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The stone used in lithography is a limestone (carbonate 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 corrode its surface, and dispose it to imbibe moisture, with 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 wood-cuts, 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 and by engineers, 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 instrument, and is 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 lithographer. It is applicable to engravings on either stone or metal, and it is done from copper-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 it was for some years regarded as one of the most valuable secrets of the lithographic art. Engravings 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 engravings, printing 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 well-prepared transfers can scarcely be distinguished from those printed from copper or steel-plates.
Take the outline of the original design upon transparent paper, by tracing all the lines of the original with a dry point; the outline is then glued by its edges on a board, and there is spread over it, with a piece of fine linen, a tolerably hard paste, formed of lithographic ink, dissolved in essence of turpentine. The outline is then rubbed hard with a piece of clean linen, until the linen ceases to have a black tint. The outline is then transferred to the stone by means of the press, placing in a vertical paper press the stone and the outline in contact, laying upon the latter 25 sheets of paper, wetted in water with some solutions of calcined muriate of lime. Upon these last sheets are placed large plates of paper, about 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 paper is to be removed by hot water and the design will be left on the stone, which is now washed with cold water till no trace of the paper remains.
Soap, 1/4; mutton-suet, 1/2; yellow wax, 1 part; mastic in tears, 1/2; and as much lampblack as necessary.
In the chemical printing office at Vienna, 3 different methods are employed, but that termed in relief, is most frequently used. This is the general mode of printing music.
The 2nd method is the sunk, which is preferred for prints.
The 3rd method is the flat; that is, neither raised nor sunk. This is useful for imitating drawings, particularly where the impression is intended to resemble crayons. For printing and engraving in this method, a block of marble is employed, or any other calcareous stone that is easily corroded, and will take a good polish. It should be 2 1/2 inches thick, and of a size proportioned to the purpose for which it is intended. A close texture is considered as advantageous. When the stone is well polished and dry, the first step is to trace the drawing, notes, or letters to be printed with a pencil; the design is not very conspicuous, but it is rendered so by passing over the strokes of the pencil a particular ink, of which a great secret is made. This ink is made of a solution of lac in potash, colored with the soot from burning wax, and appears to be the most suitable black for the purpose. When the design has been gone over with this ink, it is left to dry about 2 hours. After it is dry, nitric acid, more or less diluted, according to the degree of relief desired, is poured on the stone, which corrodes every part of it, except when defended by the resinous ink. The block being washed with water, ink, similar to that commonly used for printing, is distributed over it by printer's balls; a sheet of paper disposed on a frame is laid on it, and this is pressed down by means of a copper roller or copper press.
The sunk or chalk method differs from that termed relief, only in having stone much more corroded by the nitric acid. In the flat method less nitric acid is used. It is not to be supposed that the surface is quite plain in this way, but the lines are very little raised so that they can scarcely be perceived to stand above the ground, but by the finger.
Mix the following ingredients: Soap, 3 oz.; tallow, 2 oz.; wax, 1 oz.
When melted smooth, add a sufficient quantity of lampblack, and pour it into moulds.
The stone should be close grained, and the drawing or writing should be made with a pen dipped in ink, formed of a solution of lac, in lyes of pure soda, to which some soap and lampblack should be added, for coloring. Leave it to harden for a few days; then take impressions in the following manner: Dip the surface in water, then dab it with printer's ink and printer's balls. The ink will stick to the design and not to the stone, and the impressions may be taken with wet paper by a rolling or screw press, in the ordinary way. Several hundred copies may be taken from the same design, in this simple manner.
Paste-board, or card-paper, covered with an argillocalcareous mixture, has been employed with complete success, and effects a great saving. The material is to be reduced to a powder, and laid on wet; it sets, of course, immediately, and may be applied to a more substantial article than paper, and upon a more extensive scale than the inventor has yet carried it on. This coating receives the ink or crayon in the same way that the stone does, and furnishes impressions precisely in the lame manner.
