The Invention of Lithography Part 27

But it requires great skill, lacking which one may destroy his plates utterly.

EXAMPLE IV

_To change an intaglio design into relief for easier printing_

Many kinds of scripts and designs are easier to engrave with a needle than to do in relief with a pen; or one may have workmen who can use the engraving tool better than the pen, as the use of the latter requires more industry and skill than the use of the etching- or engraving-needle.

If one wishes to transform such a design into one in relief, because then it can be printed more quickly and easily and also will give more impressions, the following method will prove useful:--

Ink the stone with good acid-proof ink, and after a few hours etch it like a pen design till it is apparent that the design is showing up. Let it rest again a few hours after etching and become quite dry. Then coat with gum. Otherwise treat it for printing like an ordinary pen design.

Now I believe that I have described faithfully and as clearly as I can all the lithographic methods to which unceasing research and endless experimentation have led me. In the following Appendix I merely make a few useful remarks, which do not pertain exclusively to lithography, yet are intimately connected with it and surely will not be unwelcome to art lovers.

[Ill.u.s.tration]

APPENDIX

I

PRINTING WITH WATER AND OIL COLORS SIMULTANEOUSLY

When a plate, whether intaglio or relief, has been inked-in with oil color, it may be coated with one water color, or it may be illuminated with several, and then printed-off in one impression. Two parts of gum and one part of sugar are used for this. They can be dissolved with any water color. Care need be taken merely that the colors are well dried before the impression is made.

If, however, it is desired that the colors have shades so that the impressions may resemble English or French colored copper-plate prints, the process is as follows:--

Etch all shades of the color pretty deeply in any of the stippled or aquatint styles. After this, coat the stone with gum solution, that it shall take no color in these depressions. Clean off the chemical ink or the ground with oil of turpentine, and prepare the whole plate if it has not been prepared already on its surface. Then coat it with red gum surface, and into this inscribe all those lines that are to remain black. Then the color is rubbed-in and the stone cleansed so that it will be white everywhere except in the engraved parts. When it is inked-in now, it can take color there only, and the other depressions (namely the various shades of the color) will remain white because they have been prepared. Now it is necessary only to coat each part with the desired water color and it will be denser, and therefore darker, wherever there are more and greater depressions.

II

SIMULTANEOUS CHEMICAL AND MECHANICAL PRINTING

When a pen drawing is so const.i.tuted that the various lines are close together and there is no white s.p.a.ce on it that is greater than at most one half inch in diameter, it will permit printing in a purely mechanical way without being prepared. It need merely be etched into all the relief possible without under-eating the lines. All that is needed then is a color-board or a so-called dauber, made as follows:--

A thin board of soft wood, about eight inches long and six inches wide, is planed down till it is not more than one line in thickness. Glue on it a piece of fine cloth or felt almost as large as it. Over this glue another board, of the same area as the first, but one quarter inch thick. It must be very well-dried wood, and must be made very true with the plane, or better still, by rubbing on a perfectly level stone with sand. This latter board is provided with a handle; and when all is dry this dauber is ground off true again with fine sand and oil on a stone.

Lay the printing-color on this utensil very gently and uniformly with a leather ball. Tap and pat the stone, which has first been cleaned with oil of turpentine over its whole surface, very carefully with the appliance, holding it as horizontal as possible and taking great pains to distribute the color evenly.

As compared with chemical printing, this process in itself has no advantages, but can be united with it and thus used to print three colors from one plate. This is shown by the following

EXAMPLE

Suppose that a design shall be colored black, blue, and red, and that all these colors shall be put simultaneously on one plate. Take a stone made ready for pen work, and prepare it first of all with phosphoric acid, nutgall, and gum, then wash it with water, and let it dry. Now draw-in all that is to be red with chemical ink, that must, however, contain only just enough soap to permit its solution. When this drawing is dry, etch it into pretty high relief, the higher the better. After this prepare the stone with gum, wash it, and let it dry again. Then coat it with etching-ground that has been dissolved in oil of turpentine, and draw-in all that is to be black, between and over the high etched parts. Then etch this design pretty powerfully into intaglio, after which wash with water, rinse with alum solution, and dry. When the plate is thoroughly dry, rub-in printing-color, and clean with a woolen rag dipped into gum solution and oil of turpentine. Then it will become white everywhere except in the deep lines where it will have taken color. After cleansing again with water and drying, draw-in all parts that are to be blue, using a chemical ink that contains a great deal of soap. Let this dry well, and cleanse the plate with gum and oil of turpentine again. Then it is ready for inking-in.

