Techniques of Intaglio Graphics – metal scrimshaw
Copper engraving 
It is the oldest technique of intaglio graphics. Metal plate is put on a cushion and lines are cut into the metal plate using a steel tool, called graver or burin. Metal off-cuts (agnail) which stay around the lines usually are removed by sharp instrument. Depending on different strength of pressing a graver, it is possible to produce lines of different thickness and tapering off in the end. A form in the engraving is shaped by hatching. With a help of the hatching, tones are produced. After the process of line incising is finished, the plate is painted out. Later, the surface of the plate is cleaned and only the paint in the incised lines is left. The parts that have been cleaned become light tone on the impression, while the parts that have been incised and filled with paint form an image.
Etching 
Etching or aqua fortis – name is derived from French “eau-forte” which means nitric acid. It is a classical technique of intaglio graphics. An image is incised using a steel needle on a polished copper or zinc plate, which is covered with an acid resistant lacquer. Then the zinc plate is pickled with a nitric acid, while the copper plate – with a liquid iron dichloride once or a few times (in order to get lines of different intensity, depth). A master of graphics damages the surface lacquer by etching needle, therefore the incised places are etched and make a linear image on the impression with a help of acid effect. The places covered by lacquer that have not been damaged become a light tone in an image. The intensity and depth of an image depends on how long the acid etching takes place. The longer period the plate is dipped into the acid, the more intensive image is gained. When the lacquer from the plate surface is cleaned, places that have been etched with an acid are covered in paint and the impression on a damp paper is made. Etching technique is often combined with aquatint, soft ground, copper engraving, and drypoint techniques in order to accentuate the variety of tones. The technique dates back to 17th century. Etching can be recognized from a free line drawing, dark and bright tone composition, and delicate line-drawing.
Drypoint 
It is another technique of intaglio graphics, which became popular in the 20th century. Lines on an image are scratched directly into a plate using a sharp needle, called the drypoint needle. Where treated with a needle, rough metal edges are thrown up. Those edges are not removed before the printing process. Some are removed only in certain places. They give additional intensity and softness for a line. Till the 19th century drypoint technique used to be combined with other techniques (most often with etching). It was due to the use of copper for making impressions, which is a soft metal. This metal looses its rough metal edges rather quickly during the repeated process of printing and the image that is being made looses its expressivity, which should be characteristic to this technique.
Mezzotint 
Mezzotint – in Italian mezzotinto < mezzo – middle, in-between + tinto – painted. It is another technique of intaglio graphics, which allows creating a work of art using light and soft intermediate tones. The surface of copper or steel plates is completely marked with a dense network of lines, made with ragged steel instrument, called a rocker. Then the places, which should not be touched by paint for them to be light on the impression, are polished. Depending on the lightness of the tone, the cliché is smoothed or completely polished accordingly. The technique was invented by self-educated German artist Fon Siegen, who has admired the art of painting and has been looking for an appropriate way to reproduce it. Mezzotint is different from drypoint engravings the way that gradual light and shadow transitions dominate the lines. This is one of many techniques of graphic art invented in 17 – 18 centuries for reproductive purposes. The basic process of making an etched engraving consists of chemical treatment of the incised printing form.
Aquatint 
Aquatint – from Italian “aquatinta” which means “coloured water”. It is another technique of intaglio graphics, which was begun to use in the middle of 18th century. It is a variety of aqua fortis technique, which is used to create different tonal qualities and intensities. The same printing forms that are used for aqua fortis are used for aquatint as well. The places that have to be darker on the impression are covered in wax or resin (galipot, asphalt, etc) powder, which stick to the surface when the printing form is being heated. The acid is spread over the plate and bites into the tiny holes between grains. This way a rough surface is created, which becomes a smooth tonal mark on the impression. In order to achieve a variety of different tones, certain places of printing form are glazed once again and the process of etching is repeated. The more times it is repeated, the wider variety of tones appears. A composition of aquatint and aqua fortis is widely spread in graphic art. The technique of aquatint was designed by the world famous artists, including Francisco Goya, Louis Philibert Debucourt.
Soft lacquer 
It is a technique of intaglio graphics, a variety of aqua fortis. The works made using this technique remind of drawings with a pencil. An ordinary lacquer used for aqua fortis is supplemented by grease in order to make it softer and easily recoiling from metal printing plate. The glazed printing form is covered with paper, on which an artist draws with a hard and obtuse pencil. The pencil being pressed, the lacquer sticks to the paper and when it is removed the lacquer resiles from the metal plate. With the help of acid etching, intense, grainy lines and spots are achieved.