Another substitute for lithographic stone is zinc, which has been used to some extent lately for transferprinting. The transfer is made on the surface from an engraving on metal or stone, and the method is nearly the same as that alluded to above.
Printing in colors is now much practiced in lithography, and quite attractive show-cards, lamp-shades, etc., are produced. Every color requires a separate design or drawing, and one color only is printed at a time. Skill and care is required in registering, as it is called, or in making the colors properly join together in the picture, and also in preparing the colors. Parts of pictures intended to be colored by hand in the usual manner, can frequently be printed more cheaply.
Photographing on stone is perhaps at present the most interesting of newly discovered processes in lithography. It is very useful in making either reductions or enlargements of drawings or engravings intended to be printed from stone, and is also applicable to obtaining and fixing figures of minute objects obtained by means of the microscope. The surface of the stone is prepared in a suitable manner, and the photograph made upon it, after which it is treated and printed as in other processes of this art. This method has at present the appearance of becoming very important and useful in lithography.
A process of veneering by transfer is mentioned with approval in the French journals. The sheet of veneer or inlaying to be copied, is to be exposed for a few minutes to the vapor of hydrochloric acid. This novel plate is then laid upon calico or paper, and impressions struck off with a printing-press. Heat is to be applied immediately after the sheet is printed, when a perfect impression of all the marks, figures, and convoluted lines of the veneer is said to be instantaneously produced. The process, it is affirmed, may be repeated for an almost indefinite number of times. The designs thus produced are said all to exhibit a general woodlike tint, most natural when oak, walnut, maple, and the light-colored woods have been employed.
Moisten a sheet of paper with benzine, by means of a sponge. The paper becomes temporarily transparent, and lines may be traced through it. In a few hours the benzine evaporates, and the paper becomes opaque as before.
The process now adopted by many newspapers is to take a cast of the form in a composition of strong glue, with alum and plaster of Paris. Into this the metal is poured. It requires only sixteen minutes to mould, cast, and finish the stereotype plate.
On a plate of chalk or plaster, the artist sketches the design with a gummy ink (at present a secret). By means of a silk rag, the portions of the plate not protected by the ink are rubbed away. A copy is then obtained in fusible metal or by the electrotype.
If the original be a plant, a flower, or an insect, a texture, or in short, any lifeless object whatever, it is passed between a copper plate and a lead plate, through two rollers that are closely screwed together. The original, by means of the pressure, leaves its image impressed with all its peculiar delicacies -- with its whole surface, as it were -- on the lead plate. If the colors are applied to this stamped lead plate, as in printing a copper plate, a copy in the most varying colors, bearing a striking resemblance to the original, is obtained by means of one single impression of each plate. If a great number of copies are required -- which the lead form, on account of its softness, is not capable of furnishing -- it is stereotyped, in case of being printed at a typographical press; or galvanized, in case of being worked at a copper-plate press, as many times as necessary; and the impressions are taken from the stereotyped or galvanised plate instead of from the lead plate. When a copy of a unique object, which cannot be subjected to pressure, is to be made, the original must be covered with dissolved gutta percha; which form of gutta percha, when removed from the original, is covered with a solution of silver, to render it available for a matrix for galvanic multiplication.
This process is also applicable to the purpose of obtaining impressions of fossils, or of the structure of an agate or other stone. In all the varieties of agate, the various layers have different degrees of hardness. Therefore, if we take a section of an agate and expose it to the action of hydro-fluoric acid, some parts are corroded and others not. If ink is at once applied, very beautiful impressions can be at once obtained; but for printing any number, electrotype copies are obtained. These will have exactly the character of an etched plate and are printed from in the ordinary manner. The silicious portions of fossil, and the stone in which they are imbedded, may in like manner be acted upon by acid, and from these, either stereotyped or electrotyped copies are obtained for printing from.