To lay on the color, proceed as follows:--

First the black is rubbed-in, as prescribed in the article on the intaglio style. In the very deep parts the stone will get very black. In the parts last drawn, that are level with the surface, it will be only gray, if the color permits ready wiping, which can be facilitated by the use of gum and a woolen rag. Then the tone remaining on the level parts drawn with the chemical ink will be so pale that it will not affect the blue color. Now wipe a rag dipped in blue color gently to and fro till everything that is to be blue has taken the color well. Then take the dauber which has been filled with red color, and pat the stone, which should be dry by that time. Then the parts of the design in high relief will take the red color, and thus an impression can be made with the three colors at once. Each inking-in must be done the same way.

III

USE OF THE STONE FOR COTTON-PRINTING THROUGH WIPING. A UNIQUE PRINTING PROCESS

Etched copper plates have been used for some considerable time for cotton-printing, and as the ordinary oil colors were not suitable for this, while the suitable colors were too fluid, so that they were always wiped out of the engravings, another method was devised. The plate was covered with color and then a kind of straight edge was sc.r.a.ped across it, which removed all color from the surface, leaving it only in the depressions.

This same sort of wiping is applicable to stone, and it is necessary merely to see that the stone is very even and highly polished. The color must be one that permits itself to be wiped off clean, and the wiper must be very uniform and sharp.

Starch-paste or gum with some caustic material is easily sc.r.a.ped off.

IV

COLOR PRINT WITH WIPING

This process is also useful for printing papers such as cotton papers, tapestry, etc. Almost all intaglio designs permit good printing in this way, if a handsome color is used.

Fresh cheese, or drops of congealed milk, mixed with soap, potash, linseed oil varnish, and the desired tint, make an excellent composition, with which all intaglio designs, even aquatints, can be printed handsomely if the plate is very smooth.

If the design is made well, the various colors can be laid on quite roughly, care being taken merely that each color shall be laid only where it is desired. Then the stone should be permitted to dry, after which all the surplus colors can be sc.r.a.ped away with one manipulation, without danger that one will mix with the other in the design.

V

OIL-PAINTING PRINT THROUGH TRANSFER

Colored impressions resembling oil paintings can be made by printing with colors and several plates on paper grounded with oil color. But perfect oil paintings are produced only as follows:--

Make a considerable quant.i.ty of special paper by coating unsized paper thinly with starch-paste or glue. On this make the separate impressions from each color plate. If the painting itself is to be produced from these separate parts, take a canvas that has been prepared for oil painting and lay on it a wetted impression of one of the colors, let us say, red. Print this off under light tension of the press, and when the paper is pulled away, it will be seen that the color has been transferred to the canvas. Then a wet impression of another color is laid carefully in place so that it will register exactly, and the process is repeated, till all the colors have been transferred to the canvas.

The transferring can be done with the hand or with any other method, as no great power is needed, since the color transfers itself readily.

VI

STONE-PAPER

This is the name already generally adopted for a subst.i.tute invented by me for the Solenhofen stones.

I had been trying for a long time to invent some stone-like mixture that would be equally suitable for printing. The ordinary parchment of the writing-tablets would do if its surface were not soluble in water. I made considerable progress with a composition of lime and freshly congealed milk after the mixture had aged enough so that the lime could sate itself with oxygen. Then I made a composition of chalk, gypsum, and glue, which I dipped into a solution of nutgall and alum, and I was able to use this for coa.r.s.er work, at least, if not too many impressions were required.

I did not get a wholly satisfactory idea, however, until I observed that fat spots that were caused on a stone by oil, and also designs that had been transferred to the stone with mere oil color, refused to take color after a few weeks if they were prepared in only the slightest degree.

I reasoned from this that oil suffered a change from exposure to air, and by combining itself presumably with oxygen acquired a more earthy character. This deduction may be correct or not; but it led me to experiment with oil as a binder for various earthy substances, because I reasoned that such a composition would be insoluble in water. The only question, then, would be if despite the intermixed oil it would permit itself to be prepared, that is, if it could be made resistant to other fats.