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Lithography (To Write and Engrave on Stone)

To Write and Engrave on Stone.

The stone used in lithography is a limestone (carbonate of limestone), of very hard and comcarbonate of limestone), of very hard and compact texture, admitting of being ground to a fine surface. There are three qualities recognized by dealers, which are called the blue, gray, and yellow stones, of which the blue is regarded as the best, and commands the highest price. The best lithographic stones are the production of a very limited district, in the kingdom of Bavaria. Several localities are known in the United States, and some years since it was reported that a quarry had been discovered in the State of Missouri, of very superior quality.

The stone must have the qualities of imbibing both water and grease or oil; the crayon used in drawing upon it being composed of grease, wax, soap, shellac, and ivory-black, which is also the composition of the ink used in printing, with little variation.

The stone must be rubbed down with fine sand, to a perfect level, after which it is ready to receive the drawing; a weak solution of nitric acid should be thrown over the stone. This operation will slightly slightly corrode its surface, and dispose it to imwith more facility. While the stone is still wet, a cylinder of about 3 inches in diameter, covered with common printer's ink, should be rolled over the whole surface of the stone.

While the wet part refuses to take the ink, the chalk, being greasy, will take a portion of it from the roller. The stone is then ready for printing.

The press consists of a box drawn by a wheel, under a wooden scraper, pressing on it with great power. After the first impression, the stone must be wetted afresh, again rolled over with the cylinder, drawn under the scraper, and so on.

The same process is employed for ink drawings, except that the solution of nitric acid must be stronger, and the printing ink stiffer.

Imitations of wood-cuts are produced by covering the stone with lithographic ink, and scraping out the intended lights. As the finer touches may be added with a hair pencil, prints far superior to wood-cuts may be obtained, but the chief advantage of woodcuts, that of printing them at the same time with the text of the book, is lost.

Within the last 20 years the art of engraving on stone has been brought to great perfection, and at this time nearly all maps used for school atlases, , surveyors, etc., and nearly all bills of exchange , checks, drafts, and other blanks used for commercial purposes are thus engraved.

The engraving is done with a pointed or sharp inis very similar to copper-plate engraving. The engraved stones are printed only when very small editions are required, transfers from these to other stones being much more easily printed.

The art of transferring and printing from transfers is now one of the most important and useful processes of lithography, and in the United States constitutes the greater part of the business of the either stone or metal, and it is done from copperlithographer. It is applicable to engravings on plates, to a considerable extent, in maps, charts, and other engravings , which consists mainly of lines and letters, without elaborate shading. This process was invented in Europe about 30 years since. An impression is taken from the engraved plate or stone with a greasy ink, and on paper having the surface prepared with a composition which is essentially albumen . This impression is carefully applied to the surface of another stone, and on removing the paper by dampening it, and with very careful manipulation, the impression in ink remains. It is then treated with diluted acid precisely as a drawing, and becomes fixed, as it is technically called, in relief on the stone, and can be printed from with entire facility. Much care is required in this process, and the method of doing valuable secrets of the lithographic art. Engravit was for some years regarded as one of the most ings of any kind can, of course, be transferred, but in finely engraved pictures, or when there is much shading, the fine lines become massed together, or blurred in transferring. In printing small maps or other suitable descriptions of enprinting from transfers has a great advantage over plate -printing, in the fact that several copies of the same engraving can be put upon the stone at once, and thus printed much more rapidly and economically. Maps printed from wellprepared transfers can scarcely be distinguished from those printed from copper or steel-plates.

Laurent's Method of Drawing in Stone.

Take the outline of the original design upon original with a dry point; the outline is then transparent paper, by tracing all the lines of the glued by its edges on a board, and there is spread paste, formed of lithographic ink, dissolved in esover it, with a piece of fine linen, a tolerably hard sence of turpentine . The outline is then rubbed hard with a piece of clean linen, until the linen transferred to the stone by means of the press, ceases to have a black tint.

The outline is then placing in a vertical paper press the stone and the sheets of paper, wetted in water with some soluoutline in contact, laying upon the latter 25 tions of calcined muriate of lime. last sheets are placed large plates of paper, about Upon these 1 inch thick, to prevent injury from a thick and straight plank, which is to be laid over them.

Pressure is now applied for 1 hour, when the outline will be found adhering to the stone. The sign will be left on the stone, which is now paper is to be removed by hot water and the dewashed with cold water till no trace of the paper remains.

Thenard and Blainville's Lithographic Ink. mastic in tears, 1; and as much lampblack as Soap, 1; mutton-suet, 1; yellow wax, 1 part; necessary.