Lithography

li-thog'ra-fy, the art of preparing a stone surface and of printing from it. Limestone of a close, marble-like texture is used for the purpose. It must be free from defects, such as veins or chalk spots. The best lithographer's stone is quarried in a certain ten-acre field at Solenhofen, Bavaria. It varies in color from a light cream to blue-gray. It is quarried in large blocks, which are sawed into slabs of suitable size. It is sold by the pound. The larger a perfect slab, the more it is worth per pound. The price varies from two or three cents to fifty cents a pound. Stone somewhat inferior in quality is found in France and England. A supply has been found in Texas. This is so crossed by faults, however, that only slabs of small size can be secured. Quarries are also to be found in Virginia, Indiana, and Arkansas. A company has been formed recently to work a quarry near Osage, Iowa. The Solenhofen dealers ship $100,000 worth to the United States yearly. To save freight the stone is faced on both sides. Bremen is the port of export.

In use, the surface of a slab is polished to a perfect plane; the design is then drawn by the artist with a crayon composed of beeswax, tallow, shellac, mastic, turpentine, soap, and lampblack. Instead of a crayon picture, a pen sketch may be drawn in ink, composed of the same materials. The sketched surface of the stone is then treated with a solution of gum arabic and nitric acid. This acts chemically on the uncovered portions of the stone and forms a water-like film that rejects grease. It has no action on the crayon sketch. The stone may then be placed in a printing press like a form of type. When the roller covered with printer's ink of the desired color is passed over the surface of the stone, the ink adheres to the sketch only. The remaining portions of the stone take off no ink whatever. When a sheet of paper is laid on the stone and subjected to pressure and then removed, it bears, of course, a perfect impression of the original crayon sketch. Such a printed sheet is called a lithograph. There is no difference in the level of the different parts of the face of the stone. The sketch and the colorless portion are in the same plane. In this respect lithographing is entirely different from etching, engraving, and printing.

If a lithograph in more than one color is desired, it must be printed on more than one stone. Two impressions may be made to give a lithograph in three colors, as the portions where they overlap will be of a color different from either of the originals. A design printed in red ink, and a design printed in blue ink, by overlapping in part, may be made to produce a lithograph in red, violet, and blue, with but two impressions. Three stones and three impressions may be made to produce a lithograph in six colors and so on. The artist is obliged to remember, of course, that a left-handed design on the stone produces a right-handed picture, and the reverse.

The art of lithographing was suggested to a German by the name of Senefelder, who sought some means of improving etching and copper engraving. He hit upon the idea of printing from stone about the year 1798. In 1806 he settled at Munich, a city which is still noted among lithographers. No important changes have been made in his methods.

Many attempts have been made to find a substitute for stone. Copper, steel, and zinc have been tried without satisfactory results. Of late, aluminum sheets have been found to be almost as satisfactory as stone. They have also the advantage of permitting curvature, so that they may be fitted to cylinder presses. It is estimated that in the United States about 13,000 people are employed in lithographing, and that they produce lithographs to the value of about $20,000,000 a year.

At the risk of extending this article unduly the following account is taken from the report (1909) of Consul General H. W. Harris. It is an instructive sketch of an industry, the importance of which far exceeds the capital involved:

The quarrying and preparing for market of lithographic stones is a unique industry of this consular district, carried on near Solenhofen, about forty-five miles south of Nuremberg, on the main railway line to Munich. The town is an unimportant one of about 1,300 inhabitants, the stone quarries being in the hills back of the town at a level of some 1,500 feet above the sea.

So far as is now known, the area in which these stones are found is not more than four or five miles long by two or three miles wide. In this limited area quarrying has been carried on for more than a century, and from it practically the world's supply of lithographic stones has been obtained.

The stone, as is well known, is a species of compact limestone of peculiar texture and of a yellowish-gray or bluish-gray color, hard bluish stones being the more valuable. It is found in layers varying in thickness from a half inch, or even less, up to six or seven inches. The layers extend from near the surface of the ground to a depth of seventy-five or 100 feet, or even more, and are apt to be much broken by fractures or seams and layers of worthless rock and earth.

In the best quarries not more than one-twelfth of the material removed is marketable stone, and much of this is of little value because of the small sizes in which it can be found clear of cracks or flaws. The quarrying is carried on by several different firms and by a corporation. About 1,200 workmen are employed in the various quarries and in the work of cutting and dressing the stone for market. The stones are lifted carefully from their position in the quarries in various marketable sizes and are then hauled to buildings near by. Here the surfaces--for some markets one and for others both--are ground down, chiefly with coarse sand rubbed on by heavy machines, water being constantly applied during the process.

One concern has recently introduced a heavy machine fitted with a carborundum planer, which rapidly smooths the surface of the stones as they are passed back and forth under the planer, somewhat as heavy plank in a planing mill. The stones are further smoothed by machinery and by hand, the edges being neatly trimmed and corners rounded.

If the stones are six inches or seven inches thick when taken from the quarries, as is sometimes the case, they are sawed through once by heavy saws fitted on the edges with diamonds and operated by steam power. The finished stones vary in size from 6 by 8 inches to 44 by 64 inches, and vary in price, when ready for shipment, from fifteen or twenty cents up to $65 or $70, depending upon the size and quality. In recent years the thinner stones, which would break under the pressure to which they are subjected in printing, are, in some cases, securely cemented to other stone slabs, thus giving the requisite strength.

It is a notable fact that the industry has never been a source of great profit to those engaged in it. The explanation is that the amount of dead work in the quarries is large, and the proportion of perfect stone of marketable size so small as to leave little margin of profit at the prices at which the stones are sold. It frequently happens that after a stone has been ground smooth, or perhaps been sawed through at considerable expense, a chalky vein, small pebbles, or other defects appear in the surface, greatly lessening its value. These defects become apparent only when a damp sponge is passed over the surface of the stone.

It would appear that the demand for this stone has not increased rapidly of late. The American demand has grown from $105,949 worth in 1900 to $161,905 in 1907. The stones are shipped to all civilized countries. Germany is the heaviest buyer, then come France, Italy, England, and the United States. At the present rate of quarrying, the supply will last for a century or two.

See Engraving; Etching; Printing