The Invention of Lithography Part 23

When the design is finished and very well dried, the entire surface of the stone is rubbed gently with a fine cloth, in order to perforate the color with tiny holes everywhere. As it will perforate more readily in the parts where the ink has been laid on thinly, the succeeding aquafortis will eat through there more easily, and thus the etching will correspond nicely with the tones of the design. It is necessary, however, to know the strength of the acid and the resisting power of the ink very accurately. It is well to experiment and write down the best proportions. In any case, the etching fluid must not be too strong and the etching must not be done by pouring or brus.h.i.+ng, but in the copper etcher's manner, by framing the stone with wax so that the fluid will lie on the stone. As soon as the resulting bubbles reach the magnitude of a pin's head, the fluid is poured off instantly and then poured on again till the bubbles reappear. How long this must be continued depends on the strength of the ink.

It is understood, of course, that the etched stone must then be coated with gum.

VI

THE SPATTER METHOD

This speedy and easily executed style surely will come into wide use soon. It is done as follows:--

The outlines of a design are laid on a stone prepared for pen work, by tracing. Then they are traced again, say four times, on sheets of paper.

On each sheet everything that falls into the category of one of the four chief tones is cut out with a sharp penknife so that the four sheets are like the stencils of card painters. Now the chief lines of the design are made on the stone with chemical ink, using either brush or pen. Lay one of the stencils on it exactly, weight it that it may not move, and perform the operation of spattering.

This is done by dipping a small brush, such as a clean toothbrush, into chemical ink and sc.r.a.ping it with a knife so that the ink is spattered over the stone. Care must be exercised not to have too much ink in the brush, for fear of blots or over-large spattering. After practice it will be possible to produce such fine and uniform dots as cannot possibly be produced by the pen. After the desired grade of shading has been achieved, the stone is permitted to dry. Then the second stencil is laid on and the operation repeated till all have been used. If enough stencils are made, the whole design can be made by spattering. It is not necessary, however, to make many, as the design has to be finished up by hand afterward anyway.

This finis.h.i.+ng-up is done first with the engraving-needle, which opens and decreases all dots that are too large, and then with the pen, which brings out the true proportions of the various tones.

VII

TOUCHE WITH SEVERAL PLATES

This really is only a process of using many tint plates. It makes splendid effects possible, equal to any produced by an artist with Chinese ink, and deserves the attention of all artists, especially as it is the easiest and quickest of all methods, even though it is a little circ.u.mstantial in the printing.

Draw the outlines of a design on the stone in chemical ink with pen or brush, and then make four, five, or six transfers on stone plates prepared for pen work. Register marks must be on the design. Now draw-in the darkest parts on the first plate, the less dark ones on the second, the lighter ones on the third, and so on till the whole design is finished. The work is best done with a brush. One or more of the stones may be designed with crayon; but the number of stones designed with ink must be greater, in order to make the grain of the crayon designs unnoticeable.

The etching is done as in pen work. For each stone the printing-color is chosen according to the tone of its design. Of course particular accuracy is vital; but the artist should not permit the apparent difficulties to frighten him, as he will see very soon after trial that no other method produces such beautiful results.

VIII

COLOR-PRINTING WITH MANY PLATES

This method, in which the various colors are drawn on several stones, either with pen or crayon, resembles the one just described.

According to treatment the impressions will resemble a painting, a copper-plate engraving in color, or an illuminated copper-plate engraving, if the color stones are used merely to lay colors over a design already printed in its entirety in black.

The whole process is so like the preceding one that I need merely recount the colors that I have found serviceable for the purpose.

RED. Vermilion, red lake of cochineal, fine madder lake, and finally carmine if it is mixed first with Venetian turpentine before being combined with varnish, as otherwise it inclines to separate from the varnish and unite with water, staining the whole printing-paper red.

BLUE. Berlin blue and mineral blue. Use only a small amount, sufficient for a few hours. These colors dry quickly, and, besides, make the varnish too tough, so that they must be thinned down from time to time with a little linseed oil. Fine indigo is very good, also a blue lake that is made of logwood and verdigris. This latter is not durable in sunlight.

I have had no success as yet with green or yellow.

Verdigris is difficult to manipulate because it s.m.u.ts the stone easily and does not tolerate many mixtures. Schweinfurther green, one of the new colors, is much better in all respects, but not dark enough.

