ENGRAVING, in its widest sense, is the art of incising designs, writing, etc., on any hard substance, such as stone, metal, or wood. Many branches of the art are of great antiquity; such as gem-engraving. cameo-cutting, and die-sinking. The more important of these ornamental and useful kinds of E. are described under their proper heads. But in a narrower sense, E. is the special designation of the art of cutting or indenting the surface of metal plates or of blocks of wood with designs, for the pur pose of taking off impressions or prints of the designs on paper. This department of the art arose as late as the 15th c., the earliest wood-engraving with a date being 1423, and the earliest dated E. from a metal plate being 1461.
Wood-engraving differs from E. on metal in this, that on a metal plate the traces or marks which are to appear on the paper are cut or sunk into the plate, and when printed from are filled with ink, while the rest of the surface is kept clean; whereas in wood engraving they are left prominent or in relief, and the blank parts of the design are cut away. Hence a wood-cut acts. as a tripe, and is inked and printed froni.ip the usual way. See PRINTING. This'makes wood-engraving peculiarly Suitable for the illustration of books; as the blocks can be printed from along with the letterpress; while the impres sions from a metal plate must be taken by themselves, and by a slow process. The fur ther treatment of the important art of wood-engraving is reserved for a separate article; our attention at present being confined to E. on metal.
It is beyond our scope to enter into the practical details of the various processes; we can only aim at enabling a reader altogether ignorant of them to conceive how the effects may be produced, and to understand the terms currently used in speaking of this kind of art.
The metals most commonly used for E. are copper and steel, the former having the advantage of being more easily worked, the latter of greater durability. The processes of working are essentially the same in both. The several manners or styles of E. are distinguished as line-engraving, mezzotinto, stippling, and aquatinta.
1. Line-engraving--in which, as the name implies, the effect is produced by a com bination of lines—is executed either by direct incision with the graver or the dry point, or by a combination of incision with etching—a chemical process to be imme diately described. The graver or burin is usually in the form of a quadrangular prism, fitted into a short handle. In making the incision, the graver is pushed for ward in the direction of the line required, being held by the at an angle very slightly inclined to the plane of the copper. A scraper is required to scrape off the barb or burr which is formed by the action of the graver and dry-point. The rubber is a roll of cloth dipped in oil, and is used to make the surface smooth. A burnisher is required to polish the plate, and erases any scratches which it may accidentally receive, and also to make lighter any part of the work which may have been made too dark. The dry-point is like a sewing-needle fixed into a handle, and is used to cut or scratch the finer lines. The graver cuts the copper clean out, the dry-point throws it up on each side; and in some cases this is not scraped off, but made use of till it is worn off, as it gives richness to the line.
In etching, the first step is to cover the plate with a composition of wax, asphal tum, gum-mastie, resin, etc., dissolved by heat; an outline of the design, made on paper in pencil or red chalk, is then " transferred " to the surface of this composi tion, by being passed through a press. The subject is then drawn on the ground with the etching-point, which cuts through it, and exposes the copper. Etching-points or needles resemble large sewing-needles shortened, and fixed into handles 4 or 5 in. long; some are made oval, to produce broader lines. A rim of wax being put round the plate, acid is poured on, and corrodes the copper not protected by the ground. If the acid is found not to have acted sufficiently, it may be applied again to the whole design, or only to portions of it, by stopping up, with a mixture of lampblack and Venice turpentine applied with a camel-hair pencil, what been sufficiently bitten in.