Etching
An etching is a print taken from a sheet of metal, usually copper, zinc or steel, into which the image has been bitten with acid. In a line-etching the metal plate is first covered with an acid - resistant “ground”. The artist draws the image through this ground, thus exposing the metal surface, and then immerses the plate in an acid bath. The acid etches away the unprotected metal, creating lines which hold ink. The artist may use different effects, but always relies on the acid to etch the plate.

An etching is an “intaglio” print ( from the Italian word meaning to carve or incise). An intaglio print is printed on an etching under tremendous pressure, so that the dampened paper is actually forced into the inked lines and textures of the plate. Other types of intaglio prints are engravings, drypoints, line-engraving and mezzotints.

Drypoint
Drypoint is a method of producing an intaglio print by simply scoring the plate with a steel point, pulled across the surface towards the engraver. The tool displaces (rather than removes) the metal, raising a ridge alongside each furrow. The ridge (called a burr) retains ink when the plate is wiped after inking, and prints a characteristically soft, velvety line. Due to the friction of the inking and wiping process and to the pressure of printing, the burr of a drypoint begins to flatten after a few impressions.

Mezzotint
In mezzotint the surface of the plate is evenly and systematically roughened all over with a rocker (a tool like a chisel with a short, broad blade whose cutting edge is curved and serrated; The dense texture raised by the rocker would, if inked, hold so much of the pigment that it would print solid black. The engraver proceeds from this black to the lighter tones by smoothing the surface of the plate with implements known as scrapers and burnishers. The areas left roughest retain most ink and thus print blackest; those polished smoothest retain little or no ink and therefore provide the highlights.

Aquatint
Aquatint is so called because plates etched by this method produce prints with the effect of watercolour. The polished plate is sprinkled evenly with resin or asphaltum, either by hand (through a muslin filter) or in a specially constructed box in which the powder is agitated and then descends like a light snowfall onto the plate. The plate is heated until the grains of resin or asphaltum melt and adhere to it in tiny globules. On immersion in acid, the areas of metal exposed between the globules are attacked or ‘bitten into’ and the required image is produced by successive immersions. Between these immersions, biting is controlled by stopping out appropriate areas of the plate with acid-resistant varnish. Areas bitten for the shortest time produce the palest tones; those bitten longest, and therefore more deeply, print darkest. Globules and varnish are removed with solvents before printing takes place.

Relief Printing
A method in which the artist using knives, gouges, or electric tools, cuts away the areas of a piece of wood or lino that are not for printing. Ink is rolled on the ridges and the areas left standing. The ink is applied by using a pad or roller. the paper is laid on the block and the image is transferred either by using a press, or by “burnishing” (rubbing) the back of the paper with a baren or wood spoon. the terms woodcut, wood engraving, linocut and relief etching describe different types of relief prints.

Screenprints
Screenprints, also known as serigraphs or silkscreen prints, are printed using a screen made from a very fine fabric, originally silk, stretched over a frame. the non-printing areas are blocked off with a filler or a stencil using a handpainted or photographic image; the open areas of the mesh will print the image. The paper is placed beneath the frame and the ink is pulled along the screen with a rubber blade called a” squeegee”. The ink passing through the open mesh of the screen is deposited onto the paper below.

Lithography
A lithograph is printed from slabs of Bavarian limestone, or more recently from zinc or aluminium plates. The artist draws or paints the image on to the stone using a greasy crayon or ink. The stone is chemically treated to fix the image. In the printing of a lithograph, the stone is dampened and the ink is rolled over it; the greasy areas of the image attract the ink while the damp areas of the stone repel it. The paper is laid on the stone and pressure is applied by means of a lithographic press; thus the image is transferred to the paper.

Monoprint
The monoprint or monotype is often thought of as a halfway stage between painting and printmaking. The process is simple: the artist paints, rubs, or wipes the design directly onto a plate, using a fairly slow drying paint or ink. The fleeting image must be printed before the ink dries. Printing may be by press or by hand, and as the name monoprint implies, one can usually get only one strong impression. The effect must be guessed right from the start; there will be no trial proofs or different states unless the design is redrawn for a second impression. This term is used to refer to any print made in one version and incapable of being repeated. A monoprint cannot be editioned.

Monoprinting does allow the artist unusual freedom and spontaneity.

Carborundum
The artist mixes together carborundum( finely ground metal particles) and a strong glue into a paste. Using a brush, the required image is then painted or drawn onto a plate of perspex or metal with this paste. This will dry and harden within a day. Etching inks are then applied to the plate and it is wiped and printed as a normal etching would be. The gritty texture of the carborundum will hold ink to the degree with which it has been applied. The carborundum technique is often combined with drypoint, where lines are scratched into the plate.

Collograph
A collograph, which is derived from the french word “coller” meaning “to stick”, is the printed result of a variety of materials glued together, on a base, (usually made of metal or card). This is then inked up and printed as a combined etching and relief print.

Polytype Technique
The Polytype Technique, a method of producing copper graphics, was refined and perfected by Swedish printmaker Peter Sjoblom. Although it is a technique first discovered in the nineteenth century, due to its complexity, much of the work produced using this method is experimental in nature.

The basis for the development of the technique is electrolysis. Throughout the nineteenth century there were many attempts, with varying degrees of success, to translate the electrolytic process into a method of producing copper graphics of a more painterly aspect. Peter Sjoblom’s knowledge of modern electrochemistry led him to believe that successful resolutions to these old problems could be found. The process works on the premises of creating a magnetic field of energy by using a solution (copper sulphate) dissolved in water. When the sulphate dissolves it releases positively charged copper ions and negatively charged sulphate ions. When an electric current is passed through the solution, the ions begin to move. The positively charged ions migrate towards the negatively charged plate and the negative ions towards the positively charged plate.

Through various experiments Peter Sjoblom discovered that the most reliable material to use for the plates was silvered copper. The picture is painted positively, exactly as it is to turn out, and then treated with special mixture of graphite. When the picture is submerged in the copper sulphate solution and the current is passed through, the copper migrates from the positive electrode and is deposited in a layer over the surface of the picture. Thus a new plate which is a mirror image of the painted picture is created. This plate can be printed like an ordinary intaglio printing plate, and many impressions can be taken from it, hence the choice of name for the new technique “Polytype” (Greek pol’ys - many, typ’os - impression / picture)

These experiments were carried out in the intaglio printing workshop Atelje Larsen in Helsenborg, with the help of Ole Larsen. To test the potential of these techniques Peter Sjoblom invited 8 Nordic artists to join him from October 1988 to April 1989. He deliberately chose painters whose experience would not be influenced by previous encounters with copper etching.