Mixtures of yellow lake with indigo or mineral blue are not very durable. Golden yellow ochre with mineral blue or indigo does not produce a pretty green, and King's yellow mixed with blue is handsome but not durable. Neapolitan yellow and the newer chrome yellow with blue produce a green that is not dark enough.

I have obtained the handsomest and darkest green by printing the design blue first and then printing over it a yellow plate, so that the yellow lay over the blue. By using Berlin blue and fine ochre a fairly handsome color is produced. On account of its loss of color in water, ochre cannot be used unless Venetian turpentine is first mixed with the varnish.

A handsome and at the same time dark yellow is equally hard to obtain.

Till a good color is invented, we must content ourselves with ochre, Terra de Sienna, Neapolitan yellow, mineral yellow or chrome.

This printing with various colors is a process for which the stone is superior; and it is susceptible of such perfection that in future true paintings will be produced by its means. My experience convinces me of this.

IX

GOLD AND SILVER PRINTING

This process is useful for decoration.

Those parts of the design that are to appear in gold or silver are drawn with chemical ink on a stone prepared for pen work. After the drawing is dry, it is etched and prepared in the usual way. The printing is done with a silver gray color of firm varnish, fine crayon and a very little lampblack. The paper must be entirely dry and very smooth. Soon after the impression has been made, the printed parts are covered with silver or gold leaf such as is used by gilders. It is pressed on slightly with cotton, that it may adhere, and then a sheet of paper is laid over it.

Then the second impression is made, treated the same way, and so on.

No more impressions must be made than one can cover with silver or gold in two hours. If the ink is on the paper too long, it will draw in and not take the metal well. After gilding or silvering, the sheets must lie for some hours or till the next day, that the ink may take perfect hold of the paper, so that, in the succeeding pressing, it will not penetrate the metal and make it look sooty. The pressing is done by laying six or eight impressions on a clean stone under the press and pa.s.sing them through as for printing, with the proper tension. This tension must be adjusted according to the firmness of the printing-color; therefore it is best to make test with one sheet. Then, if the metal does not adhere sufficiently, the pressure can be increased.

In the end all surplus gold or silver is removed by gentle wiping with clean cotton. This is easy, as it will have fastened itself only to the printed parts. If the impressions can be set aside for some days without being wiped, it is better, and there is not so much danger of injuring the brilliancy of the metal.

If gold and silver are to be printed on designs where there is other color also, or where there is black, the print on which the metal is to be applied must always be made first. Only when the sheets have been gilded or silvered, pressed, wiped, and cleaned, is the black design to be printed on from the next plate. That all this must be done with the register marks previously described is, of course, self-evident.

So I close my description of the Relief method; and I hope that I have made it all so clear that good results will come to all who follow my directions.

CHAPTER II

INTAGLIO METHOD

This differs from the other in that the fat, which is to attract the printing-color, is under the surface of the stone, the design having been either engraved-in or etched, and then filled with fat.

Like the preceding method, it has several branches. The best are these:--

I

THE LINE ENGRAVED STYLE

This is one of the most useful branches of lithography, and if the artist has attained enough skill and the printer knows his trade, it approaches very near to the handsomest copper plates, and at the same time is about three times easier and quicker than work on copper. It is splendidly adapted for writings and charts.

Choose a hard, uniform stone of the best kind. Grind it as finely as possible. Etch with aquafortis and prepare with gum. This, at least, was my early method, and it has remained in use in all printeries. Later, however, I discovered that it is almost better to coat the stone with gum without previous etching, because it can be more easily worked then.

Only in that case it must be perfectly clean and contain no concealed fattiness. Immediately after the stone has been coated with gum (not some hours later, as many do) the gum must be removed with water, that it may not penetrate too deeply and thus cause a condition which will prevent the finest lines from taking on color subsequently.

Then coat the plate with a tint made of gum solution and lampblack or red chalk. Use a soft brush to make the coating very thin and uniform.

It has the double purpose, first, of giving the stone a color so that the engraver can see his work, and of covering the prepared surface of the stone with a protective coat that later will admit the fatty printing-color only where it has been pierced by the engraving-tool. It is evident that this latter property is increased according to the amount of gum in it, yet only little gum must be used in it, the permissible amount being only just enough to insure that the coating shall not be easily wiped away during the work of engraving.