THE COPPERPLATE-PRINTER.
1. The copperplate-printer takes impressions on paper from engraved plates by means of a rolling press. This machine, together with some of the operations in its application, are well exhibited in the above picture.
2. The period at which the practice of printing from engraved plates commenced, cannot be ascertained with any degree of certainty. The Dutch, the Germans, and the Italians, contend for the honor of introducing it; but the weight of testimony seems to be in favor of the claims of the Italian sculptor and goldsmith, Tommaso Finiguera, who flourished at Florence, about the middle of the fifteenth century.
3. It is stated that this artist, accidentally spilling some melted brimstone on an engraved plate, found, on its removal, an exact impression of the engraving, marked with black, taken out of the strokes. This suggested to him the idea of taking an impression in ink on paper, by the aid of a roller. It is hardly necessary to state, that the experiment succeeded. Copperplate-printing was not used in England until about 150 years after its first employment at Florence, when it was introduced from Antwerp, by Speed.
4. The ink used in this kind of printing is made of a carbonaceous substance, called Frankfort black, and linseed or nut oil. Oil is used, instead of water, that the ink may not dry during the process; and it is boiled till it has become thick and viscid, that it may not spread on the paper. The materials are incorporated and prepared with the stone and muller, as painters prepare their colors.
5. In taking impressions from an engraved plate, it is first placed on an iron frame over a heated stove, or over a charcoal fire in a furnace, and while in this position, the ink is spread over it with a roller covered with coarse cloth, or with a ball of rubber made of the same material, and faced with buckskin. The heat renders the ink so thin that it can penetrate the minute excavations of the engraving. The plate having been thus sufficiently charged, is wiped first with a rag, then with the hand, until the ink has been removed from every portion of it, except from the lines of the engraving.
6. The plate is next placed on the platform of the press, with its face upwards, and the paper, which has been previously dampened, is laid upon it. A turn of the cylinders, by means of the arms of the cross, carries the plate under a strong pressure, by which portions of the paper are forced into all the cavities of the engraving. The ink, or part of it, leaves the plate, and adheres to the paper, giving an exact representation of the whole work of the artist. The roller by which the pressure is applied is covered with several thicknesses of broadcloth.
7. The number of good impressions yielded by engraved copperplates, depends upon various circumstances, but chiefly on the fineness and depth of the work; and these qualities depend mainly upon the style in which it has been executed. Line engravings will admit of four or five thousand, and, after having been retouched, a considerable number more.
8. Plates of steel will yield near ten times as many good impressions as those of copper, and this too without being hardened. Besides, an engraving on steel may be transferred to a softened steel cylinder, in such a manner that the lines may stand in relief; and this cylinder, after having been hardened, may be brought in forcible contact with another plate, and thus the design may be multiplied at pleasure.
9. The bank-note engravers have now a great variety of designs and figures on steel rollers, which they can easily transfer to new plates. This practice, as applied to plates for bank-notes, originated with Jacob Perkins. It is supposed that he must have been led to it by an English engraver in his employ, who may have explained to him the manner in which the British calico-printers produced engravings on copper cylinders. This is not altogether improbable, since the principle in both cases is substantially the same.
10. In consequence of the increased demand for maps and pictorial embellishments in books, as well as for single prints as ornaments for rooms, engraving and copperplate-printing have become employments of considerable importance; and these arts must doubtless continue to flourish to an indefinite extent, in a country where the taste for the fine arts is rapidly improving, and where wealth affords the means of liberal patronage.