The process is one by which images of foliage may be taken by any who have leisure and choose to devote an hour or two to the registration of the beautiful forms of our leaves. The process, by its simplicity, commends itself; and the results gained are of the most charming character. The Vienna process of nature printing has achieved much, and produced results of the most admirable character, but the process necessitates the use of dried vegetable specimens, in order to the production of the image. While this is at least no drawback in the case of ferns, and is perhaps even an advantage, yet it strongly militates against the process in the case of many other plants. In order to meet this difficulty, Dr. Dresser suggested an "Improved Nature Printing" process which he patented, in conjunction with Dr. Lyon Playfair, in which impressions are taken from the living plant, and which may be substantially described as follows: A sheet of foolscap writing-paper should be provided, a handful of fine cotton-wool, a piece of muslin, one or more tubs of common oil-paint (according to the color required), a little sweet-oil, and a quantity of smooth, soft, cartridge-paper, or better, plate-paper. Having placed the sheet of foolscap paper while doubled (the two thicknesses making it a little softer), on a smooth table, squeeze from the tube about as much oil-color as would cover a shilling, and place this on one corner of the sheet of foolscap; now form a "dabber" by enclosing a quantity of the cotton-wool in two thicknesses of muslin, and tying it up so as to give it roundness of form. Take up a portion of the oil-paint from the corner of the paper, with the dabber, and by dabbing give the central portion of the sheet of foolscap a coat of color. This dabbing may be continued for half an hour or more with advantage, taking a small quantity more color when the paper becomes dry; two or three drops of sweet oil may now be added to the paper and distributed by the aid of the dabber, if the color is thick, when the paper will be fully prepared for use.
The paper may be left for an hour or two after being first coated with color without injury, and, indeed, this delay is favorable, for until the paper becomes impregnated with oil, the results desired are not so favorable as they become after the paper is more fully enriched with this material. While the color is soaking into the paper, a number of leaves should he gathered which are perfect in form and free from dust, and these can be kept fresh by placing them in an earthenware pan, the bottom of which is covered with a damp cloth, but it will be well to place a damp cloth over the orifice of the pan also. Selecting a woolly, hairy leaf, place it on the painted portion of the sheet of foolscap, and dab it with the drabber till it acquires the color of the paint used; this being done turn the leaf over and dab the other side; now lift it from the paint paper by the stalk, and place it with care between a folded portion of the "plate" or "cartridge" paper, and if the stalk of the leaf appears to be in the way, cut it off with a pair of scissors; now bring down the upper portion of the folded piece of paper upon the leaf, and rub the paper externally with the finger, or a soft rag, bringing the paper thus in contact with every portion of the leaf. If the paper is now opened, and the leaf removed, a beautiful impression of both sides of the leaf will be found remaining. In like manner, impressions of any tolerably flat leaves can be taken; but harsh leaves will be found most difficult, and should hence be avoided by the beginner. While the paper is yet rich in color, downy leaves should be chosen; but color may at any moment be added, care being always taken to distribute the paint evenly over the paper with the dabber before the latter is applied to the leaf, and the dabber is always removed from the painted paper till the color is exhausted, when the paper is again replenished from the reserve in the corner.
As the color on the paper becomes less and less in quantity, smoother leaves may be employed; and when the paper seems to be almost wholly without paint, the smoothest leaves will prove successful, for these require extremely little color. Should the natural color of the leaf be desired, it can be got by using paint of the color required; but, in many cases, purely artificial tints produce the most pleasing and artistic results; thus, burnt sienna gives a very pleasing red tint, and of all colors this will be found to work with the greatest ease.
By the process now described, the most beautiful results can be gained, but the effect will be better, if, when the impression is being rubbed off, the leaf, together with the paper in which it is enclosed, is placed on something soft, as half a quire of blotting paper. Should the first attempt not prove very satisfactory, a little experience will be found to be all that is required, and now the most common leaf will be seen to have a form of the most lovely character.
Collections of leaves of forest-trees will prove of the deepest interest, or of all the species which we have of any kind of plant; thus, if the leaves of the black, red, American, and golden currant be printed together with that of the gooseberry, all of which belong to one botanical genus or group, the variation or modification of the form will be seen to be of the deepest interest.
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