Lithography as an art reached its climax in Paris during the reign of Louis Philippe. Among the masters who distinguished them selves were the satirists Daumier, Grandville, Travies and Gavarni, Deveria, Delacroix, Johannot and Gigoux, the delineators of ro mantic literature; Charlet, and Raffet, who found material in the glorification of Na poleon's career. Other painter-lithographers of the day were Gericault, Richard Park Boning ton, James Duffield Harding, Eugene Isabey, Alexandre Calame and Julien, whose (Etudes en Deux Crayons" made him famous. Since the introduction of the power-press and the consequent development of the lithographic in dustry as a commercial factor, the medium of lithography has found less favor as a mode of individual artistic expression. Commercially it has grown to be one of the most important brandies of the printer's craft. The Depart ment of Commerce, census of manufactures for 1914, published in 1917, gives the number of establishments 336, employees 15,171, invested capital $36,685,000, and value of annual product 125,119,000.
Materials.— The stone used, known as stone,* is a compact, homogeneous limestone of porous texture and varies in color from light cream, dull yellow, drab or gray to darker shades of the same colors, the best being found among the light gray varieties. The darker the color the harder the stone. Litho graphic stone is quarried chiefly at Solenhofen, Germany, from beds of Jurassic Age, and while similar stone has been found in England, France and America, none possess the quality of the Solenhofen product. The most satisfactory American product is said to come from Bran denburg, Ky. It is sawn at the quarries into slabs of from three to five inches in thick ness, varying in size from 6 X 8 inches to 44 X 64 inches and is sold by weight. The price per pound being based on quality and size, the very large stones when free from blemishes such as veins and chalk spots are the most expensive and very scarce. Owing to the expense in curred in handling and storing the cumbersome stone, a substitute embodying the same prop erties has been the desideratum of lithographers almost since the invention of surface printing. Zinc has been in use for 50 years or more, but up to 10 years ago was used only for very ordinary work. Since that time it has come into considerabe use for offset lithography (de scribed later). Aluminum has been satisfac torily used as a substitute for stone for about 20 years and for some purposes is preferable to zinc as a substitute.
Lithographic crayon is composed of beeswax, shellac, tallow, mastic turpentine, soap and lampblack in several degrees of hardness.
Lithographic ink adapted for pen work on stone contains the same ingredients as the crayon, with a larger quantity of the soap, in order to make it soluble in water. The ink is furnished in sticks and rubbed over a plate or saucer and then gradually dissolved with water or turpentine until it becomes fluid. Gum arabic and acids are important factors in li thography; in fact, Senefelder's original inven tion would have proven of little practical value had he not also discovered the use of these in reinforcing the qualities of the stone.
Process.— The stone is first leveled and if desired for crayon work the surface is grained by grinding with fine sand and water between two slabs of stone until its surface has a grain similar to the grain on fine drawing paper. For pen or stipple work the stone is polished with pumice or scotch stone. The drawing is made on the stone in the same manner as if it were drawn on paper, except that the design is reversed. Considerable experience is required by the artist to obtain proficiency in rendering a reverse facsimile of the original. In the hands of a capable artist no reproductive art can offer greater possibility than that of crayon on a grained stone. It permits greater freedom as compared with steel, copper plate or wood engraving, inasmuch as technique is less im portant than true artisticability, while an infinite variety of tones, from the most delicate shade to rich, deep black, lies within its possibilities.
Somewhat more mechanical is the pen stipple manner, and which as its name implies consists of drawing with small dots, the relative values of shading being determined by the varying density of the dots. This manner is employed mainly in chromo-lithography, its chief recom mendation being the clean, sharp, solid nature of the work.
When the drawing is completed, its sur face is treated with a solution of gum arabic and nitric acid, effecting a chemical change in its nature where it is not protected by the grease or ink of the drawing. The carbon is freed and a nitrate deposited in the form of a full-grained pellicle, the pores of which re tain the gummed water, thus creating a sur face impermeable to grease. Furthermore the drawn parts are rendered insoluble in water by decomposing the alkali contained in the crayon or ink. The object of this etching is not to elevate the drawing so much as to make the impression cleaner and sharper.