Engraving

Engraving is an artistic technique, via which an engraved printing plate, which is then inked and pressed on pieces of paper using rollers and presses, a series of examples can be produced, a limited run of the same image, a chalcographic print.

On the printing plate, the engraver may intervene later, effecting print trials, and trials of state. The engraving planned and executed by the same artist is said to be original, in the case in which the executor is different from the planner it is said to be translated.

According to the execution and printing technique, two principle engravings are to be distinguished, relief carving and hollow engraving.

In relief carving the printing plane is worked with particular instruments, chisels, engraved so as to leave exposed the parts that define the image.

The ink is lain out with a roller or a dabber on the elevated part of the printing plate. The print can be carried out manually placing the printing plate on the paper, or placing the paper on the printing plate and rubbing a hard smooth object, or pressing vertically with a typographic press. In rilief engraving, the printing plate can be made of wood, xylography, linoleum, linoleum printing or lino printing or other adapted materials.

In hollow engraving, the engraved printing plate holds the ink into the grooves and leaves it on the paper when printing.

The printing plate can be engraved directly by hand, using the appropriate instruments, burin, dry point, mezzotint and with stamp, or indirectly, using an acid. The corrosive action of the acid, engraving, corrodes the metal points left uncovered by the drawing traced on the plate previously recovered from a layer impermeable to the acid engraving, acquatint and soft paints.

The colours

Engravings can also be printed in colour.

Generally, in techniques like etching, silk-screen printing, xylography, linoleum printing, the colour is applied using various molds (matrici), colouring the same mold (matrice) with different colours.

In the first case, each matrice is used to print a single colour, which is applied with a certain sequence and only in particular points, for which the final image will be given by the fusion of various colours, applied each time with a different matrice, for example in silk-screen printing.

Another system consists in starting the process of colour printing with a single empty or almost empty matrice. This technique is usually used in linoleum printing and in xylography. The matrice, in this case a block of wood or a sheet of linoleum, initially smooth or little engraved, is inked for printing the first colour, the matrice is subsequently cleaned and engraved again in a more extended way, inked in a different colour from the former and the printing of the same surface is executed.

With printing techniques like monotype, the artist can paint the colours directly on the matrice and then print.

Etching

The term indicates both the type of printing and the method used to produce it.

It is an indirect hollow engraving technique that consists in corroding a sheet of metal, usually zinc, with an acid, to extract images to transfer onto a base, normally paper, using colours. The surface of the plate is cleaned and softened at its edges with sandpaper, then degreased on its shiny side with cotton wool dampened, for example, with bianco di Spagna, calcium carbonate, dissolved in water. Once shiny it is spread in an even manner with a thin layer of wax for etching or a wax based covering to isolate the surface from the acid, it is then blackened, that is smoked with candle black smoke, to render the surface more resistant to the acidic action and the marks more visible.

With a thin steel point the marks that appear on the image are engraved, in the protective material, in freehand or tracing a sketch on white tracing paper, exercising sufficient pressure to uncover the metal in correspondence to the marks that appear on the paper thanks to the ink. After having spread with a covering material or sticky tape the back side and the edges, the plate is immersed in a bowl containing acid, usually nitric acid, starting the acidation, which can be done several times uncovering in succession the parts to be etched, to obtain grooves of differing depths. The sheet must remain in acid for a time proportional to the type of mark desired, the longer the corrosion lasts, the darker the print will be.

When only one immersion is performed in the acid, the etching is called soft or “piana", the engravings all have the same force; the chiaroscuro and therefore the different tones are determined by the crosses and lines that are either closer or further away.

When the immersion occurs in several moments the etching is called by covering or "per coperture" that is the plate is acidified a first time, then the marks which should result as being thinner and lighter in the print are covered with a protective paint, then the plate is immersed again to obtain thicker marks, and the operation is repeated until the marks are wider. The clear limits in the print will appear between the various areas with different etchings.

When the marks which must appear more strongly in the print are initially acidified on the plate, and must subsequently be added, after each etching, the engravings which must be thinner, we have the added or "aggiunte" etching. This procedure creates differentiated engravings, and blended soft passages, given the opportunity to intervene in any moment and in any part of the work right up to the completion of the etching.

