop cylinder was really a French invention, but it has Machines been more commonly adopted in Great Britain, where the machines are known as " Wharfedales " (fig. 5). They are much used for the printing of books and commercial work. The average production is about woo copies per hour. The type bed travels with a reciprocating motion upon rollers or runners made of steel, the bed being driven by a simple crank motion, starting and stopping without much noise or vibration. All the running parts are made of hard steel. The cylinder is " stopped " by a cam motion while the bed is travelling backward, and during this interval the sheet to be printed is laid against the " marks," and the gripper closes on it before the cylinder is released, thus ensuring great accuracy of lay, and consequent good register. After the impression is made the sheet is seized by another set of fingers and is transferred to a second and smaller cylinder over the larger one, and this smaller cylinder or drum delivers the sheet to the " flyer," or delivery apparatus, which in turn deposits it upon the table. The inking arrangements are usually very good, for, by a system of racks and cogs which may be regulated to a nicety, the necessary distribution of ink and rolling of the printing surface runs in gear with the travelling type bed or coffin. All the accessories for inking are placed at the end of the machine, the ink itself being supplied from a ductor, which can be so regulated by the keys attached to it as to let out the precise amount of pigment required. The ink passes to a small solid metal roller, and is then conveyed by a vibrating roller made of composition to a larger and hollow metal cylinder or drum which distributes the ink for the first time. This revolves with the run of the machine and at the same time has a slight reciprocating action which helps the distribution. A second vibrating composition roller conveys the ink from this drum to the distributing table or ink slab, on which other rollers, called distributors, still further thin out the ink. As the type bed travels, larger composition rollers, called inkers, placed near the cylinder, adjusted to the requisite pressure on the type, pick up the necessary amount of ink for each impression and convey it to the type as it passes under them. Usually three or four such rollers are required to ink the forme.
The perfecting machine is so named because it produces sheets printed on both sides or, in technical language, " perfected." This operation is performed by two distinct printings. This perfecting class of machine has been in use a great many years, Machines. although both the stop-cylinder and the two-revolution press have to some extent superseded it. It is perhaps best adapted for the printing of newspapers or magazines having circulations that do not require rotary machines intended for long runs. Although some perfecting machines have been made with one cylinder only, which reverses itself on the old " tumbler " principle, they now are made with two cylinders, and it is with this class that we are particularly concerned. There are various makes of perfecting machines of which the Dryden & Foord is shown in fig. 6; among the best recent typed is the Huber Perfecter.
Although the two-type beds have a reciprocating motion, as in the ordinary one-sided press, the two cylinders rotate towards each other. The frame of the machine, owing to the fact that it contains two carriages and a double inking apparatus, is long, the exact size depending on the size of the sheet to be printed. Close to the large cylinders are the inking rollers, which take the necessary amount of ink, each set from its own slab as it passes under, and these rollers convey the requisite ink to the printing surface as the forme-carriage runs under its own cylinder. The distinctive feature is the ingenious manner in which the sheets are printed first on one side, and then on the other. This is performed by carrying them over a series of smaller cylinders or drums by means of tapes. The pile of sheets ?
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