Litho-typography

The peculiarities of cylindrical printing have been successfully applied to the purchases of lithography, and made to take impressions of ligures from the Hat surface of a stone with almost the ease and certainty, and with nearly the same rapidity, as it is able to produce copies from the raised surfaces of ordinary type. The ordinary rate of letter-press printing, by two pressmen, is a token, or 250 copies, per hour; but, slow as this may seem, it is express speed in comparison with the dawdling manual process of producing lithographic impressions; since a letter-press printer at half -press accomplishes at least his 1200 copies in a day, whereas a lithographic pressman can work off but thirty to forty prints an hour, and this is at the rate of only 300 to 400 per diem. The reason of this vast difference between the speed of the two kindred operations is, that not only are the distinct processes which have to be carried out, in order to produce a single copy by lithography greater in number than those which have to be gone through in typography, but they are each of a more delicate character, and consequently require greater care and time in the prosecution of them.

The several operations which have to be gone through each time a lithographic print is produced are as follows:—

1. Inking the roller.
2. Damping the stone.
3. Inking the stone.
4. Laying the sheet on the stone.
5. Lowering the tympan.
6. Running in the stone.
7. Depressing the scraper of the press, by means of the side lever.
8. Passing the stone under the scraper.
9. Lifting the scraper.
10. Running out the stone.
11. Lifting the tympan.
12. Removing the printed sheet.

But as the invention of the typographic machine more than quadrupled, in the first instance, the ordinary rate of production by hand, and did so merely by reducing the nine distinct operations involved in the letter-press printing to three, so the introduction of the lithographic machine has increased the speed with which impressions can be obtained nearly twentyfold—the machine producing as many as 700 copies an hour, instead of only 300 or 400 a day, as by hand.

The acceleration, too, has been gained partly in the same manner as the quickening of the process was effected by the first printing machine, namely, by reducing the twelve distinct operations requisite to be performed in printing lithography manually to only three, and this either by the omission of some of them, or the combination of others, so that two or more are executed simultaneously by the apparatus of the machine, rather than successively, as in the hand process.

Every lithographic machine is made up of five distinct forms of apparatus:—

1. The damping apparatus.
2. The inking apparatus.
3. The “feeding” apparatus.
4. The impression apparatus.
5. The delivery apparatus.

Thus it will be seen that machines for lithographic purposes are composed of the same mechanical adaptations as the typographical ones, with the addition of the appliances requisite for damping the stone. But though a perfect lithographic machine requires as many as five different self-acting contrivances (some have only four, the stone being damped by hand), nevertheless, in the production of the impressions there are only three distinct operations automatically performed—the stone being damped, the roller inked, and the ink applied to the surface, as well as the impression given, with each alternate traverse of the table, as is the case, with the exception of the damping, during the reciprocating movement of the ordinary typographic machines.

Hence the lowering and lifting of the tympan are both done away with, as well as the depression and after elevation of the scraper, so that four out of the twelve successive operations are dispensed with; whilst the inking the roller, damping the stone, and inking the stone, as well as running it in and taking the impression, and then running it out again, are, as we have said, made to constitute but one act performed by the simple traverse of the impression table.

Hence, as the laying-on of the sheet and removing the print have each to be performed in both the mechanical and manual processes, the entire dozen operations are abridged to three, and the gain thus rendered four-fold; so that, allowing the machine to work five times as quick as a man, we can readily perceive that the rate of production mechanically must be twenty times more than it is manually. By means of the platen of the old printing-press the pressure applied to the type was perfectly flat and simultaneous—all the parts of the forme being impinged upon together, rather than successively, as in cylindrical printing; but raised surfaces alone can be printed platen-wise. It would be impossible to force the sheet to take up the ink out of the fine crevices made in a copper or steel plate engraving, or, indeed, from any device in intaglio, by means- of a flat pressure given to every part of the surface at once.

