Plastic sprays are also used to make aquatints. These lacquers and enamels are sold in pressurized spray cans and are sufficiently acid resistant to use for moderately long bites. They are easy to control and simpler to use, but they must be used in spray booths or other wellventilated places. Lift-ground etching (sugar-lift aquatint)
In lift-ground etching, a positive image is etched on an aquatint plate by drawing with a water-soluble ground. In the conventional aquatint technique, the artist controls the image by stopping out negative areas with varnish, thus working around the positive image. But for lift-ground etching, he uses a viscous liquid (such as India ink, gamboge, or ordinary poster paint mixed with sugar syrup) to paint directly on the plate. After the painting is finished and dried, the whole surface is covered with thin, liquid hard ground. When dry, the plate is placed in lukewarm water that dissolves the painted design, lifting the ground and dislodging it from the places that had been painted, thus exposing the metal surface to be etched. Aquatinting can be handled two ways: either the whole plate can be aquatinted before painting with lift ground or it can be aquatinted after the design is lifted. Lift-ground etching is particularly well-suited to free, spontaneous, calligraphic designs. Acids and the etching process
The acid bite of the plate is a critical stage in the making of an etching. The printmaker must be familiar with the characteristics of the materials that are being used. On a zinc plate nitric acid is used. In the process of biting, this acid develops air bubbles over the bitten area. Under the bubbles the acid action is slower, and, therefore, if the bubbles are not constantly moved around by brushing, the etched line will be uneven. Nitric acid also has a tendency to underbite, that is, to bite not only straight down but also sideways. For this reason, areas of dense texture must be watched very closely.
Nitric acid also can be used on copper, but, except to bite out large areas, Dutch mordant is much better suited for this metal. The action of hydrochloric acid on copper is much more even and controlled than that of nitric acid. Thus, for a bold, rough bite, nitric acid on zinc is fine; but for delicate, controlled etching, Dutch mordant on copper is preferred. Metal graphic
This method was originated by Rolf Nesch, the German-Norwegian printmaker. In all the intaglio methods previously discussed, the artist’s design was created by making incisions in the plate. Nesch’s method is the reverse of this process: the design is built up like a montage, by cutting out metal shapes and soldering them on the plate surface. Instead of the etching needle and the graver, the tools are shears, wire cutters, and a soldering iron. These plates are in deep relief and thus produce a heavily embossed print. Often such plates are combined with conventionally etched or engraved sections. In addition to metal shapes, wood and plastics may be used. Because of the extremely high relief, the printing of the plates requires specially prepared presses. A few contemporary artists work in such a high relief that the ordinary etching press cannot print their work and standard printing papers cannot be used. In some cases the high relief is created by compressing paper pulp into molds with hydraulic presses.
The use of embossing is not new. Some Japanese woodcuts have sections that have been decorated with “goufrage” (blind pressing). In contemporary printmaking, embossing has become a major interest, and many artists are exploring the possibilities of the intaglio print by using shallow paper bas-reliefs to exploit the interplay of shadow and light. Printing by intaglio processes
The most important piece of equipment in intaglio printing is the etching press, a simple machine whose basic principle has not changed for centuries. Motorization and the use of pressure gauges are the only major improvements. The press consists of a solid steel plate, called the bed, that is driven between two rollers; a screw mechanism on both sides of the top roller adjusts the pressure. Large modern presses are motor driven.
The print is made by placing the inked plate face up on the bed. Dampened paper is placed carefully on the plate and covered with several layers of pure wool printing felts. The bed is then driven through the rollers. The felts, which are squeezed between the metal rollers and the plate, push the paper into the crevices of the plate, forcing the paper into contact with the ink and thus transferring the image.
A fairly heavy pure rag paper is normally used. It is soaked until its fibres are softened and then, before printing, it is blotted until no surface water is visible. For inking, the plate is placed on a heater and kept warm throughout the inking and wiping steps. Heat makes the ink looser and thus facilitates both of these processes. Wiping is the operation in which the ink is removed from the surface of the plate, while leaving it in the recesses. Usually a carefully folded starched cheesecloth (tarlatan) is used. When a clean, crisp print is desired, the plate is given a final wiping with the palm of the hand.
Inks for intaglio printing are especially made for this purpose. The consistency of the ink must be such that it comes off the surface of the plate cleanly during the wiping operation, but at the same time it must have enough body to retain its relief on the paper. The printing ink must also have sufficient viscosity to stick to the damp printing paper to produce a clear and rich image.
After the print is pulled, it is dried, either between blotters or taped to a large, stiff board. This choice depends on the size of the print and the type of paper used. Intaglio colour printing
The intaglio colour print is made with two or more intaglio plates successively overprinted on the same paper. Each plate represents one colour and its possible gradations. In principle, it is possible to take four plates—the three basic colours, yellow, red, and blue, plus black—and make a print that will have the full range of colours. If the colour areas are distinctly separated, more than one colour can be printed from one plate. This method involves an extremely meticulous inking and wiping process.
One of the greatest problems with intaglio colour printing is registering the successive colours in their precise location. If the colours can be printed immediately, wet on wet, then it is relatively simple, but often this is not possible. If the first plate has high relief and is overprinted while wet, the second plate will crush it completely. In this case the first print must be thoroughly dried and then rewetted for the second printing. Because the paper shrinks in the drying process, it is difficult to get it back to the original size when rewetted.
Several methods of registering can be used, depending on the particular problem. For wet-on-wet printing the process is simple. After both plates are inked, the first plate is placed on the press bed and its position is marked. Paper is placed over the plate and secured at one end with masking tape, or, if there is enough margin, the paper is run through so that one end remains caught under the printing roller. The print is then folded back and the first plate is replaced with the second.
Another method uses mats. The paper to be used in the edition is cut to the same size. A cardboard or metal mat is cut, corresponding to the size of the wet paper. The plate position is either cut out or marked on the mat. Registration consists of lining the paper up with the mat.
The most precise registering is with pinholes. Two pinholes are punched in opposite corners of the mat. Corresponding pinholes are punched through all the printing papers. In printing, the paper is picked up with two heavy needles through the punched holes. The needles are then inserted in the corresponding holes on the mat and the paper is released. The holes should be placed close to an edge that will be trimmed after the print is dry. Stencilled colours with an intaglio plate