The preferred metal for engraving plates is copper, which is easily incised, yet strong enough to withstand repeated passes through a press under pressure. Silver, zinc, steel and plastic plates are also used. Metal plates can also be steel- or chrome-faced by electrolysis. This protective layer, consisting of a microscopically thin coating of a stronger metal, is useful in large editions, in which the line quality gradually deteriorates. Since the 1950s some artists have engraved on transparent plastics, with the advantage that a drawing placed underneath can be seen.
Specialized engraving tools are used, and each has a characteristic cut that produces a distinctive printed line startend. The graver or burin (1a-d) is a steel shaft, square or lozenge in section, mounted in a rounded wooden handle. Burins come in a variety of sizes. The end of the shaft, which can be straight or bent, is sliced off at a 35–45° angle. The resultant line has an innate formality resulting from the method of cutting. The engraver holds the tool with the palm of the hand, low to the plate, and cuts straight ahead, turning the plate against the tool as the line curves. The burin is capable of a range of strokes, from the most delicate to rather wide, depending on the pressure exerted. As the tool moves in a V-shaped cut, it produces a curl of metal ahead of the engraver; the line swells and tapers according to the depth of the cut and whether the graver is held straight or is rotated to the side. The end of a line appears to come to a point. If the cut is not absolutely clean, a sharp burr remains, which is generally scraped away. Burr left along the line will hold ink and adds richness to the print. This richness is characteristic of the earliest impressions from a plate, for burr will soon be flattened by repeated printings.
Other tools used for engraving include drypoint needles or scribers (1e) for lightly scratching the design on the plate; and compasses and dividers for measuring and scribing. Tools for producing tones and textures include stipple gravers (1c), burin-like tools with curved shafts; multiple lining tools (1d); roulettes (1g-h), tools with small wheels that perforate; mattoirs (or mace heads), whose end has irregular points, and mezzotint rockers (1i), which have curved blades with serrated edges. Machine oil and good whetstones are necessary to maintain the sharpness of engraving tools. The engraver also uses files for bevelling the edges of the plate, scrapers and burnishers, callipers, hammers and pumices and fine grits for correcting errors. Many engravers rest their plates on a leather cushion or ball to assist in turning the plate. Some engravers use magnifying lenses or eyepieces, worn on a headband or supported by a stand.
The design for an engraving can be transferred from paper to a plate in a variety of ways. One method is to rub the verso of a drawing on paper with chalk. The plate is then coated with wax or asphaltum, or carbon paper can be placed between a drawing and the coated plate. A scriber is used to retrace the outlines of the drawing, imprinting a transferred line on to the plate in the same direction as the original drawing. The resulting print will be a mirror image of the original drawing. A second method enables the engraver to produce a print in the same direction as the original drawing. The plate is coated with wax or asphaltum, and a soft graphite drawing or ungummed ink on a smooth surface such as tracing paper is placed face down on the plate. The drawing is either rubbed or run through the press, and the transferred drawing prints in reverse on to the plate. After engraving, when the plate is printed, the impression is in the same direction as the original drawing. Ungummed-ink transfers to engraving plates were used as early as 1605.
During the course of the engraving process, engravers often print trial prints or ‘proofs’ to show the progress of the work, and these can be drawn on to explore alternatives for further engraving. A counterproof (a print made from a freshly printed proof) is sometimes made to reverse the reversal of the original design.
Papers for printing engravings must be able to be soaked or dampened to remove the sizing and relax the fibres, and be strong enough to withstand the reshaping of the sheet under pressure without tearing. Lightweight, translucent, laid and heavier opaque mould-made papers are suitable. Evenness of pulp is desirable, and coloured papers have often been used. Paper is an important factor in the appearance of an impression. Alternatives to paper, used especially in the 19th century, include satin, which is extremely receptive to the printed image, and silk. Decals printed with ceramic inks from engraved plates have been transferred to porcelain and fired, fusing the ink into the glaze. In the 20th century S. W. Hayter introduced the process of printing engraved plates by casting them in plaster.
Printing inks are prepared from well-ground pigments that are worked into reduced linseed oil (burnt-plate oil) until the mixture is very stiff and well saturated with pigment. Both black and coloured inks are used. It can take a week or more for oil-based inks to dry. Additives used in modern commercial inks include driers, varnishes and fillers. Solvents for cleaning include paint-thinner and turpentine; some formerly used, such as benzine, are now banned as health hazards.
The plate is inked with one of a number of devices for spreading it across the surface and forcing it down into the lines. An inking ball of leather or a poupée (a cylinder of tightly wound felt) are traditional, and brayers and squeegees are often used today. Fabrics, such as stiffly starched mesh, called ‘tarlatan’ cloth, and newspaper are used to wipe the surface. The printer can wipe the plate’s surface perfectly clean or leave a film of plate tone either all over or in selected areas. Wiping is finished using the heel of the hand with whiting ( calcium carbonate). Multiple colour prints are made using separate plates for each colour and printed wet on wet (to avoid registration problems arising from paper shrinkage) or à la poupée, that is all the colours carefully applied and blended on a single plate.
The press used for printing engravings consists of a structure that supports two heavy cylinders arranged horizontally, one above the other, separated by a flat pressbed that moves horizontally between them. In modern presses the cylinders are attached to powerful springs that are tightened by pressure screws. A flywheel drives the cylinders either directly or by means of gears. Formerly presses were built of wood, but since the 19th century they are of cast-iron or steel; since the late 20th century plastic laminates have also been used.
The wiped plate is placed face up on the press bed, and dampened, blotted paper laid on top of the plate. Felts (blankets) are placed on top of the paper, and then the bed passes between the rollers, forcing the paper into the inked lines. For each impression made, the plate must be re-inked and wiped.
engraving can combine in the same plate with any other of the intaglio methods such as drypoint, etching, mezzotint and aquatint. Since engraved plates are printed by intaglio, they cannot be printed simultaneously with cast type in the same printing run. Early illustrated books were illustrated by relief-printed blocks and metal plates, but in the 16th century engraved metal plates were recognized as having greater endurance, finer detail and greater ability to show certain pictorial effects of atmosphere. By the second quarter of the century engraving and typography were routinely combined in books and single sheets printed by means of two different presses. In the 20th century experimental printmakers began combining engraving with woodcut, lithography, serigraphy and monotype printed on the same sheet.
A tradition of signing and inscribing titles and publishing information has grown up with engraving. Early engravers used a hallmark or monogram and later personal names, sometimes inscribed in a plaque or tablet within the image. The work of producing an engraving was divided among specialists, and the artist, engraver, printer and publisher were frequently different individuals. By the 16th century an inscriptional space was frequently left on the lower edge of a plate, where a variety of customary Latin words and phrases were used to identify the work and claim rights of publication: the artist invenit (invented), delineavit (drew) or pinxit (painted) the image; the engraver sculpsit (engraved) or fecit (made) the plate; the publisher excudit or divulgavit (published) the print, often cum privilegio (with the permission and copyright protection) of a governmental authority for a certain period of time. Works were also frequently D.D. (dedicated) to some valued patron. The engraving of lettering was a speciality and was often done by someone other than the pictorial engraver. The idea of limiting the size of editions arose in the 18th century, and the custom of autographing original prints in the lower margin outside the platemark began in the 19th century, as did the concept of artist’s proofs. The practice of fractional numbering of the impressions in an edition (for example, ‘3/50’, i.e. third impression of an edition of 50) began c. 1900.
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