Hence, for copper-plate printing, a cylinder has to be used in order to obtain the impression; for the pressure of this, when coated with a semi-elastic substance like blanketing, is of so searching a character, that it forces itself down into the several hollows of the surface, both as it comes to and leaves each part over which it has successively to pass—the very successiveness of the pressure serving to produce the impression. Nor could the delineation upon the flat surface of a lithographic stone be successively taken off by such flat and simultaneous pressure. In lithographic printing, the force has to be successively applied, as in the case of copper -plate work; but it was generally believed that, unlike that mode of obtaining impressions from the incisions or sunk parts of surfaces, it was necessary, owing to lithography being executed on a flat surface, that a certain amount of friction should be applied, evenly and gradually, to every part of the stone, one after the other, in order to obtain the impression with all the beauty and fineness of the original.

Hence the scraper was always made a constituent, and for a long time was considered to be an essential portion of the process, the action of such an instrument being not only to produce successive vertical pressure, but a certain amount of friction in a horizontal direction. And it was this common fallacy as to the necessity of some such instrument being used in order to obtain perfect lithographic impressions, which formed the great impediment in the advance of steam lithographic machinery.

That such a prejudice is utterly erroneous, the cylindrical machines lately constructed have demonstrated in the most practical manner, the impressions being admitted by the best printers to be fully as fine and sharp in every part as any that have been produced by means of the scraper. Indeed, it must be self-evident to all in the least acquainted with mathematics, that as a cylinder can only impinge upon a plain surface in a line, even as a circle can but touch such a line in a point, that the lithographic stone, as it passes under the impression cylinder of the machine, must have the same linear impression successively given to every part of the device delineated upon it, and that this must consequently become impressed upon the paper between it and the cylinder in the same manner as if the common lithographic hand-press had been used for the purpose; but, with the all-important exception, that little or no friction has been applied in order to obtain it. It is true, that as the impression cylinder of the litho-machine is continually revolving, the stone, while passing under it, receives a vertical, linear, and instantaneous impression upon each part of it successively, rather than a continually sliding horizontal one, such as is produced by the action of the scraper.

Nevertheless, the lines, however finely drawn upon the stone, are, by the cylindrical method of printing, just as finely impressed upon the sheet; but at the same time, the friction, which was long thought necessary for the purpose, is to a great extent done away with: and the consequence is that the device on the stone remains for a much longer period uninjured.

Indeed, the litho machine, owing to the cylinder exerting a less amount of exertion than the scraper on the surface, is capable of producing a far greater number of impressions from the same delineation than can be obtained by the hand-press. Indeed, the old frictional or forcible sliding method of producing impressions from lithography by means of the scrai)er formed in no way an essential part of the process; and that, instead of adding to the beauty of the impression, it was, owing to this friction which was thought necessary to produce it, continually destroying the fineness of the lines to which it was applied, and thus rendering the more delicate delineations on the stone of a less durable character.

In fact, in the course of the experiments which were made in fitting up the lithographic machine, it was found that wherever the friction occurred—as, for instance, at those parts where the cylinder met the stone or left it—the lines were more or less injured, and that unless the cylinder were made to “bear up” at these points, fewer impressions could be taken without their betraying signs of rottenness at the upper or lower parts of the delineation—and this, whilst the finest lines in the middle portions of the subject remained absolutely unbroken.

Thus it has been experimentally demonstrated that, in the old method of obtaining impressions from lithography by means of the scraper, the horizontal friction, so far from being of service in the process, was really a serious drawback to it; and that the successive vertical pressure exerted by this part of the lithographic press was all that was needed—the continual scraping of the surface of the stone tending, on the other hand, gradually to destroy the sharpness of the impression, and proportionately to reduce the number of copies which would be yielded by it. But by the cylindrical method of printing, on the contrary, the successive vertical pressure being retained, and the horizontal friction removed, a far greater number of prints could be produced from the one delineation; and this merely because, owing to there being little or no friction upon the lines drawn upon the stone, such a mode of printing serves to keep them in their original integrity, and thus enables them to yield at least double or treble the number of copies which could be obtained by the old frictional method.

The first successful lithographic machine was introduced about twenty years since. This, as was the case with the typographic machine, was the invention of a German—one named Siegel, and it is now in use.* The manufacture of lithographic machines is now an important business in London. There is very little variety in the construction of the different makers’ machines.