Part 24 (1/2)
The stone must be absolutely dry before any work is done on it. Then the design is traced on it, or drafted directly on it with lead. Transfer by printing from paper is not advisable, because the resulting fattiness of the design makes the graver slip.
For the actual work of engraving there is no counsel to be given except to choose good and sharp needles of the very best steel, hard enough to cut gla.s.s; and that all lines must be graved clean. There must be no excessive pressure, and in wide strokes there must be no excessive depths. In making very fine lines the stone should merely be touched by the tool. If they appear white, and a little fine dust is observed, one may be certain that they will appear properly in the printing. Broad lines often can be made with one stroke of a flat needle, but generally they are made by continued, gradual sc.r.a.ping. If the stone is to be only lightly wiped during printing, the broad lines must not be deeper than strictly necessary to make them clear, as otherwise they will squash. In true art works, however, which are to be printed with firm color and under more powerful rubbing and wiping, the depths of all lines must be considered carefully, as they will print darker or lighter according to depth.
Of all things the worker must take heed against touching the stone with dirty or greasy hands, for a plate thus blemished is not only difficult to engrave, but the grease finally may penetrate through the slightly gummed coating and enter the stone, making much consequent trouble when the printing begins.
It is more harmful still to wet the stone in any way, because then the coating gum will dissolve, penetrate into the engraved lines and give them a preparation, so that they cannot take color afterward. Therefore, especially in winter, a very cold stone must be warmed before working on it with the design, as otherwise the moisture in the room will precipitate itself on the stone. Even the perspiration of the hands or the moisture of the breath may cause damage. Therefore a good but careful warming is very advisable.
If a plate has become moistened, as, for instance, from a breath, it must be permitted to dry before doing any further work on it, and especially it must not be wiped.
The dust resulting from the engraving is to be removed either with a soft brush or by blowing it away.
Faulty lines that are noticed during the engraving may be sc.r.a.ped flat very carefully so that no furrows are made, or they may be rubbed off with fine pumice, after which those places must be prepared again, and coated with gum applied with a small brush. Then the corrections can be made. If only tiny places are faulty, they need merely be coated with a mixture of weak phosphoric acid, gum, and lampblack or red chalk. This prepares them. Thus they will not take color during the print, and so are practically removed.
When the design is finished, the stone must be very dry that it may take color well. But it must not be warmed, as this would incline it to take s.m.u.t. A color consisting of thin varnish, a little tallow, and lampblack is now rubbed swiftly into all the depressions, and immediately wiped away again with a woolen rag wetted with gum solution. This removes the original red or black coating also.
Thus the hitherto colored stone becomes perfectly white, while the engraved design, which has appeared white, is now black. The first impression that the eye will gain will be that now the design appears much finer than it did before. That is because every white line on a dark background looks wider than a black line of the same thickness on a white background. Therefore, while engraving, the artist should aim to make his lines a trifle bigger than his eye would suggest.
In printing the stone the usual precautions required in every form of lithographic printing must be observed. Beyond that, the matter of chief importance is the proper composition of the printing-color.
Stone plates made in this way can be inked-in (1) by rubbing-in the color and light wiping, and (2) by harder wiping, and (3) by the ink-roller.
For the first method, a color can be made of thin varnish and burned lampblack, the latter being present in fairly large quant.i.ty but very finely rubbed-down. Into this color is mixed a quant.i.ty, equivalent to one half the ma.s.s, of gum solution that is almost as thick as the color itself. Everything must be mixed perfectly. If the solution is too watery, it is not easy to mix it.
Three clean rags of cotton or linen are needed for inking. The first is used to wet the stone and to clean it again in the end. The second is colored with a small quant.i.ty of printing-color and rubbed in by thorough wiping to and fro. The third rag is used to clean away any surplus that may adhere. Then the first clean rag is used to cleanse the stone thoroughly.
All three rags must be wetted with gum solution, and the first and third must be washed several times during the day.
The stone plate is harder to clean at first than after some fifty impressions have been made. Often there will remain little specks of color on the prepared places, which are easy enough to wipe away but are inclined to reappear. To remedy this it may be necessary to use more clean rags in the beginning or more gum solution. If the stone has been polished very well in grinding, this trouble will not be very noticeable if at all. Under any circ.u.mstances, it will disappear gradually during the printing, so that at last it will be possible to clean the surface with the very same rag that lays the color on and is permeated with ink.
In the second method, the wiping is harder in order to take more color away from the shallower lines, so that they will be pale compared with the deep ones which then will appear very black and strong.
If the full beauty of a well-made copper plate is to be equaled, care must be taken, as said before, to achieve the proper depth of engraving, and the stone must be wiped harder. Otherwise the method is the same, except that beautiful, s.h.i.+ning impressions often can be made by using a firm color, if the stone can bear the necessary tension.
The inking-in with the ink-roller is like the same process in other methods, except that the color must be softer and the roller well filled with it. It is necessary, also, to learn by practice how to work the color into all the deep lines.
The impression must be made immediately after inking, as otherwise the color will sink too deeply into the stone and not give a strong impression without renewed inking.
The paper must be wetted a little more than in the other method.
The tension of the press is according to the size of the plates, but on the whole must be two or three times greater than for the other methods.
More pressure still may be needed for very fine work, as the finer lines often are harder to print than the coa.r.s.e ones.
As soon as the first clean proof is pulled, it must be examined for errors or faults in the design. If there are any, the stone is removed from the press after being delicately coated with gum, and the correction is made as follows: Before anything else, all such faults as are to be removed entirely are either sc.r.a.ped away with a very sharp knife or rubbed away with a very fine stone. The manipulation must be very delicate to avoid grooves and furrows or sharp edges that afterward will hold dirt. Then the parts thus corrected are coated with a mixture of about six parts water, two parts gum, and one part aquafortis to prepare them anew.
If anything new is to be added to the design or drawn in place of an error, the stone is washed with water throughout, or, if the correction is to be made only in a very small part, washed at the desired place.
Then it is coated with the red chalk as described in the beginning, but so thinly that the design can be seen plainly through the red coat. Now all that is desired can be engraved, filled again with the rubbing-in color, and turned over to the printer, who cleanses it with gum water and proceeds to print.
Only a few more useful suggestions:--
(1) It happens often that after the first rubbing-in of fat color and the succeeding cleansing with water, the stone gets a ”tone” over its whole surface; that is, it takes color at least partly, and thus seems to have lost its original preparation. This may be due to the fact that not enough gum has been used in the original coating, or that the rubbing-in was rough enough to injure the protective coating, or that the rubbing-in-color was left on too long before being washed away with gum solution.