Etching is a printmaking process in which lines or areas are cut using acid into a metal plate in order to hold the ink. In etching, the plate can be made of iron, copper, or zinc.
To prepare the plate for etching, it is first polished to remove all scratches and any marks from the surface. When the surface is completely smooth and clean, it is covered evenly with a thin coat of acid-resistant varnish or wax, which is called the ground.
Using a tool called an etching needle, the printmaker gently scratches away parts of the varnish or wax following the design, thereby exposing the metal beneath.
Once the entire design has been drawn into the ground, acid is poured over the plate or dipped in acid.
The acid eats into the metal only in the exposed areas creating recesses that can retain ink.
The depth and width of these recesses are determined by the length of time the plate is exposed to the acid: a longer exposure will cause deeper and wider recesses, which hold more ink and will thus print darker lines on paper.
This process can be used to create a subtle tonal effect. To create darker tones, certain areas can be bathed in acid several times, while lighter areas are protected from further acid bite by covering them with varnish or wax.
Once the plate has been satisfactorily bitten by the acid, the printmaker removes the ground with a solvent
After the varnish or wax is removed, the plate is ready for inking. In this process, the ink is retained in the cut lines.
A cloth ball, or equivalent material is used to gently spread ink across the whole face of the plate; the same material is used to remove most of the excess ink from the surface.
The plate is further cleaned using cheesecloth or other heavily starched material.
Sometimes, printmakers often use the sides of their hands to wipe away the last bits of ink. In certain cases, a printmaker can choose not to clean the plate entirely, but to leave a thin coat of ink on the plate to create tone.
Once the surface of the plate is wiped clean to a satisfactory level, the plate is placed on the bed of a rolling printing press, with the ink side up.
Although some early etched prints appear to have been produced by simply pressing the paper against the plate with one’s hands, in most cases the pressure required to force the paper into the finely cut lines entailed the use of a special press equipped with rollers.
Before the plate is moved through the press, it is covered with a sheet of dampened paper and then printing blankets, often made of felt, to soften the pressure on the metal plate.
Once printed onto its paper support, the etching’s design appears in reverse of the original on the plate. The pressure of the press not only forces the ink onto the damp paper but also produces an outline of the outer edges of the metal plate in the paper, known as a plate mark.
The making of etching is a very skilled and time-consuming process and the artist has to take into account that the finished work will appear in reverse of the finished etching.
Like etching, aquatint is a similar printmaking technique, but is used to create tonal effects rather than lines.
In Aquatint, fine particles of acid-resistant material, such as powdered rosin, which is a solid form of resin, are attached to a printing plate by heating.
The plate is then immersed in an acid bath, just like an etching. The acid eats into the metal around the particles to produce a granular pattern of tiny indented rings
These hold sufficient ink to give the effect of an area of wash when inked and printed. The extent of the printed areas can be controlled by varnishing those parts of the plate to appear white in the final design.
Gradations of tone can be achieved by varying the length of time in the acid bath; longer periods produce more deeply-bitten rings, which print darker areas of tone.
The technique was developed in France in the 1760s and became popular in Britain in the late eighteenth and early nineteenth centuries.
All the Dirty Dogs of Paris etchings by Boris O’Klein on this site are hand coloured in watercolour.