Engraving while process of incision on a surface to obtain aesthetic effects has existed since pre-History, but takes on a new breath after the 2nd half of the 15th century with the use of this technique to create a matrix that would make possible the multiplication of that same image, accompanying from then on the history of the printed image. In pre-History the engraving technique can already be considered to have existed since the meanders traced on clay to the points, parallel or crossed lines left on the bone plates or even in the anthropomorphism and / or animalist representations carved in the rock, as in the case of the horses and cattle of Foz Côa (Fig. 1).
In Europe, from the 2nd half of the 15th century, engraving denominates the image that is obtained from a matrix in which, through the diverse procedures – xylography, deep engraving, planographic - , it is able to obtain various reproductions of the same image. In the 15th century the possibility of reproducing an image revolutionised the ability of communication between people. Doctors had access to illustrated books with all the anatomical parts of the human body. Military engineers bought treaties with engravings of forts, castles and respective topographical marks. Artists from all over the world were inspired in the various illustrated editions of the Metamorphosis by Ovid as a model. However, it was precisely the possibility of multiplying that impeded Engraving from being considered an art in its own right (v. Visual Arts), a recognition which was only received in the 20th century. Nevertheless, right in the 16th century, great artists like Durer, Cranach, Holbein and Lucas van Leyden, approached engraving, even if most of the times they had limited to making the design and monitoring the execution of the engravers.
In Portugal, the first Engraving Lesson was only created in the 2nd half of the 18th century and had as its first director and master Joaquim Carneiro da Silva.
The first engraving technique that is known was xylography – engraving in wood with the design in relief - , but quickly one resorted to other metallic matrix processes, due to their high quality, but especially because with the increasing number of copies, the wood matrix became inoperative. Today, with all the technological means at our disposal, it no longer makes sense to reproduce images via engraving, which only left its affirmation as a form of artistic expression.
Each artist chooses, among a variety of Engraving techniques, one certain technique, or more than one – mixed engravings - , according to the result intended because each technique originates a specific graphic register.
In xylography, the artist or craftsman will make the image emerge in relief, carving with a penknife, preferably soft wood like mahogany, pear tree, apple tree, walnut tree, whereas when the burin is used he favours box wood. The other process in which the image appears in relief is the engraving of the metallic matrix by the stippling process, in which the ink passes onto the paper through these raised parts left by the roulette or by puncture, with which different tones are obtained. This method was used the most by Francesco Bartolozzi (1727-1815), fundamental figure of engraving at the end of the 18th century who stayed in Portugal after his acknowledged career in England (Fig. 2).
In deep engraving, the opposite of woodcut and of engraving on metallic plate by stippling, the image is carved into the metal matrix and it will be in these grooves that the ink penetrates, and after, through processes of considerable mechanical pressure the ink is transferred onto the paper.
All the processes that use a metallic matrix, usually of copper, require a covered plate with varnish, and after the engraved image using a burin or other tool, the mordant (acid) is applied to the plate, like engraving by the stippling process, etching and aquatint and some of the so-called mixed. The exceptions are the engravings of metallic matrix called “intaglio” and “drypoint”.
In intaglio engraving, on the metallic plate covered with varnish the engraver draws on the varnish, after he opens the metal with a burin, takes off a layer of varnish and the matrix is ready for impression in the printing press. Drypoint engraving, also carried out on a metallic plate, constitutes a more direct engraving process that exists because it does not need mordant and varnishes as intermediaries. It is different from the intaglio engraving because it does not need the varnish. That is why, when the engraver opens the metal with a needle the burrs are lifted at the edge of the line that leaves a particular effect when printing. This plate has an inferior durability than the rest because at the end of fifteen or twenty copies, the matrix is worn out.
In the engraving techniques with a metallic matrix that use mordant – etching and the aqua-tint – the design emerges from the corrosion of the artist’s lines by the use of some corrosive liquids.
Etching is the only one that exclusively results from the corrosion by the acid, being a technique that generates an image with all the spontaneity of the drawing. Because it is a totally indirect technique, the artists many times would combined it with the drypoint technique.
This designation “strong-water” (etching) comes from the fact that the plate is immersed in mordant diluted in water that corrodes the areas in which the engraver removes the wax or varnish. This, after the plate has been covered with a thin layer of wax or varnish, in which the image was opened with a needle or burin and after protecting the back and sides of the plate with Brunswick black. This was one of the techniques most used by the great artists from Rembrandt (1606-1669) to Goya (1746-1828), such as in Goya’s series Los Caprichos.
In the second half of the 18th century, aquatint engraving is first introduced by the inventive Jean-Baptiste Le Prince (1734-1781). In this new process, the metallic plate instead of being covered with varnish or wax, it was coated with a resin and alcohol solution; the evaporation of the alcohol contracts the resin that ends up cracking, leaving behind a number of grains stuck to the metal; in another procedure, the plate is covered with sprayed resin to obtain the same effect. The engraver drew on this preparation and dipped the plate after in the mordant that would corrode the areas from which grains of sand had been lifted. An engraving results from this technique with different tonal areas of greys and not with lines like the xylography. The aquatint technique was immortalised by great artists of the Impressionism and Modernism like Edgar Degas (1834-1917), Camille Pissarro (1830-1903), and Pablo Picasso (1881-1973).
This chalcographic technique (whose method of matrix production implies the action of chemicals) resulted from the will to simplify the mezzotint engraving. In this technique the granulated effect was achieved, not through the grains of sand, but through perforating the metallic plate with a roulette or with a blade with teeth, after having the engraver to polish the areas that in the printed image should be clearer.
The coloured engraving was also used by various artists since the 2nd half of the 17th century. For example, the Dutch Johannes Teyler (1648-1709) and Peter Schenck (1660-1713) hand tinted the copperplate. Using aquatint engraving or mezzotint an effect identical to pastel painting is achieved in the print, by using, however, as many copperplates as desired tones in the final print, like Bonnet and Boucher did.
Engraving played an important role in the Visual Arts. It was with the possibility generated by the engraving of many images that the images of saints were disseminated throughout all of the Christian civilization, that labels, maps, decks of cards, illustrated editions of Ovid, images of Classical Rome, anatomical studies of the human body in medical books, amongst other images, reached the four corners of Europe and were disseminated by inter-civilizational contact areas, like what happened, in the age of the discoveries, in the Jesuit missions of India and China.