The Invention of Lithography Part 22

To achieve this, the practice used to be to draw two register marks on the stone holding the original design, which were transferred to the tint plate with the rest of the design. When the first impression was made, the printed paper was cut away exactly at the marked points, and laid accurately, on the tone plate, being guided by the two marks there.

This was effective, but it had the fault that the paper had to be trimmed off carefully for each impression and that the slightest inaccuracy spoiled the register. However, it is very useful for printing proofs.

It is far better to have a printing-frame that is so fixed that it will never shift its position in the slightest degree. To this is fastened a little movable frame that has two steel needles whose position is adjustable at will. Lubricate the leather inside with wax and lay a sheet of white paper on it. See that the tint plate is so fastened in the press that it cannot stir out of place. Make an impression and take care especially that the two register marks print off well. Now set the needles in the little frame so that they will be exactly over these two marks. If, then, an impression of the design is laid on so that the two guiding-marks on it come exactly under the two needles, it will, of course, register perfectly. Of course the little frame must be so adjusted that it can be folded back out of the way before each impression, and the printing-frame must hold the sheets of paper so that they cannot move.

To color the tint plate, use a firm varnish tinted with umber, or any other color that will give the desired effect. New rollers are best, insuring a fine, even, unspotted tone.

(3) In rough-grinding the stones, it is difficult to prevent scratches and furrows caused by the coa.r.s.e sand. No design of value should be made on such a stone, but if one is used, the defects should be touched up with chemical ink and a fine brush, as crayon will hardly do it.

(4) As the delicate places in crayon work are not durable, etching having the property of reducing the light portions and darkening the darker ones, I tried the method of drawing the lighter portions on a separate stone in rather stronger manner and printing from it with paler ink. The success was so great that I hope in time to produce true masterpieces with the aid of skilled artists, and here call attention to it in advance.

(5) After learning how to make a second impression over a first one, it is not difficult to pa.s.s on to printing with several stones and from that going on to color-printing. In the early days of my invention I tried color-printing with a crayon plate and had the best success by using stencils such as are used by the painters of cards. On oiled stiff paper I made as many impressions of a design as there were to be colors.

Then all that was to be red was cut out from one stencil, green from another, and so forth. Then the stone was wetted, the stencil laid on it and the uncovered parts of the stones inked-in with the right color.

After all the colors had been applied, I made the impression, which generally looked neat enough, but still resembled a sketchy drawing rather than a painting, because no color except black, zinc red, and dark blue permitted itself to be printed strongly enough. But by using several stones, each of which can be designed and treated according to the necessities of color, impressions can be made that resemble the English colored copper prints very closely, especially if the crayon and pen or brush methods are united.

(6) A stone plate may be etched so that it will have the roughness needed for crayon work. Grind it as clean and smooth as possible with pumice, pour aquafortis over it and coat with gum. Wash it well in water and dry with a clean cloth. Coat it very thinly but uniformly with tallow into which is mixed a little lampblack, so that one can see if the coating is perfectly even. With a small ball or roller covered with fine cloth, roll or pat the stone till it has a very uniform tone. Now pour a little diluted aquafortis on one end as a test to see if it penetrates uniformly through the fatty coating. Practice is needed to hit just the right thickness that the tallow coating must be. It must be thin, and yet sufficiently thick to resist the aquafortis somewhat, so that it yields only at those places where the roughness of the cloth on the roller has removed it more or less.

If the test is satisfactory, make a raised border of wax around the stone and pour the aquafortis solution on it. A solution of forty parts of water to one part of aquafortis is better than a stronger one because the stones are more equally attacked. As soon as the resulting bubbles are as large as the head of a small pin, the etching fluid is poured away quickly and replaced with pure water to get rid of the bubbles.

Pour away the water and apply etching fluid again. Repeat this four or five times, according to the grain desired, and in the end wash the stone well with oil of turpentine to remove all fattiness. Then it must be washed with weak but very pure aquafortis, followed by a great deal of very pure water. After cleaning and drying very carefully with a clean rag, it is ready for use; and if the work has been well done, a grain will have been produced that is prettier and much more even than can be produced by rubbing with sand.

(7) The instructions given here teach how to draw on a stone that has been prepared beforehand with aquafortis and gum. This is not in the least inimical to the durability of the design if only the union of the gum with the stone has been destroyed again by washing afterward with diluted but pure aquafortis and every trace of this acid again has been removed by copious washing with pure water. If there is a considerable amount of the soap in the crayon, the good result will be greater than with an entirely clean stone, because, since it has already been etched twice, the etching after the design may be very limited, so that it is not harmful to even the most delicate shadings in the design.

(8) Some attempts made by me to etch crayon designs more powerfully than usual proved that the more delicate places would suffer, but if I rubbed them up with a flat knife as described before, they appeared again and I had the advantage that the whole plate was much better prepared than it is with weak etching.

