The term intaglio refers to many different techniques including drypoint, engraving, mezzotint, etching, aquatint, sugar lift, soft ground, spit bite, and photogravure. It is an extremely versatile medium that suitable to many different kinds of artistic personalities. It is characterized by rich tones, a tactile surface and a "plate-mark".

The basic premise of intaglio is that incisions, depressions and recessed areas are marked into a plate of copper, brass, iron, zinc, or even plastic. This can be done in many ways, including "dry methods" like engraving and drypoint and "wet methods" which involve using acids to etch the marks into the plate. Ink is deposited into the recessed areas of the plate, and the surface is wiped clean.The ink in the recessed areas of the plate is left behind.

The plate is put into a special press and overlaid with dampened paper. The dampness of the paper makes it both more receptive to the ink and softer so that it can be pressed into the incised marks.A cylinder puts pressure through several layers of felt blankets and the damp paper is pressed into the recessed areas of the plate. As a result, the paper picks up the ink.(see also fig.6) An intaglio print is recognized most easily by the resulting impression of the plate into the paper. This is called a "plate mark".A cylinder puts pressure through several layers of felt blankets and the damp paper is pressed into the recessed areas of the plate. As a result, the paper picks up the ink.(see also fig.6) An intaglio print is recognized most easily by the resulting impression of the plate into the paper. This is called a "plate mark".

Dry intaglio processes are markmaking/drawing processes for intaglio that don't involve etching (acids). This means that the recessed areas of the plate that hold the ink are created using tools. These tools can be traditional tools like a burin (engraving) or electric power tools. Even with traditional tools, the possibilities are enormous.
A drypoint intaglio mark is created with a scratching tool like a carbide or diamond tip tool. As the tool scratches along the surface of the plate it raises a bur of either side of the mark. When the plate is inked, the bur and the shallow mark hold ink. The marks of a drypoint are very distinct. They are velvety and soft, and can be very dense when inked properly. The hardest part of working with drypoint is wiping the plate. It is difficult to keep the ink on the plate when wiping and even harder to keep the plate from losing its bur. The relative delicacy of the drypoint image on the plate means that few proofs are pulled and edition sizes are small. A highly skilled master printer can get around 50 prints without losing too much of the image whereas a person with less finesse could quite possibly get only one before the plate breaks down. When printing, tarlatans and other rough wiping implements should not be used and hand wiping the drypoint plate will cause less wear on the delicate burrs. Copper is the most suitable plate material for drypoint because of its hardness.

Engraved lines are very sharp and clear. The burin cuts the plate and when there is a bur, it is removed. Engraving requires a lot of skill and makes beautiful lines. Unlike drypoint, it is stable and easier to print.
Mezzotint is similar to dry point in that they both utilize a burr to hold the ink. However, they look very different. The mezzotint plate is traditionally marked over its entire surface with a mezzotint rocker. This tool raises a uniform burr on the plate. If the plate is inked at this point, it will be completely black. The artist then uses a series of tools (scrapers, and burnishers) to put the white tones into the plate. The result is a soft tonal image with very rich black tones.
The scraper and burnisher are the "erasers" of intaglio. I consider these to be important drawing implements and are essential tools for anyone who wants to learn intaglio. It is important to understand the subtractive possibilities of intaglio in terms of developing images and beginning students of intaglio are often given an assignment of developing multiple images on the same plate. The metal plate can be worked and etched and scraped over and over until there is no longer any metal left! It still prints nicely (because of the felt blankets) and the surfaces seem to get richer the more work that is done. I know an etcher who has been using a plate over and over for 16 years!

Wet intaglio processes are ways of markmaking/drawing for intaglio that use etching (acids). This means that the recessed ink holding parts of the plate are etched using acid.
There are many ways that a plate can be etched and each method has different results. The most common techniques are "line etching" and "aquatint". Image: close up of zinc and copper plates

There are many ways to get marks onto an etching plate. Especially with photographic processes the possibilities are really endless. Here however, we will just be discussing the two basic forms of line etching versus aquatint.
Line EtchingThe first etchings were made using basic drawing tools like an eschope or an etching stylus to scratch away an acid resistant ground from the plate. This would expose the plate material.
The plate would then be put into an acid bath which would etch the plate only in the areas that had been scraped away. This would leave the lines etched below the surface and ready to hold ink for printing.
AquatintLater, a process that is called aquatint was developed which allowed artists to develop a range of tones that weren't just built up by cross hatched lines.It follows the idea that grey tones in printing can be achieved through very small dots. An acid resistant powder like rosin can be used to do this (see fig. 1).
After the rosin powder is melted onto the plate, the plate is put into the acid bath (see fig. 2 and 3).
Because the rosin resists the acid, the plate is etched around the rosin resulting in a tone (see fig. 3).
The darkness of the tone can be controled by the time in the acid and by how much rosin in on the plate.

Zinc plates are often used for etching. They are etched with a relatively weak nitric acid/water solution often in the range between 6:1 to 15:1. The faster the plate etches, the rougher-ragged the etched marks will be. Zinc plates have the advantage of being softer than copper or steel. This makes them easier to use if you are scraping and burnishing the plate. However, for finer lines, engraving, or stablity over long print runs, the softness is a disadvantage.
Nitric acid will etch a zinc plate outwards once it gets below the surface. This makes it easier to "foul-bite" or "false-bite" a plate; this is also called "crevŽ". (see figure 3) Copper, another common etching plate material, is much harder than zinc. It is etched using a Ferric Chloride solution, Dutch Mordant (water, hydrochloric acid and potassium chlorate), or a very powerful nitric acid (1:2). Ferric chloride and dutch mordant etch very sharp lines and fine aquatints.
Ferric chloride is often etched upside down to allow sediment to fall out of the areas that are etching. Copper etches "cleanly" because the acids tend to bite straight down into the plate rather than spreading outwards like in zinc etching. Because of its hardness, it is more suitable for drypoint and engraving. As with zinc, the hardness may be to your advantage or disadvantage. For added stability, copper is also sometimes steelfaced. This involves coating the entire plate with a microscopicly thin layer of steel.
Bronze plates are yet another option. I used this type of plate material at the "Taller del Alquimista" in Valparaiso, Chile. We used bronze because even though Chile is one of the worlds major copper producers, it is hard to get a high grade copper that would be good for intaglio. Bronze is harder than copper and allowed us to get very fine detail in the images.
Steel is even harder. It is etched using nitric acid and allows extremely high amounts of detail for engaving. Steel plates are used for the plates from which money is printed. Image:Close up of zinc and copper plates

Photogravure is a complex etching process that involves working with photographic images. Photogravure follows the concept that in order to print a photograph with black ink, a dot pattern must be created in order to show varying degrees of gray tones using the white of the paper. This concept is still used in the printing industry and is called a half tone and can easily seen in the photographs in a newspaper. Dots of varying sizes make up the tones we see in the photograph.
Since photographic negatives start off as a continuous tone, the image must be converted in order to print it with ink. The dot pattern in a photogravure is the dot pattern created by a rosin aquatint on a highly polished copper plate. This creates a beautiful, very subtle quality to the photograph. The pattern is actually the random pattern of the dust settling on the plate.A photosensitive gelatin is put on the plate after the aquatint. Then, a negative is exposed onto the gel.
The plate is placed in a Ferric Chloride acid bath and the image is etched into the plate.The printing process is different from other types of intaglio, notably the wiping and inking. The printing pressure is also much higher. Because of this, it is good to steel face the plate in order to preserve the image.Summary of the process with some images from the studios of John Goodman Photogravure.