Once the plate is considered complete, it is cleaned with petrol or turpentine and dried. The matrice ready for printing, is covered in greasy ink with a leather cloth and heated on a hot plate to favour the absorption of the colour in the grooves and its transfer to the paper. After its removal with a cloth, and then with the palm of the hand, of the excess ink from the parts that must be white on the sheet, we proceed to the printing which occurs with a chalcographic press on paper which has been slightly glued and previously dampened.

Etching is characterised for the variety of engravings and for the chiaroscuro effects that can be obtained.

Aquatint

Aquatint is an indirect carving technique similar to the etching procedure, in that the corrosion takes place through the use of acid, but it varies in the preparation of the printing plate.

With the aquatint procedure it is possible to create effects similar to water colour. Together with other techniques, it is the favourite method to colour print.

It is a technique which is tonal in character, the image is realised using areas of controlled form and intensity. The intervention occurs on a printing plate with a special treatment that corrodes the surface of the plate determining roughness that maintains the printing ink, the graining.

The granulation is effected dropping granulose substances onto the plate, heated on a hot plate, powdered Greek tar, marble powder or sugar that melt attaching themselves to the surface forming a bottom that is more or less dense.

When the plate, protected with anti-acid paint on the back and on the sides, is immersed in the acid, the grains contained in the wax, being porous, allow the infiltration of liquid in all the cracks of the various grains, which produces a light corrosion on the surface, which appears spongy.

On printing, this “roughness” is able to maintain the ink and therefore different grades of colour in the various parts of the composition can be achieved using subsequent etchings and coatings.

With this method, subtle silky effects and a rich series of blended grading are obtained in the printing phase.

Once the sheet is regarded as complete, it is cleaned with petrol or turpentine and dried. The plate ready for printing, is coated in greasy ink with a leather cloth and heated on a hot plate to favour the absorption of the colour in the grooves and its transfer to paper. After the removal of the excess ink with a cloth, and then with the palm of the hand, from the parts that must result white on the paper, we proceed to the printing which takes place using a chalcographic press on slightly glued previously dampened paper.

Dry point

Dry point is a hollow engraving technique with which, to obtain the matrice, metal is engraved directly, without using acids.

Generally the matrici are sheets of copper or zinc, but it is also possible to use Plexiglas, which, besides being softer compared to sheets of metal, for its transparent quality allows the result of the engraving to be seen immediately without proceeding to a trial print.

It is the most simple of all techniques. You draw on a blank surface, con with a soft pencil or with ink, then, with a steel point, the sheet is scratched engraving it with appropriate depth.

A sharp, cutting, robust pointed steel tool is usually used, with a wooden handle or a diamond point.

With differing pressure exercised on the point the variation in depth is determined and therefore the width of the groove, which then printed, will give a more or less intense mark.

Exercising pressure on the sheet to trace the mark, the point penetrates the sheet, moving metal filaments, like drops, called “barbs”, onto the sides of the groove which capture the ink, and in the printing phase as a result give a little wide and blended line, a silky mellow mark characteristic of this technique.

The scraper, with a triangular blade, sharpened to a point, is used to slowly take away the useless “barbs”.

Given the difficulty in manipulating the point, especially in the curves, for its tendency to slip, the mark will be made up of a series of light lines marked close together, rather than a single robust stroke. It can also be sketched lightly and then given more detail with several revisions. For more delicate markings or layers in chiaroscuro the diamond point is used.

One of the most characteristic aspects of dry point is the unmistakable nature of its markings, both for the presence of the “barbs” and for the blackish halo tinged in the first run, both for the movement of the markings, often irregular in size and direction.

The “barbs” are removed or squashed during the cleaning of the sheet or under the pressure of the press, so the marking diminishes in strength after the printing of a few copies.

For these characteristics, dry point is adapted only for limited runs, as an alternative acciaiatura, an electro-chemical process which increases the resistance of the matrice, can be used.

A technique connected to dry point is "mechanic point," in which different points and pressures are used to obtain various effects using a small drill.

Once the picture is completed, the matrice, previously heated on a hot plate to favour the penetration of the paint in the grooves, is inked with a leather dabber then cleaned well with the palm of the hand and with the help of a cloth.

The print is executed on damp soft paper, placed on the sheet and then passed under the press roller of the printer. The pressure of the roller causes the inking of the paper which, being soft, sinks into the grooves of the drawing and absorbs the ink. In this way the drawing passes from the matrice to the print.


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