(9) If a crayon plate is spoiled in printing through carelessness or lack of skill, the rules for remedying the trouble are the same as those named for pen work, and the judgment of the worker must decide which method is the most applicable. In general, it may be a.s.sumed that the best remedy for blurred spots is to draw them over again with crayon; and for s.m.u.tted parts the best is to apply firmer printing-color, or to cleanse with oil of turpentine and gum and afterward ink-in with acid-proof ink, and then use light etching with weak aquafortis followed always by coating with gum and water.

III

TRANSFER AND TRACING

In the pen and crayon method all the lines that are to take printing-color are drawn directly on the stone with a fatty preparation.

But lithography has a unique way of transferring to the stone a drawing or inscription that is first put on paper with the fatty substance. This is possible only for lithography, and I incline to the belief that it is the most important of all my inventions. It makes it unnecessary to learn reverse writing. Everybody who can write on paper with ordinary ink can do so with the chemical transfer ink, and this writing can then be transferred to the stone and manifolded indefinitely. In Munich and Petersburg this method has been introduced for government work. The measures adopted in council are written during the session by the secretary, with chemical ink on paper, and sent to the printery. Within an hour impressions are ready to distribute among the members. I am convinced that within ten years every European Government will have a lithographic establishment.

In war the method would have a great value. It would replace the field printery, and it permits greater speed and secrecy. The commander need merely write his orders himself and have them printed in his presence by a man who cannot read, to be sure that his plans will not be betrayed.

The engineer officers can draw plans and have them circulated among the officers who need them.

Authors and scientists will find the method to be the means of circulating their works in ma.n.u.script very cheaply.

Even artists will respect the method when its gradual perfection enables them to draw their pictures on paper with ink or crayon and reproduce them.

Not from boastfulness, but from conviction of the importance of the method, have I thus recounted its advantages. I could fill a whole book with detailed explanations. I wish to gain friends for the method, that it may be improved to its ultimate degree by skilled artists.

The chemical ink used for the paper may be soft or firm. The paper may be specially prepared or not. The stone may be warm or cold. The design leaves the paper entirely and clings to the stone, or does so only partly. To describe all this would take too much s.p.a.ce. I will describe only the method that I consider best, namely, a method under which the work is done with a soft ink, and transferred to an unwarmed stone. This is the quickest and surest, and has the advantage of not spoiling the original.

In a clean coffee cup rub down a piece, as large as a hazel nut, of the chemical ink described under the heading "Transfer Ink" in an earlier part of this work. Dissolve with rain water or soft river water. The amount of water is determined according to the need for fine or coa.r.s.e work. In the latter case, the ink should be thinner, that there may not be too much ink in the design after it dries.

While the writing or design is drying, select a stone that either has not been used before or at least has been thoroughly ground off, and grind it down once more with pure and dry pumice stone without water, until it is certain that all parts of the surface have been rubbed down so thoroughly that the stone may properly be considered a new one. Clean away the dust with clean paper, fasten the stone in the press, examine the sc.r.a.per to make sure that it is even, adjust the press for the proper pressure; in a word, do all that is necessary for good impressions. From this time on the greatest care must be taken not to touch the polished stone with as much as a finger, not to mention keeping grease and dirt away from it.

As soon as every point in the design on the paper is perfectly dry, wet it on the reverse side with a sponge dipped into weak but pure aquafortis until the paper is quite soft. Lay it between waste paper sheets for a time, to prevent it from pulling out of shape and to remove the excess moisture. It must be soft, but not wet, when the impression is made.

Lay the paper face down on the stone. On it lay two sheets of dry waste paper, then an equally large piece of taffeta, another sheet of waste paper and make the transfer print with a moderately swift motion of the press, which must have more tension than is used for ordinary impressions. The power of a lever press is insufficient for larger stones, and a cylinder press is required.

After a few minutes the stone is withdrawn from the press, the paper is lifted off and the stone permitted to dry for a minute. It is better if one can wait longer. Then put it into the etching-trough, and pour over it, quickly and only once, a clean but weak solution of one hundred parts of water to one part of aquafortis. It is necessary to be skillful enough to cover the whole surface with one application. Then the stone is washed by pouring pure water over it, and, if time permits, set aside to dry. If time is limited, the gum solution to prepare the stone can be put on at once. Now the transfer is on the stone, properly etched and prepared. To make clean impressions, however, the printing-color must first be rubbed on, then the stone must be inked-in with acid-proof color and after that undergo another etching, a trifle stronger.

To rub on the printing-color, rub a little acid-proof color into a piece of clean linen or cotton, so that it is well permeated but not thickly covered. Rub this rag gently to and fro over the transfer while the gum is still on it, till every part of the design is nicely inked. This rubbing-in of color is an important part of many of the processes that will be described later.

Now clean the stone well with water, ink-in with acid-proof ink, and etch it again as has been described several times. Then it is ready for printing. The last etching is not necessary if only a few impressions are desired.

