Press and Diagram

Dry Processes

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!

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Wet Processes

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.

Line Etching and Aquatints

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.

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Plates and Materials

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

Close up of a photogravure print

Steel faced photogravure plate

Wiping the plate

Wiping the plate

Printing

Print and the plate on the press bed

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.

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Lithography was invented by a man named Alois Senefelder in the 1790's. Since then, it has been used as an artist medium but it has also been the basis which developed into the industrial, high speed production printing that is done today. Its relationship to industrial processes is important for artists to note for conceptual and technical reasons. Lithographic prints are characterized by the their flatness, and the wide variety of tones and marks that can be achieved, especially by a good printer.

I am going to discuss lithography in terms of the older techniques and its use as an artists medium.

1. The first thing that needs mentioning is the main chemical principle of lithography, which is that water and oil do not mix. In our case, oil is the base of the ink and drawing mediums we use. The printing matrix from which we use could be an aluminum plate or, my favorite, a perfectly flat piece of limestone.

2.An image is chemically bonded to the stone using an "etch". The basic etch is nitric acid suspended in vehicle of gum arabic. The strength of the etch depends on how greasy the drawing materials are. The greasier the image the stronger the etch will need to be. The etch is buffed into the stone using soft cheesecloth and allowed to dry and harden.(see etching the stone for a more detailed description)

3.A thin film of water is applied to the stone or plate using a sponge.

4.The image is inked with a roller. For black ink, a wooden roller covered in leather is often used. The water film repels the oil based ink from the non image areas, and a layer of ink is built up within the image area.

5.The paper is placed on the inked image. A tympan sheet, which is usually an acrylic or lexan sheet, is placed on top of that. The scraper bar is lowered onto the tympan. The press is designed to put a great deal of pressure on the stone or plate with the scraper bar. The press then moves the stone or plate by either a hand crank or motor. The scraper bar scrapes across the tympan exerting even pressure across the inked image. The ink is thus transferred onto the paper.(see also fig.6 for a diagram on how the basic lithographic press works.)

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When someone talks about 'relief printing' they are usually referring to letterpress, woodcuts, wood engravings, or linoleum cuts. Relief printing encompasses a broad range of techniques and possibilities for artists and designers. This is especially true for the book artist because of its history in the production of books. Relief printing allows for extremely clean, sharp lines and beautiful tactile readable texts while woodcuts have many expressive mark-making possibilities.

1. Relief printing involves a print matrix which has a raised surface. The raised surface is what prints. In woodcuts, linoleum cuts, and wood engravings the recessed areas are physically removed with carving tools. Others, like lead type, which is cast from matrices specially designed for the purpose, are machine made. Today, casting type from lead is done on a limited scale but was once the industry standard for printing most text. It has also become common to photographically produce relief plates with text or images on magnesium and photo polymer plates.

2. Ink is applied to the raised surface area using a special press with automatic inking rollers, or a hand roller (brayer). As the roller passes over the surface it only reaches the image area (raised area). This can be controlled and optimized with varying softness of rollers.

3. A thin layer of ink is now on the image area.

4. The block is put into a special press. There are many different kinds of presses. Some presses ink the type or blocks while they are on the press. Pressure is put on the back of the paper either by a cylinder or in a direct manner as in the case of a platen press. Sometimes woodcuts are printed on an etching press. This is often discouraged by etchers but can produce good results. Woodcuts can also be "hand rubbed". This process involves placing the paper and rubbing the back with what looks like a wooden Japanese rice spoon or a special tool called a baren. Hand rubbing is more time consuming and laborious but offers extremely subtle and beautiful effects for those who master it.

5. A relief print is most easily recognized by what is called "impression". This refers to the indention caused by the relief pressing into the paper. It is often so subtle that it can barely be felt with ones fingertips. Controlling the impression is an important concern for letterpress printers

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Cutting Possibilities of Relief

The first thing the artist making a relief print must decide is what material to use.

1. There are a number of different woods and other man-made materials one can cut to make a relief print. These matrices begin with a halved potato and end with polymer resin wood engraving substitutes.

2. A potato print or rubber stamp are technically a basic form of relief printing. They are easy to ink (stamp pad), easy to register (by eye), and fast to use. The results rarely fall into the classification of "fine printing", but can be used to create very interesting effects because of the speed which one can work.

3. Linoleum comes in various forms. There is a soft printing linoleum which is sometimes called 'battleship linoleum' this is definately the best for printing. It comes in a roll, about 1/8 inch thick, or mounted on a block of particle board; close to type high. Linoleum is easy to cut and can be further softened with heat. When compared to wood, linoleum does have a tendency to dull tools pretty quickly and it lacks the lively qualities of wood like the grain and the its natural inconsistencies. However, the advantage is the fact that the problems that arise from cutting across the wood grain are eliminated.

4. There are many options in terms of wood. Traditionally, fruit woods and box woods are used. These woods are extrmemly hard and are a nice option for the person who wants detail and enjoys quality materials. This can be expensive and printing from a board can be difficult if it warps.

5. Plywood comes with a variety of veneers, of what birch is quite popular. Other people enjoy more textured plywoods like luan. Plywood doesn't seem to warp as readily as plank wood, but has the problem of having an occasional knot hole under the veneer that can result in areas of the block unexpectedly becoming useless.

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