Modern Technique

A waxy acid-resist, known as a ground, is applied to a metal plate, most often copper or zinc but steel plate is another medium with different qualities. There are two common types of ground, hard ground and soft ground. Hard ground can be applied in two ways. Solid hard ground comes in a hard waxy block. To apply hard ground of this variety the plate to be etched is placed upon a hot-plate, a kind of metal worktop that is heated up. The plate heats up and the ground is applied by hand, melting onto the plate as it is applied. The ground is spread over the plate as evenly as possible using a tool called a Dabber. A dabber is often a short wooden handle with a large round wadding at the end covered in leather. The ground is spread over the plate using a rocking motion with the dabber. Once applied the etching plate is removed from the hot-plate and allowed to cool which hardens the ground. The second way to apply hard ground is by liquid hard ground. This comes in a can and is applied with a brush upon the plate to be etched. Exposed to air the hard ground will harden. Some printmakers use bitumen as hard ground, although often bitumen is used to protect steel plates from rust and copper plates from aging. After the ground has dried the artist uses a sharp tool to scratch into the ground, exposing the metal. Soft ground also comes in liquid form and is allowed to dry but it does not dry hard like hard ground and is impressionable. After the soft ground has dried the printmaker may apply materials such as leaves, objects, hand prints and so on which will penetrate the soft ground and expose the plate underneath. The ground can also be applied in a fine mist, using powdered rosin or spraypaint. This process is called aquatint, and allows for the creation of tones, shadows, and solid areas of color. The plate is then completely submerged in an acid that eats away at the exposed metal. Copper plates and zinc plates are often dipped into ferric chloride solution and steel plates are dipped into nitric acid. Solutions are usually 2 parts FeCl3 to 2 parts water or for steel plate, 1 part nitric to 3 parts water. The strength of the acid determines the speed of the etching process. The etching process is known as biting (see also spit-biting below). The waxy resist protects the acid from biting the parts of the plate have not been exposed. The longer the plate remains in the acid the deeper the "bites" become. Examples of etching techniques etching aquatint soft ground etching (vernis-mou) During the etching process the printmaker uses a bird feather or similar item to wave away bubbles and detritus, produced by the dissolving process, from the surface of the plate. If a bubble is allowed to remain upon the plate then it will stop the acid biting into the plate where the bubble resides. Zinc produces more bubbles much more rapidly than copper and steel and some artists use zinc's ability to do this to produce interesting round bubble like circles within their prints like a milky way effect. The detritus is powdery dissolved metal that fills the etched grooves and can also block the acid from biting evenly into the exposed plate surfaces. Another way to remove detritus from a plate is to place the plate to be etched face down within the acid upon plasticine balls or marbles, although the drawback of this technique is the exposure to bubbles and the inability to remove them readily. For aquatinting a printmaker will often cut off a test strip of metal about a centimetre to three centimetres wide. The strip will be dipped into the acid for a specific number of minutes or seconds. The metal strip will then be removed and the acid washed off with water. Part of the strip will be covered in ground and then the strip is redipped into the acid and the process repeated. The ground will then be removed from the strip and the strip inked up and printed. This will show the printmaker the different degrees or depths of the etch, and therefore the strength of the ink color, based upon how long the plate is left in the acid. The plate is removed from the acid and washed over with water to remove the acid. The ground is removed with a solvent such as turpentine. Turpentine is often removed from the plate using methylated spirits as turpentine is greasy and can affect the application of ink and the printing of the plate. The entire plate is inked. Spit-biting is a process whereby the printmaker will apply acid to a plate with a brush in certain areas of the plate. The plate may be aquatinted for this purpose or exposed directly to the acid. A piece of matte board, a plastic "card", or a wad of cloth is often used to push the ink into the incised lines. The surface is wiped clean with a piece of stiff fabric known as tarlatan and then either wiped with newsprint paper or some printmakers prefer to use the blade part of their hand or palm at the base of their thumb. The wiping leaves ink in the incisions. You may also use a folded piece of organza silk to do the final wipe. If copper or zinc plates are used plate surface is left very clean and therefore white in the print. If steel plate is used then the plate's natural tooth gives the print a grey background similar to the effects of aquatinting. As a result steel plates do not need aquatinting as gradual exposure of the plate via successive dips into acid will produce the same result. A damp piece of paper is placed over the plate and it is run through the press.