Transfer is applicable not only for pen designs but also for crayon. The crayon used for the purpose should be softened a little with tallow, or, if the harder crayon is used, the stone should be warmed when making the transfer. But it must not be inked-in or have color rubbed on, until it is quite cold again. For crayon transfer the paper used generally is fine drawing-paper. It must be wetted with somewhat stronger aquafortis that it may release the crayon more readily. The rest of the process is the same.

Besides these two methods, the transfer process can be used for all products of the book-printer's art, type as well as wood-cut. A freshly printed sheet can be transferred directly to a stone, especially if the printer has used our before-mentioned acid-proof ink instead of his ordinary printer's ink. To get a perfectly clear transfer it is necessary merely to see that the printer does not use too much overlay, which would stamp the type too deeply into the paper; and that before trying to transfer the printed sheet to the stone it is subjected to gentle pressure in the press to free it from all inequalities. To do this without at the same time risking any loss of ink which might subsequently weaken the transfer, the sheet is well wetted, laid on a clean, wet stone that has been prepared so that it will not have any inclination to take color, and subjected to a very slight pressure, the press being used with almost no tension. This makes the printed sheet beautifully even. Then if it is transferred to a stone properly prepared as described before, the transfer will be perfect.

Even old book pages can be freshened up and transferred. I have spoken already of those that are on unsized paper. With prints on sized paper the method is as follows:--

Make a paint-like mixture of fine chalk and starch paste. Thin it down with water and paint the sheet. Dip a bit of linen rag into a thin color made of thin varnish and tallow tinted with vermilion. Touch-up the wet paper with the rag till every bit of type has taken red color. Pour clean water over it and touch-up the paper everywhere with a ball of fine cloth stuffed with horsehair. This will remove all surplus color.

Continue this till the type matter is only faintly red. Then the paper must be washed very thoroughly with many pourings of water and laid between waste paper sheets to remove all surplus moisture. The transfer and so on must be done then as in the other cases.

Good transfers can be made also from a copper-plate engraving if the copper-plate impression is made with our acid-proof ink. The ordinary copper-plate ink is not so good. It will be self-evident that designs on stone can be transferred and reproduced the same way.

The tracing process has the property in common with the transfer process that it transmits only a small amount of fattiness to the stone and requires subsequent rubbing-in of color to give it strength.

Coat a piece of thin and clean vellum paper with tallow and lampblack and wipe it off again as neatly as possible, so that there remains only a thin film, which will not s.m.u.t the stone when laid face down, unless pressure is exerted. Now draw on this with a clean English lead pencil that contains no sand, or with a composition of lead, zinc, and bis.m.u.th, and the pressure will force the design on the stone and transfer its fat, which then penetrates the stone and will give impressions. In preparing a stone thus made, greater care in etching is necessary than even in the transfer process. Very weak aquafortis solution must be used.

The process is something between pen and crayon work. It is quite applicable for sketches and pictures that are to be illuminated.

IV

CONCERNING THE WOOD-CUT STYLE

For this purpose, the stone is coated completely with chemical ink on the places where this style is to be used. As soon as it is dry, the lights are drawn into it with a steel engraving-needle that is ground to a sharp or broad point according to requirement. Those parts that are to be very white, with fine lines and specks, are best drawn in with the pen. Thus the wood-cut style differs from the ordinary pen design chiefly in character and in the treatment of the darker parts. Its practice is much easier on the stone than on wood, and it can be combined with crayon work. Etching, preparation, and printing are the same as with other styles.

V

TWO KINDS OF TOUCHE DRAWING

One of these resembles the wood-cut style in method but in effect approaches copper-plate work. The stone is grained as for crayon, etched, prepared with gum, cleansed with water, coated well with soap-water, wiped, dried, and finally coated with a thin, colored covering of fat, by either coating with acid-proof ink or with hard chemical ink.

This first etching and preparation are required to prevent the fat to be applied afterward from penetrating too deeply into the stone, so that it may adhere only to the surface.

Now the design is made on it with a steel sc.r.a.per. The manipulation is like that for making tint plates. It demands greater care, however, and better etching.

The completed design is etched (phosphoric acid being best) and coated with gum. A few drops of oil of turpentine are poured on and all the color is wiped away with a woolen rag, but without any rough rubbing.

Then the plate can be inked-in with fairly firm acid-proof ink.

The second method would excel crayon work if it were perfected. I have advanced pretty far with it. It is an imitation of the ordinary wash drawing which is done with a brush and dissolved Chinese ink on paper.

The stone, which must be very clean and free from all fat, is grained, coated with soap-water, cleaned with oil of turpentine, and dried. Then a hard chemical ink, which may contain a little more soap than usual, or the ink described for brush work, is dissolved in pure rain water and used on the stone with a brush just as it would be used on paper.